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A method of manufacturing a compressor section includes the steps of defining a compressor section having a number of blades, and having one or more stator sections, each with numbers of vanes. Each stator section has at least two sections wherein the spacing between the vanes in a first of the sect

A method of manufacturing a compressor section includes the steps of defining a compressor section having a number of blades, and having one or more stator sections, each with numbers of vanes. Each stator section has at least two sections wherein the spacing between the vanes in a first of the sections is not equal to a spacing between the vanes in a second of the sections. The number of blades, and the number of vanes where all of the sections are selected to achieve acoustic cutoff.

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1. A method of manufacturing a compressor section comprising the steps of: defining a compressor section having a first number of blades, and at least one stator section having a number of vanes, with each stator section having at least two sections wherein a spacing between the vanes in a first of

1. A method of manufacturing a compressor section comprising the steps of: defining a compressor section having a first number of blades, and at least one stator section having a number of vanes, with each stator section having at least two sections wherein a spacing between the vanes in a first of the sections is not equal to a spacing between the vanes in a second of the sections;selecting the number of blades, and the number of vanes in at least one of the sections to achieve cutoff; anda minimum absolute value for a quantity m is utilized to calculate whether the compressor will achieve cutoff, and wherein m=nB−2 kV, wherein V is equal to the number of vanes in the one of the two subsections, n is the blade passing frequency harmonic, which is an integer, B is the number of blades, and k is a vane passing frequency harmonic order, which is an integer. 2. The method as set forth in claim 1, wherein a calculation is performed that assumes that air flow through the compressor will be generally axial. 3. The method as set forth in claim 2, wherein the following formula is utilized to determine if the compressor will achieve cutoff: ξ=nBMtmMm⁢⁢μ*⁢1-Mx2<1ξ=cutoff ration=Blade passing frequency harmonic order (any integer from 1 to infinity)B=Number of compressor rotor bladesk=Vane passing frequency harmonic order (any integer from −infinity to infinity)V=Number of compressor vanes upstream and/or downstream of the compressor rotor Mt=Local⁢⁢tip⁢⁢rotational⁢⁢Mach⁢⁢number=Ω⁢⁢rc0Ω=Rotor rotational speed (rad/sec)r=Local tip duct radiusc0=Local speed of soundMx=Mean local axial Mach number in the duct Mm⁢⁢μ*=κm⁢⁢μm=Cutoff⁢⁢Mach⁢⁢numberκmμ=Mode Eigenvalue for a given (m, μ) mode normalized by rμ=Radial mode order (integer from 0 to infinity) (set=0 for the purposes of this calculation). 4. The method as set forth in claim 1, wherein a determination is made that assumes the effect of swirl on air flow through the compressor. 5. The method as set forth in claim 4, wherein the following formula is utilized to determine if the compressor will achieve cutoff: ξ=nBMt-mMsmMm⁢⁢μ*⁢1-Mx2<1ξ=cutoff ration=Blade passing frequency harmonic order (any integer from 1 to infinity)B=Number of compressor rotor bladesk=Vane passing frequency harmonic order (any integer from −infinity to infinity)V=Number of compressor vanes upstream and/or downstream of the compressor rotor Mt=Local⁢⁢tip⁢⁢rotational⁢⁢Mach⁢⁢number=Ω⁢⁢rc0Ω=Rotor rotational speed (rad/sec)r=Local tip duct radiusc0=Local speed of soundMs=is a local swirl flow Mach number in between two rows of vanes and/or blades, and positive being defined in the direction of rotor rotation, and wherein the Ms component is calculated by taking the swirl velocity and dividing it by the c0 valueMx=Mean local axial Mach number in the duct Mm⁢⁢μ*=κm⁢⁢μm=Cutoff⁢⁢Mach⁢⁢numberκmμ=Mode Eigenvalue for a given (m, μ) mode normalized by rμ=Radial mode order (integer from 0 to infinity) (set =0 for the purposes of this calculation). 6. A compressor comprising: a rotor having a plurality of blades;at least one stator section having a plurality of vanes, with there being at least two subsections to each stator section, and a spacing between said vanes in a first of said subsections is unequal to a spacing between vanes in a second of said subsections, and the number of vanes being selected in combination with the number of blades in the rotor to achieve cutoff;a minimum absolute value for a quantity m is utilized to calculate whether the compressor will achieve cutoff, and wherein m=nB−2 kV, wherein V is equal to the number of vanes in the one of the two subsections, n is the blade passing frequency harmonic, which is an integer, B is the number of blades, and k is a vane passing frequency harmonic order, which is an integer. 7. The compressor as set forth in claim 6, wherein a calculation is performed to ensure cut-off is achieved that assumes that air flow through the compressor will be generally axial. 8. The compressor as set forth in claim 7, wherein the following formula is met to ensure the compressor will achieve cutoff: ξ=nBMtmMm⁢⁢μ*⁢1-Mx2<1ξ=cutoff ration=Blade passing frequency harmonic order (any integer from 1 to infinity)B=Number of compressor rotor bladesk=Vane passing frequency harmonic order (any integer from −infinity to infinity)V=Number of compressor vanes upstream and/or downstream of the compressor rotor Mt=Local⁢⁢tip⁢⁢rotational⁢⁢Mach⁢⁢number=Ω⁢⁢rc0Ω=Rotor rotational speed (rad/sec)r=Local tip duct radiusc0=Local speed of soundMx=Mean local axial Mach number in the duct Mm⁢⁢μ*=κm⁢⁢μm=Cutoff⁢⁢Mach⁢⁢numberκmμ=Mode Eigenvalue for a given (m, μ) mode normalized by rμ=Radial mode order (integer from 0 to infinity) (set=0 for the purposes of this calculation). 9. The compressor as set forth in claim 6, wherein a determination is made that assumes the effect of swirl on air flow through the compressor. 10. The compressor as set forth in claim 9, wherein the following formula is utilized to determine if the compressor will achieve cutoff: ξ=nBMt-mMsmMm⁢⁢μ*⁢1-Mx2<1ξ=cutoff ration=Blade passing frequency harmonic order (any integer from 1 to infinity)B=Number of compressor rotor bladesk=Vane passing frequency harmonic order (any integer from −infinity to infinity)V=Number of compressor vanes upstream and/or downstream of the compressor rotor Mt=Local⁢⁢tip⁢⁢rotational⁢⁢Mach⁢⁢number=Ω⁢⁢rc0Ω=Rotor rotational speed (rad/sec)r=Local tip duct radiusc0=Local speed of soundMs=is a local swirl flow Mach number in between two rows of vanes and/or blades, and positive being defined in the direction of rotor rotation, and wherein the Ms component is calculated by taking the swirl velocity and dividing it by the c0 valueMx=Mean local axial Mach number in the duct Mm⁢⁢μ*=κm⁢⁢μm=Cutoff⁢⁢Mach⁢⁢numberκmμ=Mode Eigenvalue for a given (m, μ) mode normalized by rμ=Radial mode order (integer from 0 to infinity) (set=0 for the purposes of this calculation).