DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application on 08 January 2026 after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 31 December 2025 has been entered.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-9 and 11-15 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Regarding claims 1-5 and 12-13, the term “substantially” is a relative term which renders the claim indefinite. The term “substantially” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. As far as the phrase “substantially square” in combination with requiring the profile to be “in the form of a super-ellipse”, this is not sufficient to provide a standard for determining the requisite degree of “square”-ness that is meant to be covered by the term “substantially square”. Super-ellipses are defined by mathematical equations and can range from a shape that looks, to the naked eye, to be a square (with n ≥ 100 and side lengths being equal), a rectangles (n ≥ 100, one side length >> other side length), circles (n=2, side lengths equal), ellipses (n=2, side lengths ≠ ), stars/astroids (0 < n < 1). Thus, defining the profile as super-ellipse is not sufficient to provide a standard for ascertaining the requisite degree of “substantially”. The Specification does not provide sufficient clarification for the term. Although p,22 provides a sample equation for the super ellipses considered by Applicant, the range of n values includes 2, which is, to the naked eye, a circle. It does not seem reasonable to consider a circle to be substantially square. Thus the Specification does not shed light on what the requisite degree is for “substantially square”.
Dependent claims 2-9 and 13-15 are also rejected for depending on at least on rejected claim above.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 6, and 12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Powell 9777631 in view of Suciu 20170122207 and Rahimi (A.B. Rahimi, Comparison of Lift and Drag Forces for Some Conical Bodies in Supersonic Flow Using Perturbation Techniques, July 2012, International Journal of Engineering Transactions A” Basics Vol.25, No.3, 231-238).
Regarding Claim 1, Powell teaches a turbofan gas turbine engine (10) comprising,
an outer housing (48); and
in axial flow sequence, a fan assembly (14), a compressor module (16), a turbine module (20, 22), and an exhaust module (58, 60),
wherein the fan assembly, the compressor module, the turbine module, and the exhaust module are within the outer housing (Figs 1-5),
wherein the fan assembly comprises a plurality of fan blades (34, 38, 44) defining a fan diameter (D; defined by 34, 38, or 44),
an inlet duct (49 of 48) in fluid communication with the fan assembly (Figs 1-5) and having a substantially square radial cross-sectional profile (Figs 2, 5; with equal side lengths like a square and rounded corners), the substantially square radial cross-sectional profile being an overall shape of the inlet duct within the outer housing (Figs 2, 5),
wherein an airflow passes into the inlet duct prior to flowing to the fan assembly (Figs 1-5).
Powell does not teach a heat exchanger module in fluid communication with the fan assembly via the inlet duct; the heat exchanger module configured to cool the engine and being within the outer housing; the heat exchanger module comprising a plurality of radially-extending hollow vanes arranged in an equi-spaced circumferential array with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially extending hollow vanes; and the heat exchanger module having the substantially square radial cross-sectional profile further defined to be in the form of a super-ellipse, the substantially square radial cross-sectional profile being an overall shape of the heat exchanger within the outer housing, wherein the hollow vanes each include a hollow portion through which a portion of the airflow passes prior to flowing to the fan assembly, and at least one of the hollow vanes accommodates at least one heat transfer element in the hollow portion for the transfer of heat from a first fluid contained within the at least one heat transfer element to the portion of the airflow passing through the hollow vane and over a surface of the at least one heat transfer element, the portion of the airflow enters the hollow portion before passing over the surface of the at least one heat transfer element, and the circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes.
