A gas turbine engine defining a centerline and a circumferential direction, the gas turbine engine including: a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the turbomachine defining a working gas flowpath and a fan duct flowpath; a primary fan driven by the turbomachine defining a primary fan tip radius R.sub.1 and a primary fan hub radius R.sub.2; a secondary fan located downstream of the primary fan and driven by the turbomachine, at least a portion of an airflow from the primary fan configured to bypass the secondary fan, the secondary fan defining a secondary fan tip radius R.sub.3 and a secondary fan hub radius R.sub.4, wherein the secondary fan is configured to provide a fan duct airflow through the fan duct flowpath during operation to generate a fan duct thrust, wherein the fan duct thrust is equal to % Fn.sub.3S of a total engine thrust during operation of the gas turbine engine at a rated speed during standard day operating conditions; wherein a ratio of R.sub.1 to R.sub.3 equals $\sqrt{\left(\mathrm{EFP}\right)\frac{\left(1-Rq{R}_{\mathrm{Sec}.-{\mathrm{Fan}}^2}\right)}{\left(1-Rq{R}_{\mathrm{Prim}.-\mathrm{Fa}{n}^2}\right)}\left(\frac{1}{\%{\mathrm{Fn}}_{3S}}-1\right)}$

A gas turbine engine defining a centerline and a circumferential direction, the gas turbine engine including: a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the turbomachine defining a working gas flowpath and a fan duct flowpath; a primary fan driven by the turbomachine defining a primary fan tip radius R.sub.1 and a primary fan hub radius R.sub.2; a secondary fan located downstream of the primary fan and driven by the turbomachine, at least a portion of an airflow from the primary fan configured to bypass the secondary fan, the secondary fan defining a secondary fan tip radius R.sub.3 and a secondary fan hub radius R.sub.4, wherein the secondary fan is configured to provide a fan duct airflow through the fan duct flowpath during operation to generate a fan duct thrust, wherein the fan duct thrust is equal to %Fn.sub.3S of a total engine thrust during operation of the gas turbine engine at a rated speed during standard day operating conditions; wherein a ratio of R.sub.1 to R.sub.3 equals

[00001]$\sqrt{\left(EFP\right)\frac{\left(1-Rq{R}_{sec.-Fan}{}^2\right)}{\left(1-Rq{R}_{Prim.-Fan}{}^2\right)}\left(\frac{1}{\%F{n}_{3s}}-1\right)};$

wherein EFP is between 1.5 and 11, wherein RqRp.sub.rim.-Fan is a ratio of R.sub.1 to R.sub.2, and wherein RqR.sub.Sec.-Fan is a ratio of R.sub.3 to R.sub.4.

A method of optimizing probe placement in a turbomachine is disclosed which includes determining wavenumber (Wn) of N dominant wavelets generated by upstream and downstream stators and blade row interactions formed around an annulus, establishing a design matrix A utilized in developing flow properties around the annulus having a dimension of m×(2N+1), iteratively modifying probe positions placed around the annulus and determining a condition number of the design matrix A for each set of probe positions until a predetermined threshold is achieved for the condition number representing optimal probe position, wherein the condition number is defined as norm A.Math.norm A+, wherein A+ represents inverse of A for a square matrix and a Moore-Penrose pseudoinverse of A for a rectangular matrix.

The method can include determining a mass flow rate W of working fluid circulating through the compressor stage, determining a control parameter value associated to the geometrical configuration of the variable geometry element based on the determined value of mass flow rate W; and changing the geometrical configuration of the variable geometry element in accordance with the determined control parameter value.

A control system for limiting a power turbine torque of a gas turbine engine is disclosed. In various embodiments, the control system includes an engine control module configured to output an effector command signal to a gas generator of the gas turbine engine; a power turbine governor module configured to output to the engine control module a power turbine torque request signal; and a power turbine torque limiter module configured to output to the power turbine governor module a power turbine speed rate signal to limit a power turbine speed overshoot of the gas turbine engine.

The method can include determining a mass flow rate W of working fluid circulating through the compressor stage, determining a control parameter value associated to the geometrical configuration of the variable geometry element based on the determined value of mass flow rate W; and changing the geometrical configuration of the variable geometry element in accordance with the determined control parameter value.

A method of optimizing probe placement in a turbomachine is disclosed which includes establishing a design matrix A of size m×(2N+1) utilized in developing flow properties around an annulus of a turbomachine, where m represents the number of datapoints at different circumferential locations around the annulus, and N represents dominant wavelets generated by upstream and downstream stators and blade row interactions formed around an annulus, wherein m is greater or equal to 2N+1, and optimizing probe positioning by iteratively modifying probe positions placed around the annulus and for each iteration determining a condition number of the design matrix A for each set of probe positions until a predetermined threshold is achieved for the condition number representing an optimal probe layout.

A gas turbine is provided, the gas turbine engine including a turbomachine having an inlet splitter defining in part an inlet to a working gas flowpath and a fan duct splitter defining in part an inlet to a fan duct flowpath. The gas turbine engine also includes a primary fan driven by the turbomachine defining a primary fan tip radius R1, a primary fan hub radius R2, and a primary fan specific thrust rating TP; and a secondary fan downstream of the primary fan and driven by the turbomachine, the secondary fan defining a secondary fan tip radius R3, a secondary fan hub radius R4, and a secondary fan specific thrust rating TS; wherein the gas turbine engine defines an Effective Bypass Area, and wherein a ratio of R1 to R3 equals

[00001]$\frac{R_1}{R_3}=\sqrt{\left(\mathrm{EFP}\right)\frac{\left(1-{\mathrm{RqR}}_{\left(\mathrm{Sec}.-\mathrm{Fan}\right)}^2\right)}{\left(1-{\mathrm{RqR}}_{\mathrm{Prim}.-\mathrm{Fan}}^2\right)}\left(\frac{T_P}{T_S}\right)\left(\mathrm{EBA}\right)}.$

A method of optimizing probe placement in a turbomachine is disclosed which includes establishing a design matrix A of size m×(2N+1) utilized in developing flow properties around an annulus of a turbomachine, where m represents the number of datapoints at different circumferential locations around the annulus, and N represents dominant wavelets generated by upstream and downstream stators and blade row interactions formed around an annulus, wherein m is greater or equal to 2N+1, and optimizing probe positioning by iteratively modifying probe positions placed around the annulus and for each iteration determining a condition number of the design matrix A for each set of probe positions until a predetermined threshold is achieved for the condition number representing an optimal probe layout.

A method of optimizing probe placement in a turbomachine is disclosed which includes determining wavenumber (Wn) of N dominant wavelets generated by upstream and downstream stators and blade row interactions formed around an annulus, establishing a design matrix A utilized in developing flow properties around the annulus having a dimension of m×(2N+1), iteratively modifying probe positions placed around the annulus and determining a condition number of the design matrix A for each set of probe positions until a predetermined threshold is achieved for the condition number representing optimal probe position, wherein the condition number is defined as norm A.Math.norm A+, wherein A+ represents inverse of A for a square matrix and a Moore-Penrose pseudoinverse of A for a rectangular matrix.