Compressor Rotor Design for High Pressure Ratio
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Solution Overview
Problem
Gas turbine engine designers face challenges in improving compressor section performance and reducing overall weight while maintaining or increasing pressure ratio and rotational speeds, limited by material choices that balance strength, weight, and temperature capability.
Innovation Solution
A gas turbine engine design featuring a compressor rotor with a first stage compressor airfoil made of high-strength materials like nickel-based alloys, optimized for high tip speeds and pressure ratios, and reduced axial stages to eliminate the need for low- or intermediate-pressure compressors, coupled with innovative bearing assemblies and structural members for weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nickel-based materials are used in the compressor rotor to increase strength and temperature capability, then the strength and temperature resistance improve, but the engine weight increases
Solution Approach 1:
The patent applies different material qualities to different locations within the compressor rotor. The first stage compressor airfoil is made of nickel-based superalloy for high strength and temperature capability, while other portions can use lighter materials. This local differentiation allows the engine to achieve necessary strength where required without unnecessarily increasing overall weight.
Solution Approach 2:
The compressor rotor is constructed using composite material architecture, combining nickel-based superalloy for the first stage airfoil with other materials for remaining sections. This composite approach optimizes the balance between strength requirements and weight minimization by selecting materials based on local operational demands.
2Weight of moving object
If the number of axial stages is reduced to decrease engine weight and dimensions, then the weight and size reduce, but the pressure ratio capability may be compromised
Solution Approach 1:
The patent changes key operational parameters of the compressor rotor, specifically increasing rotational speed and optimizing the first stage pressure ratio to at least 1.7. By operating at higher speeds and optimizing stage characteristics, the compressor achieves required overall pressure ratios with fewer axial stages, thereby reducing weight and dimensions while maintaining performance.
Solution Approach 2:
The invention employs dynamic operation at high rotational speeds to compensate for reduced stage count. The compressor rotor is designed to operate optimally at elevated speeds, where centrifugal forces and aerodynamic effects enhance pressure generation per stage, allowing fewer stages to achieve the same overall pressure ratio.
3Stress or pressure
If the first stage compressor airfoil tip speed is increased to at least 472 meters per second to improve pressure ratio, then the pressure ratio improves, but the stress and centrifugal forces on the rotor increase
Solution Approach 1:
The first stage compressor airfoil employs optimized curved geometry with specific radius ratios (inner radius to outer radius less than 0.4). This curved design efficiently manages the high centrifugal forces generated at tip speeds of at least 472 meters per second while maintaining effective compression. The aerodynamic shaping distributes stresses more favorably across the airfoil structure.
Solution Approach 2:
The high-stress first stage airfoil is constructed from nickel-based superalloy materials that provide the necessary strength-to-density ratio (at least 0.18) to withstand centrifugal forces at high rotational speeds. This material selection enables the rotor to safely operate at the required tip speeds to achieve the target pressure ratio.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves higher rotational speeds and pressure ratios while minimizing engine weight, improving performance and enabling integration into various engine types, such as dual-cycle engines, with reduced part counts and dimensions, and enhanced operational efficiency.
Implementation Method 1
a first stage compressor airfoil defining a first stage pressure ratio of at least approximately 1.7 during operation of the gas turbine engine at a tip speed of at least approximately 472 meters per second
Data Source
AI summary
The present disclosure is directed to a gas turbine engine including a first frame comprising a first bearing assembly, a second frame comprising a second bearing assembly, and a compressor rotor. A first stage compressor airfoil is defined at an upstream-most stage of the compressor rotor. The compressor rotor is rotatable via the first bearing assembly and the second bearing assembly. The first stage compressor airfoil is disposed between the first bearing assembly and the second bearing assembly.