However, Suciu teaches a turbofan gas turbine engine (10, Fig 1) comprising,
an outer housing (Fig 1 below); and
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in axial flow sequence, a heat exchanger module (82, Fig 2), a fan assembly (12), a compressor module (14), a turbine module (18), and an exhaust module (22),
wherein the heat exchanger module, the fan assembly, the compressor module, the turbine module, and the exhaust module are within the outer housing (Fig 1),
the fan assembly comprises a plurality of fan blades (downstream of vanes in Figs 1-2; as required for axial flow fan) defining a fan diameter (from tip to tip and intersecting the central axis, Fig 1),
the heat exchanger module is in fluid communication with the fan assembly by an inlet duct (axial extent between vanes of Fig 2, and fan stage in Fig 1),
the heat exchanger module configured to cool the engine (heat exchange module being wholly contained in the engine, at least one of the fluids/structures of/in the heat exchange module being cooled) and comprising a plurality of radially-extending hollow vanes (82) arranged in an equispaced circumferential array (Figs 1-2) with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially-extending hollow vanes (for 106 in Figs 2-4), and
the heat exchanger module has a radial cross-sectional profile conforming to the shape of the outer housing (Figs 1-4), the radial cross-sectional profile being an overall shape of the heat exchanger module within the outer housing (Figs 1-4),
wherein the hollow vanes each include a hollow portion (incl. 101, 102, 104) through which a portion of an airflow passes (airflow entering outer housing passes into 101 and between vanes 82) prior to flowing to the fan assembly (Figs 1-4),
one of the hollow vanes accommodates at least one heat transfer element (incl.88) in the hollow portion for transferring heat from a first fluid (oil; col.2 ll.58-end) contained within the at least one heat transfer element to the portion of the airflow passing through the hollow vane and over a surface of the at least one heat transfer element (Figs 2-4), the portion of the airflow enters the hollow portion (at 101) before passing over the surface of the at least one heat transfer element (via 102, 104), and
a circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes (Fig 4 depicts a single vane with circumferential span that is smaller than the adjacent radially inner platform extent, thus teaching the circumferential space between adjacent vanes being greater than the circumferential span of a single vane; see also 112b interpretation above).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Powell to include the heat exchanger module of Suciu, in order to provide desirable oil cooling using air that will contribute to the thrust by joining the bypass flow, in a manner that does not reduce efficiency (Suciu, col.1 ll.26-34, col.3 ll.20-34). Note, the resulting engine of Powell in view of Suciu is characterized by the heat exchanger module having an overall shape that is a square radial cross-sectional profile.
Powell in view of Suciu still does not teach whether the substantially square cross-sectional profile of Powell (apparently square with rounded corners) is in the form of a super-ellipse or not.
However, radiused (or rounded-corner) squares are widely recognized as substitutional equivalents to super elliptical square (or squircle) shapes, differing mainly in design preference (as evidenced by any google search for comparing a squircle and a rounded square). Depending on the specific values of the variables in a super ellipse equation, the resulting squircle may be indistinguishable to the naked eye from a circle, square, or rounded square. Even in technical fluid flow applications, the terms “squircle” (by definition, a super ellipse) and “square with rounded corners” are used interchangeably (Rahimi, Abstract).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the rounded-square profile of Powell (in view of Suciu) to be a super ellipse, because Rahimi teaches the two are considered substitutional equivalents (Rahimi, Abstract).
Regarding claim 6, Powell in view of Suciu and Rahimi teaches all the limitations of the claimed invention as discussed above. Powell in view of Suciu and Rahimi as discussed so far, does not teach the at least one heat transfer element extends axially within a corresponding one of the hollow vanes.
However, Suciu further teaches the at least one heat transfer element (incl.88) extends axially within a corresponding one of the hollow vanes (each of 88, and the combination of all the 88 comprises an axial extent within the corresponding hollow vane; Figs 2, 4).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the engine of Powell in view of Suciu and Rahimi to include the heat transfer element of Suciu, in order to provide desirable oil cooling using air that will contribute to the thrust by joining the bypass flow, in a manner that does not reduce efficiency (Suciu, col.1 ll.26-34, col.3 ll.20-34).
