Gas Turbine Engine Cooling and Acoustic Spacing for High-Temperature Thrust
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Solution Overview
Problem
Conventional turbofan engine designs face challenges in operating at higher temperatures due to high temperatures at the exit stage of the high pressure compressor, which can lead to prohibitively high temperatures at the turbine section inlet and exhaust section, limiting compressor pressure ratio and thrust output, while also generating significant noise.
Innovation Solution
Incorporation of a cooled cooling air system to reduce the temperature of airflow using a heat exchanger, combined with specific acoustic spacing between fan blades and outlet guide vanes to reduce noise and maintain performance, allowing the engine to operate at higher temperatures and increase thrust output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor pressure ratio is increased to improve thrust output, then the engine can generate more thrust, but the temperature at the turbine section inlet and exhaust section becomes prohibitively high
Solution Approach 1:
The patent divides the cooling function into multiple stages by introducing cooling air at different locations (compressor inlet and compressor outlet) and using separate cooling passages for different turbine components. This segmented cooling approach allows effective temperature control without limiting the compressor pressure ratio, thereby resolving the contradiction between thrust output and turbine inlet temperature.
Solution Approach 2:
The patent applies preliminary cooling by introducing cooling air into the compressor inlet and outlet before the air enters the combustor. This pre-cooling of the compression air reduces the temperature of air entering the combustor, which in turn reduces the turbine inlet temperature, allowing higher compressor pressure ratios without exceeding temperature limits.
2Use of energy by moving object
If the engine operates at higher temperatures to increase efficiency, then propulsive efficiency improves, but noise generation increases significantly
Solution Approach 1:
The patent introduces acoustic treatment material as an intermediary between the high-temperature exhaust gases and the external environment. This material absorbs and attenuates noise generated by high-temperature operation, allowing the engine to maintain high propulsive efficiency through higher operating temperatures while significantly reducing the noise that propagates outward.
3Temperature
If cooling air is introduced to reduce turbine temperature, then turbine inlet temperature is controlled, but compressor pressure ratio is limited
Solution Approach 1:
The patent segments the cooling air supply into multiple sources (compressor inlet cooling and compressor outlet cooling) and multiple delivery paths (separate cooling passages for different turbine components). This segmentation allows sufficient cooling air to be provided to control turbine inlet temperature while maintaining high compressor pressure ratio, as the cooling air is drawn from different stages of compression and delivered through dedicated passages.
Solution Approach 2:
The patent applies preliminary cooling at the compressor inlet and outlet before the air enters the combustor. This pre-cooling reduces the temperature of compression air, allowing the compressor to achieve higher pressure ratios without resulting in excessively high turbine inlet temperatures, thus resolving the contradiction between temperature control and pressure ratio maintenance.
4Object-generated harmful factors
If acoustic treatment material is added to reduce noise, then noise propagation is attenuated, but device complexity increases
Solution Approach 1:
The patent merges the acoustic treatment material directly into the exhaust nozzle structure, combining the noise reduction function with the existing exhaust system components. This integration approach reduces device complexity compared to adding separate acoustic treatment systems, as the acoustic material becomes part of the exhaust nozzle assembly rather than a separate component.
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 cooled cooling air system maintains or increases maximum turbofan engine thrust output while reducing noise and aerodynamic drag, achieving improved propulsive efficiency and noise reduction.
Implementation Method 1
the cooled cooling air system includes a heat exchanger configured to transfer heat from the cooling airflow to a heat sink
Implementation Method 2
The engine includes acoustic treatment material disposed within the exhaust system downstream of the turbine
Data Source
AI summary
A gas turbine engine is provided. The gas turbine engine includes: a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order, the compressor section having a high pressure compressor defining a high pressure compressor exit area (AHPCExit) in square inches; wherein the gas turbine engine defines a redline exhaust gas temperature (EGT) in degrees Celsius, a total sea level static thrust output (FnTotal) in pounds, and a corrected specific thrust, wherein the corrected specific thrust is greater than or equal to 42 and less than or equal to 90, the corrected specific determined as follows: FnTotal×EGT/(AHPCExit2×1000). The gas turbine engine further includes a blade effective acoustic length (BEAL), an acoustic spacing, and an acoustic spacing ratio (ASR). The ASR can be in a range from 1.5 to 16.0.