Intercooled Cooling Air Bypass Dump for Low-Power Surge Control
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Solution Overview
Problem
In gas turbine engines, particularly with high-bypass geared architectures, there is a need to efficiently utilize cooling air while avoiding undesirable operational conditions such as compressor surge during lower power operations, which can occur due to increased pressure ratios.
Innovation Solution
A control system is implemented to selectively dump air downstream of a cooling compressor, utilizing a dual-valve arrangement that automatically adjusts based on pressure differences to either direct cooling air to the turbine section or divert it into the bypass flow during lower power operations, preventing compressor surge and ensuring efficient air utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is delivered to the compressor section and turbine section, then cooling effectiveness is improved, but compressor surge may occur during lower power operations
Solution Approach 1:
The system dynamically adjusts the cooling air distribution by switching between two operational modes: a first mode during higher power operations where cooling air is delivered to both compressor and turbine sections, and a second mode during lower power operations where cooling air is delivered only to the turbine section. This dynamic adaptation prevents compressor surge while maintaining cooling effectiveness when needed.
Solution Approach 2:
The control system monitors engine operating parameters (such as N2 speed and temperature differential) and changes the cooling air distribution parameters accordingly. By adjusting the flow path configuration based on real-time parameter monitoring, the system optimizes cooling effectiveness while preventing harmful compressor surge conditions.
2Reliability
If a dual-valve arrangement is used to control cooling air distribution, then compressor surge is prevented, but device complexity increases
Solution Approach 1:
The dual-valve arrangement operates automatically based on monitored engine parameters without requiring external control intervention. The valves self-adjust the cooling air distribution by responding to pressure differentials and flow conditions, thereby preventing compressor surge while minimizing the need for complex external control systems.
Solution Approach 2:
The control system extracts and monitors specific critical parameters (such as temperature differential and compressor speed) to determine when to switch between cooling modes. By focusing control on key parameters rather than managing all system variables, the complexity of the control arrangement is reduced while maintaining effective surge prevention.
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 solution enhances engine efficiency by managing cooling air distribution, preventing compressor surge and optimizing air usage across varying power conditions, thereby improving overall engine performance and reducing fuel consumption.
Implementation Method 1
A first valve upstream of the mixing chamber and a second valve downstream of the mixing chamber automatically open or close depending on pressure differences
Data Source
Figure 1
Figure 2~4
AI summary
A gas turbine engine (101) includes a main compressor section (102) having a downstream most location (104), and a turbine section (108), with both the main compressor section (102) and the turbine section (108) housing rotatable components. A first tap (110) taps air compressed by the main compressor section (102) at an upstream location upstream of the downstream most location (104). The first tap (110) passes through a heat exchanger (112) and to a cooling compressor (114). Air downstream of the cooling compressor (114) is selectively connected to reach at least one of the rotatable components. The cooling compressor (114) is connected to rotate at a speed proportional to a rotational speed in one of the main compressor section (102) and the turbine section (108). A valve system (128,130) includes a check valve (130) for selectively blocking flow downstream of the cooling compressor (114) from reaching the at least one rotatable component. A dump valve (128) selectively dumps air downstream of the cooling compressor (114).