Regarding claim 12, Powell teaches a method of operating a turbofan gas turbine engine (10), the gas turbine engine comprising,
an outer housing (48); and
in axial flow sequence an inlet duct (49 of 48), a fan assembly (14), a compressor module (16), and a turbine module (20, 22), and an exhaust module (58, 60),
the fan assembly comprising a plurality of fan blades (34, 38, 44) defining a fan diameter (D; defined by 34, 38, or 44),
the method comprising:
(i) providing the fan assembly, the compressor module, and the turbine module, and the exhaust module within the outer housing (Figs 1-5);
(ii) providing the inlet with a substantially square radial cross-sectional profile that is an overall shape of the inlet (Figs 2, 5), where a side length of the substantially square cross-section is D (Figs 2, 5); and
(iii) positioning the inlet in fluid communication with the fan assembly (Fig 1) such that an airflow passes into the inlet prior to flowing to the fan assembly (Figs 1-5).
Powell does not teach a heat exchanger module upstream of, and in fluid communication with, the fan assembly via the inlet duct; the heat exchanger module within the outer housing; the heat exchanger module configured to cool the engine and having the substantially square radial cross-sectional profile as an overall shape, the substantially square radial cross-sectional profile being in the form of a super-ellipse; (iv) providing the heat exchanger module with a plurality of radially-extending hollow vanes arranged in an equispaced circumferential array with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially-extending hollow vanes, the hollow vanes each include a hollow portion through which a portion of the airflow passes, at least one of the hollow vanes accommodating at least one heat transfer element in the hollow portion for transfer of heat energy from a first fluid contained within the at least one heat transfer element to a the portion of the airflow passing through the hollow vane and over a surface of the at least one heat transfer element, and a circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes; and (v) operating the gas turbine engine such that the portion of the airflow enters the hollow portion before passing over the surface of the at least one heat transfer element.
However, Suciu teaches a turbofan gas turbine engine (10, Fig 1) comprising,
an outer housing (Fig 1 below); and
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in axial flow sequence, a heat exchanger module (82, Fig 2), a fan assembly (12), a compressor module (14), a turbine module (18), and an exhaust module (22),
wherein the heat exchanger module, the fan assembly, the compressor module, the turbine module, and the exhaust module are within the outer housing (Fig 1),
the fan assembly comprises a plurality of fan blades (downstream of vanes in Figs 1-2; as required for axial flow fan) defining a fan diameter (from tip to tip and intersecting the central axis, Fig 1);
the heat exchanger module is in fluid communication with the fan assembly by an inlet duct (axial extent between vanes of Fig 2, and fan stage in Fig 1),
the heat exchanger module configured to cool the engine (heat exchange module being wholly contained in the engine, at least one of the fluids/structures of/in the heat exchange module being cooled) and comprising a plurality of radially-extending hollow vanes (82) arranged in an equispaced circumferential array (Figs 1-2) with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially-extending hollow vanes (for 106 in Figs 2-4), and
the heat exchanger module has a radial cross-sectional profile conforming to the shape of the outer housing (Figs 1-4), the radial cross-sectional profile being an overall shape of the heat exchanger module within the outer housing (Figs 1-4),
wherein the hollow vanes each include a hollow portion (incl. 101, 102, 104) through which a portion of an airflow passes (airflow entering outer housing passes into 101 and between vanes 82) prior to flowing to the fan assembly (Figs 1-4),
one of the hollow vanes accommodates at least one heat transfer element (incl.88) in the hollow portion for transferring heat from a first fluid (oil; col.2 ll.58-end) contained within the at least one heat transfer element to the portion of the airflow passing through the hollow vane and over a surface of the at least one heat transfer element (Figs 2-4), the portion of the airflow enters the hollow portion (at 101) before passing over the surface of the at least one heat transfer element (via 102, 104), and
a circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes (Fig 4 depicts a single vane with circumferential span that is smaller than the adjacent radially inner platform extent, thus teaching the circumferential space between adjacent vanes being greater than the circumferential span of a single vane; see also 112b interpretation above).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Powell to include the heat exchanger module of Suciu, in order to provide desirable oil cooling using air that will contribute to the thrust by joining the bypass flow, in a manner that does not reduce efficiency (Suciu, col.1 ll.26-34, col.3 ll.20-34). Note, the resulting engine of Powell in view of Suciu is characterized by the heat exchanger module having an overall shape that is a square radial cross-sectional profile.
