Gas Turbine Cooling Valve Modulation for Pressure Margin
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Solution Overview
Problem
Upgrading gas turbine engines often results in increased air pressure in the turbine section, leading to insufficient cooling flow due to reduced pressure margin between the compressor and turbine sections, particularly on cold days, where existing cooling systems fail to maintain adequate cooling of components.
Innovation Solution
The implementation of a cooling flow circuit with a full capacity valve in the turbine cooling air supply main line, replacing the small capacity valve and orifice, and an additional cooling network that switches between compressor and combustor sources to maintain target pressure ratios and prevent overflow, allowing operation across a wider ambient temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a gas turbine engine is upgraded to increase air pressure in the turbine section, then power output and efficiency are improved, but the pressure margin between compressor and turbine sections is reduced, resulting in insufficient cooling flow to turbine components
Solution Approach 1:
The patent replaces fixed restriction elements (orifice, small capacity valve) with a dynamically controllable full capacity valve that can adjust its opening degree based on real-time pressure measurements. This dynamic adjustment allows the system to maintain adequate cooling flow despite variations in turbine section pressure caused by engine upgrades or environmental conditions.
Solution Approach 2:
The system implements a feedback control mechanism where pressure sensors continuously monitor the pressure in the blade ring cavity and compressor cavity, and the control system adjusts the full capacity valve opening degree accordingly to maintain the target pressure ratio. This closed-loop feedback ensures reliable cooling flow under varying operating conditions.
2Loss of energy
If the cooling air supply main line uses a small capacity valve or orifice to control cooling flow, then pressure losses are reduced under normal conditions, but the system cannot maintain adequate cooling flow when pressure margin is reduced or ambient temperature is extremely low
Solution Approach 1:
The full capacity valve provides dynamic flow control capability that fixed orifices and small capacity valves lack. By adjusting the valve opening degree, the system can optimize the balance between pressure loss and cooling flow adequacy across different operating conditions, including extreme cold temperatures and reduced pressure margin scenarios.
Solution Approach 2:
The system changes the flow control parameter from a fixed restriction (orifice/small valve) to a variable restriction (full capacity valve with adjustable opening degree). This parameter change enables the system to adapt to varying pressure conditions and maintain adequate cooling flow where fixed restrictions would fail.
3Reliability
If the full capacity valve opening degree is increased to maintain cooling flow under low pressure margin conditions, then cooling flow adequacy is improved, but pressure losses in the cooling flow circuit increase
Solution Approach 1:
The full capacity valve dynamically adjusts its opening degree to find the optimal balance between cooling flow adequacy and pressure loss. Under normal conditions, the valve maintains a smaller opening to minimize pressure losses, while under low pressure margin or extreme cold conditions, it increases the opening to ensure adequate cooling flow.
Solution Approach 2:
The system uses parameter changes in the valve opening degree to adapt to different operating conditions. The control system monitors pressure conditions and adjusts the valve opening parameter to maintain the target pressure ratio, thereby balancing cooling effectiveness with pressure loss minimization.
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 ensures sufficient cooling of turbine components across varying ambient temperatures, including extreme cold conditions, by reducing pressure losses and utilizing high-pressure combustor air when necessary, thus extending the engine's operational range without performance loss.
Implementation Method 1
measuring a first pressure in the blade ring cavity, measuring a second pressure in the combustor shell cavity, adjusting, by a control system in the gas turbine engine, the opening of the full capacity valve to control the cooling air flow through the cooling air main line in order to maintain a target pressure ratio
Data Source
AI summary
A method of modulating a cooling supply in a gas turbine engine includes providing the engine comprising a compressor section and a turbine section and including a cooling flow circuit, the cooling flow circuit supplying a cooling air flow from a compressor cavity in the compressor section to a blade ring cavity in the turbine section, wherein the cooling flow circuit includes a main line with a full capacity valve, measuring a first pressure in the blade ring cavity, measuring a second pressure in the compressor cavity, adjusting, by a control system, the opening of the full capacity valve to control the cooling air flow through the main line in order to maintain a target pressure ratio, wherein the pressure ratio defined as a ratio of the first pressure to the second pressure. The method is performed in an ambient temperature operating range of the engine.