Combustor Cooling Air Pump Layout for Compact Gas Turbines
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Solution Overview
Problem
Small gas turbine engines face challenges with combustor designs that limit altitude relight capabilities, reverse flow designs that decrease energy recovery, and fuel injection systems that require larger packages and separate pumps, along with ignitor positioning that results in an undesirably long combustor.
Innovation Solution
The design includes a combustor with a toroidal recirculation zone, quench and lean combustion zones, and integrated shaft cooling air pump to enhance cooling, combined with additive manufacturing for compact construction, and a shaft that transmits rotational energy and pumps fuel, eliminating the need for separate fuel pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate fuel pump and manifold are used for fuel injection, then fuel delivery is reliable, but the engine package size increases and device complexity increases
Solution Approach 1:
The fuel injection system is merged with the compressor assembly. The fuel pump is integrated into the compressor housing, and the fuel injection nozzle is positioned within the compressor outlet area, eliminating the need for a separate fuel pump and manifold while maintaining reliable fuel delivery throughout the compression and combustion process
Solution Approach 2:
The compressor housing serves multiple functions: it compresses the gas, houses the fuel pump, provides mounting for the fuel injection nozzle, and directs both compressed gas and fuel to the combustion chamber. This multi-functionality reduces the number of separate components needed in the system
2Reliability
If the combustor is designed with traditional ignitor positioning, then ignition is reliable, but the combustor length increases
Solution Approach 1:
The ignitor is repositioned from a traditional axial location at the combustor inlet to a radial position on the combustor wall. This dimensional change allows the ignition source to be distributed around the combustor periphery, enabling reliable ignition while maintaining a compact axial length
3Volume of moving object
If reverse flow design is used in the combustor, then compact packaging is achieved, but energy recovery decreases
Solution Approach 1:
The combustor is divided into distinct functional zones: a primary combustion chamber for fuel combustion, a quench zone for rapid cooling of combustion products, and a secondary combustion zone for completing the combustion process. This segmentation allows compact packaging while maintaining efficient energy recovery through controlled flow paths in each zone
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
This design achieves improved operability, lean blow out characteristics, and enhanced operational life with compact packaging, supporting high altitude relight capability and efficient energy recovery.
Implementation Method 1
to further compress the second portion of the compressed air in the turbine air plenum before the second portion of the compressed air enters the combustor as fuel injector air and combustor secondary inlet air
Implementation Method 2
A cooling air flow path is configured to direct a second portion of the compressed air around the outer combustor liner to cool the combustor liner
Data Source
AI summary
A gas turbine engine includes a compressor configured to receive inlet air at a compressor inlet and generate compressed air at a compressor exit, a combustor positioned fluidically and physically downstream of the compressor, a turbine positioned fluidically and physically downstream of the combustor, and a shaft mechanically connecting the turbine and the compressor. The combustor is fluidically connected to the compressor to receive a first portion of the compressed air as combustor primary inlet air. The combustor includes a combustor liner having an inner combustor liner and an outer combustor liner, surrounding one or more combustion zones. A cooling air flow path is configured to direct a second portion of the compressed air around the outer combustor liner to cool the combustor liner and to provide a source of quench air, inner combustor liner cooling air, fuel injector air, and combustor secondary inlet air.