Powell in view of Suciu still does not teach whether the substantially square cross-sectional profile of Powell (apparently square with rounded corners) is in the form of a super-ellipse or not.
However, radiused (or rounded-corner) squares are widely recognized as substitutional equivalents to super elliptical square (or squircle) shapes, differing mainly in design preference (as evidenced by any google search for comparing a squircle and a rounded square). Depending on the specific values of the variables in a super ellipse equation, the resulting squircle may be indistinguishable to the naked eye from a circle, square, or rounded square. Even in technical fluid flow applications, the terms “squircle” (by definition, a super ellipse) and “square with rounded corners” are used interchangeably (Rahimi, Abstract).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the rounded-square profile of Powell (in view of Suciu) to be a super ellipse, because Rahimi teaches the two are considered substitutional equivalents (Rahimi, Abstract).
Claims 1, 6, and 12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Powell 9777631 in view of Marchaj 20210270148 and Rahimi.
Regarding Claim 1, Powell teaches a turbofan gas turbine engine (10) comprising,
an outer housing (48); and
in axial flow sequence, a fan assembly (14), a compressor module (16), a turbine module (20, 22), and an exhaust module (58, 60),
wherein the fan assembly, the compressor module, the turbine module, and the exhaust module are within the outer housing (Figs 1-5),
wherein the fan assembly comprises a plurality of fan blades (34, 38, 44) defining a fan diameter (D; defined by 34, 38, or 44),
an inlet duct (49 of 48) in fluid communication with the fan assembly (Figs 1-5) and having a substantially square radial cross-sectional profile (Figs 2, 5; with equal side lengths like a square and rounded corners), the substantially square radial cross-sectional profile being an overall shape of the inlet duct within the outer housing (Figs 2, 5),
wherein an airflow passes into the inlet duct prior to flowing to the fan assembly (Figs 1-5).
Powell does not teach a heat exchanger module in fluid communication with the fan assembly via the inlet duct; the heat exchanger module configured to cool the engine and being within the outer housing; the heat exchanger module comprising a plurality of radially-extending hollow vanes arranged in an equi-spaced circumferential array with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially extending hollow vanes; and the heat exchanger module having the substantially square radial cross-sectional profile further defined to be in the form of a super-ellipse, the substantially square radial cross-sectional profile being an overall shape of the heat exchanger within the outer housing, wherein the hollow vanes each include a hollow portion through which a portion of the airflow passes prior to flowing to the fan assembly, and at least one of the hollow vanes accommodates at least one heat transfer element in the hollow portion for the transfer of heat from a first fluid contained within the at least one heat transfer element to the portion of the airflow passing through the hollow vane and over a surface of the at least one heat transfer element, the portion of the airflow enters the hollow portion before passing over the surface of the at least one heat transfer element, and the circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes.
However, Marchaj teaches a turbofan gas turbine engine (Fig 1) comprising,
an outer housing (62); and
in axial flow sequence, a heat exchanger module (incl. 110), a fan assembly (incl.42), a compressor module (incl. 44, 52), a turbine module (54, 46), and an exhaust module (aft of turbine; [0038]),
wherein the heat exchanger module, the fan assembly, the compressor module, and the turbine module are within the outer housing (Fig 1),
the fan assembly comprises a plurality of fan blades (42) defining a fan diameter (D, from tip to tip, intersecting centerline X),
the heat exchanger module is in fluid communication with the fan assembly by an inlet duct (defined by portion of 15, 62 from 110 to 42),
the heat exchanger module is configured to cool the engine (heat exchange module being wholly contained in the engine, at least one of the fluids/structures of/in the heat exchange module being cooled) and has a radial cross-sectional profile conforming to the shape of the outer housing (Figs 1, 4), the radial cross-sectional profile being an overall shape of the heat exchanger module within the outer housing (Figs 1, 4),
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the heat exchanger module comprises a plurality of radially-extending hollow vanes (a set of three struts 110 considered to read on a hollow vane per Fig 4 above; Figs 1, 5-6) arranged in circumferential array (Figs 1, 3-6) with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially-extending hollow vanes (Fig 4 above), and
wherein the hollow vanes each include a hollow portion (between every other strut per Fig 4 below) through which a portion of an airflow passes prior to flowing to the fan assembly (Figs 1, 5),
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at least one of the hollow vanes accommodates at least one heat transfer element (at least portion 115 of the central strut of each set of struts further comprising at least 120, 109) in the hollow portion for the transfer of heat from a first fluid (114) contained within the at least one heat transfer element to the portion of the airflow passing through the hollow vane and over a surface (suction and pressure sides of central strut 100 of the set of struts) of the at least one heat transfer element (Figs 1, 4-6),
the portion of the airflow enters the hollow portion before passing over the surface of the at least one heat transfer element (air enters past leading edges 122 of every other strut, before passing over portion 115 of the central strut of each set of three struts forming the hollow vane), and
a circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes (interpreted under 112b discussion above as referring to any dimension of the space and any circumferential span of the hollow vanes; looking to Fig 4, the circumferential span of each hollow vane at some point toward the radially inner end of the vane is smaller than the largest radial and circumferential dimensions of the space between the hollow vanes).
Although Fig 4 of Marchaj depicts 11 struts, paragraph [0048] teaches more, or fewer may be utilized, and using just one more strut or two fewer struts provides equispacing to the circumferential array. Furthermore, MPEP 2144.05(I) provides that a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close.
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the engine of Powell to include the heat exchanger module of Marchaj, in order to mitigate ice accumulation at the engine inlet which can adversely impact engine operation (Marchaj, [0003]). Note, the resulting engine of Powell in view of Marchaj is characterized by the heat exchanger module having an overall shape that is a square radial cross-sectional profile.
Powell in view of Marchaj still does not teach whether the substantially square cross-sectional profile of Powell (apparently square with rounded corners) is in the form of a super-ellipse or not.
However, radiused (or rounded-corner) squares are widely recognized as substitutional equivalents to super elliptical square (or squircle) shapes, differing mainly in design preference (as evidenced by any google search for comparing a squircle and a rounded square). Depending on the specific values of the variables in a super ellipse equation, the resulting squircle may be indistinguishable to the naked eye from a circle, square, or rounded square. Even in technical fluid flow applications, the terms “squircle” (by definition, a super ellipse) and “square with rounded corners” are used interchangeably (Rahimi, Abstract).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the rounded-square profile of Powell (in view of Marchaj) to be a super ellipse, because Rahimi teaches the two are considered substitutional equivalents (Rahimi, Abstract).
Regarding claim 6, Powell in view of Marchaj and Rahimi teaches all the limitations of the claimed invention as discussed above. Powell in view of Marchaj and Rahimi as discussed so far, does not teach the at least one heat transfer element extends axially within a corresponding one of the hollow vanes.
However, Marchaj further teaches the at least one heat transfer element (section 115 of central strut 110 of the set of 3 struts forming the hollow vane; and/or 109, 120 within the section 115) extends axially within a corresponding one of the hollow vanes (Figs 4, 6; 115, 109, 120 all having an axial extent along axis X between the adjacent struts 110).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the engine of Powell in view of Marchaj and Rahimi to include the heat transfer element of Marchaj, in order to mitigate ice accumulation at the engine inlet which can adversely impact engine operation (Marchaj, [0003])
Regarding claim 12, Powell teaches a method of operating a turbofan gas turbine engine (10), the gas turbine engine comprising,
an outer housing (48); and
in axial flow sequence an inlet duct (49 of 48), a fan assembly (14), a compressor module (16), and a turbine module (20, 22), and an exhaust module (58, 60),
the fan assembly comprising a plurality of fan blades (34, 38, 44) defining a fan diameter (D; defined by 34, 38, or 44),
the method comprising:
(i) providing the fan assembly, the compressor module, and the turbine module, and the exhaust module within the outer housing (Figs 1-5);
(ii) providing the inlet with a substantially square radial cross-sectional profile that is an overall shape of the inlet (Figs 2, 5), where a side length of the substantially square cross-section is D (Figs 2, 5); and
(iii) positioning the inlet in fluid communication with the fan assembly (Fig 1) such that an airflow passes into the inlet prior to flowing to the fan assembly (Figs 1-5).
Powell does not teach a heat exchanger module upstream of, and in fluid communication with, the fan assembly via the inlet duct; the heat exchanger module within the outer housing; the heat exchanger module configured to cool the engine and having the substantially square radial cross-sectional profile as an overall shape, the substantially square radial cross-sectional profile being in the form of a super-ellipse; (iv) providing the heat exchanger module with a plurality of radially-extending hollow vanes arranged in an equispaced circumferential array with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially-extending hollow vanes, the hollow vanes each include a hollow portion through which a portion of the airflow passes, at least one of the hollow vanes accommodating at least one heat transfer element in the hollow portion for transfer of heat energy from a first fluid contained within the at least one heat transfer element to a the portion of the airflow passing through the hollow vane and over a surface of the at least one heat transfer element, and a circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes; and (v) operating the gas turbine engine such that the portion of the airflow enters the hollow portion before passing over the surface of the at least one heat transfer element.
However, Marchaj teaches a method of operating a turbofan gas turbine engine (Fig 1),
the gas turbine engine comprising an outer housing (62) and, in axial flow sequence, a heat exchanger module (incl.110), an inlet duct (defined by portion of 15, 62 from 110 to 42), a fan assembly (incl.42), a compressor module (incl. 44, 52), a turbine module (54, 46), and an exhaust module (aft of turbine; [0038]),
the fan assembly comprises a plurality of fan blades (42) defining a fan diameter (D, from tip to tip, intersecting centerline X),
the method comprising:
(i) providing the fan assembly, the compressor module, and the turbine module, and the exhaust module within the outer housing (Fig 1);
(ii) providing the heat exchanger module with a radial cross-sectional profile within the outer housing and conforming to the shape of the outer housing (Figs 1, 4), the radial cross-sectional profile being an overall shape of the heat exchanger module within the outer housing (Figs 1, 4), wherein a largest cross-sectional dimension of the heat exchanger module is D (Fig 1), and the heat exchange module configured to cool the engine (heat exchange module being wholly contained in the engine, at least one of the fluids/structures of/in the heat exchange module being cooled);
(iii) positioning the heat exchanger module in fluid communication with the fan assembly by the inlet duct (Fig 1);
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(iv) providing the heat exchanger module with a plurality of radially-extending hollow vanes (a set of three struts 110 considered to read on a hollow vane per Fig 4 above; Figs 1, 5-6) arranged in a circumferential array with a channel extending axially between each pair of adjacent hollow vanes of the plurality of radially-extending hollow vanes (Fig 4),
the hollow vanes each include a hollow portion (between every other strut per Fig 4 below) through which a portion of an airflow passes prior to flowing to the fan assembly (Figs 1, 5),
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at least one of the hollow vanes accommodating at least one heat transfer element (at least portion 115 of the central strut of each set of struts further comprising at least 120, 109) in the hollow portion for transfer of heat energy from a first fluid (114) contained within the at least one heat transfer element to the portion of the airflow passing through the hollow vane and over a surface (suction and pressure sides of central strut 100 of the set of struts) of the at least one heat transfer element (Figs 1, 4-6), and a circumferential space between adjacent ones of the hollow vanes is greater than a circumferential span of one of the hollow vanes (interpreted under 112b discussion above as referring to any dimension of the space and any circumferential span of the hollow vanes; looking to Fig 4, the circumferential span of each hollow vane at some point toward the radially inner end of the vane is smaller than the largest radial and circumferential dimensions of the space between the hollow vanes); and
operating the gas turbine engine such that the portion of the airflow enters the hollow portion before passing over the surface of the at least one heat transfer element (air enters past leading edges 122 of every other strut, before passing over portion 115 of the central strut of each set of three struts forming the hollow vane).
Although Fig 4 of Marchaj depicts 11 struts, paragraph [0048] teaches more, or fewer may be utilized, and using just one more strut or two fewer struts provides equispacing to the circumferential array. Furthermore, MPEP 2144.05(I) provides that a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close.
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the engine of Powell to include the heat exchanger module of Marchaj, in order to mitigate ice accumulation at the engine inlet which can adversely impact engine operation (Marchaj, [0003]). Note, the resulting engine of Powell in view of Marchaj is characterized by the heat exchanger module having an overall shape that is a square radial cross-sectional profile.
Claims 2, 4, 8-9, and 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi.
Regarding claim 2, both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach all the limitations of the claimed invention as discussed above. Powell further teaches the substantially square radial cross-section profile comprises a side length E that is equal to or greater than D (or 1.0*D; measured from any of 34, 38, 44) and less than 1.5*D (Figs 1-8).
Regarding claims 4 and 13, both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach all the limitations of the claimed invention as discussed above. Powell further teaches each corner of the substantially square cross-sectional profile comprises a curved profile (Figs 2, 5).
Regarding claim 8, both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach all the limitations of the claimed invention as discussed above. Powell further teaches the heat exchanger module has a flow area AHEX and the fan module has a flow area AFAN, and a ratio of AFAN to AHEX being is 0.6 to 1.0 (for a concentric circle and square, sharing at least one point on each side of the square, the ratio of circle area to square area is am = 0.785, where R is the radius of the circle equal to half the diameter, thus any reduction in area due to curvature of the corners increases the ratio up to 1, where the square becomes the circle).
Regarding claim 9, both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach all the limitations of the claimed invention as discussed above. Powell further teaches the fan assembly has two fan stages (34, 38), at least one of the fan stages comprising a plurality of fan blades defining the fan diameter D (as discussed previously, either one of 34 or 38 may define diameter D).
Claim 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi, each in further view of Garrick WO0229224A1.
Regarding claim 5, both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach all the limitations of the claimed invention as discussed above. Neither Powell in view of Suciu and Rahimi nor Powell in view of Marchaj and Rahimi teach each one of the four corner regions of the cross-sectional profile of the heat exchanger module accommodates one of the hollow vanes.
However, Garrick teaches adjusting a circumferential distribution of vanes in a circular cross-section (Figs 1-2 and 5-10) to be in a square cross-section (Fig 16a) while arranging a vane at each corner of the square cross-section (Fig 16a).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the circumferential distribution of vanes in the square cross-section of both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi to include a vane at each corner of the square cross-section as taught by Garrick, because Applicant has not demonstrated criticality of this feature (only page 22 of Applicant’s Specification describes the claimed “corner” vanes and there is no discussion of criticality), and: MPEP2144.04(IV)(B) provides that changes in shape are an obvious extension of prior art teachings absent evidence that the particular claimed configuration was significant (in this case, neither Applicant’s disclosure nor the prior art provides any evidence of significance of the claimed arrangement, also taught by Garrick’s Fig 16a); MPEP2144.04(VI)(C) provides that rearrangement of parts was an obvious extension of prior art teachings when the rearrangement would not have modified the operation of the claimed apparatus (in this case, neither Applicant’s disclosure nor the prior art provides any evidence that the claimed arrangement provides any difference in operation).
Claims 7 and 14-15 is/are rejected under 35 U.S.C. 103 as being unpatentable over both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi, each in further view of Wikipedia (“Turbofan engine”, https://en.wikipedia.org/wiki/Turbofan_engine , published 21 August 2019).
Regarding claims 7 and 14-15, both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach all the limitations of the claimed invention as discussed above. Neither Powell in view of Suciu and Rahimi nor Powell in view of Marchaj and Rahimi as discussed so far, teach the fan diameter D is within (claim 7) 0.3m to 2.0m, (claim 1574) 0.4-1.5m, or (claim 15) 0.7-1.0m.
However, fan diameters in this range were known. see Wikipedia page for “Turbofan” (section “Commercial Turbofans in Production”) teaching fan diameters from 0.36 - 3.25m, including specific examples of 0.70m and 0.97m.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the turbofans of both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi have a fan diameter between (claim 7) 0.3 and 2.0m, (claim 14) 0.4m to 1.5m, and (claim 15) 0.7m to 1.0m, as taught by Wikipedia’s known turbofan diameters, because MPEP2144.04(IV)(A) provides that limitations relating to the size of an apparatus (i.e. such that fan diameter is 0.3-2.0, 0.4-1.5, and 0.7-1.0m) are not sufficient to patentably distinguish over the prior art (i.e. both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teaching all the other claimed structures) because mere scaling up (or down) of a prior art apparatus (i.e. both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach turbofans of nondescript size) capable of being scaled up (i.e. Wikipedia teaching known turbofans with fan diameters from 0.36-3.25m) does not establish patentability in a claim to an old apparatus (i.e. claim 1 taught by both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi) so scaled (i.e. per claims 7, 14, or 15). Thus, where the only difference between the prior art (i.e. both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teaching all other claimed structural limitations) and the claims (i.e. claims 7 and 14-15) was a recitation of relative dimensions of the claimed device (i.e. turbofan fan diameter 0.3-2.0, 0.4-1.5, and 0.7-1.0m) and a device having the claimed relative dimensions would not perform differently than the prior art device (i.e. per Wikipedia teaching known turbofans of diameter 0.36-3.25m), the claimed device (i.e. claims 7 and 14-15) was not patentably distinct from the prior art device (Powell in view of Suciu, Rahimi, and Wikipedia ; and Powell in view of Marchaj, Rahimi, and Wikipedia).
Claim 11 is/are rejected under 35 U.S.C. 103 as being unpatentable over both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi, each in further view of Shetty FR2629517.
Regarding claim 11, both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi teach all the limitations of the claimed invention as discussed above.
Powell further teaches a method of operating an aircraft comprising the gas turbine engine as claimed in Claim 1 (Col.2 ll.60-end), to take off from a runway, wherein there is a maximum rotational speed of the turbine during take-off (the engine being an aircraft engine, is used for takeoff of the aircraft, Col.1 l.8; the turbine rotating during engine operation, comprises a maximum speed at takeoff).
Neither Powell in view of Suciu and Rahimi nor Powell in view of Marchaj and Rahimi as discussed so far, teach the maximum rotational speed is in the range of from 12400 rpm to 24700 rpm.
However, Shetty (FR) teaches a known turbofan take-off turbine maximum rotational speed may be 14100rpm (p.2 ll.52-54).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to operate the turbofans of both Powell in view of Suciu and Rahimi and Powell in view of Marchaj and Rahimi with a high pressure turbine speed of up to 14100rpm as taught by Shetty, in order to provide sufficient acceleration for takeoff of the aircraft (Shetty, p.2 ll.52-54).
Potentially Allowable Subject Matter
Claim 3 is rejected for being dependent upon a rejected base claim under 112b, but may be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims, while overcoming the 112b rejection.
Response to Arguments
Applicant's arguments filed 31 December 2025 have been fully considered but they are not persuasive.
Regarding the super-ellipse limitations, new prior art reference Rahimi provides evidence of the substitutional equivalence of rounded squares and square super-ellipses (or squircles).
Regarding equidistant spacing in Marchaj, (as discussed above) although Marchaj teaches only 11 struts in Fig 4, paragraph [0048] teaches using more or less struts as desired, and MPEP 2144.05(I) provides that a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close.
Regarding the remaining arguments/limitations in Remarks filed 31 December 2025, these were addressed in the Advisory Action mailed 08 January 2026.
Correspondence
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/STEPHANIE SEBASCO CHENG/Primary Examiner, Art Unit 3741