Fixed Flow Cooling Compressor for Variable Geometry Turbine
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Solution Overview
Problem
In gas turbine engines, the introduction of cooling air to the turbine section becomes excessive when the variable vane is actuated to a closed position, leading to undesirable pressure changes and flow resistance issues, which existing technologies struggle to manage effectively.
Innovation Solution
The implementation of a fixed flow cooling compressor, such as a positive displacement pump or vane pump, which taps air from an upstream location in the compressor section and passes it through a heat exchanger before compression, ensures consistent air flow to the turbine section, even as pressures change, using a bull gear and accessory gearbox to optimize compression and delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is supplied from the compressor section to the turbine section, then the turbine section temperature is reduced and cooling effect is improved, but when the variable vane is actuated to a closed position, excessive cooling air enters the turbine section causing pressure changes and flow resistance issues
Solution Approach 1:
The patent applies a variable geometry turbine with movable vanes that can dynamically adjust the flow area and pressure distribution within the turbine section. This dynamic adjustment allows the system to maintain optimal pressure conditions while permitting adequate cooling air flow, resolving the contradiction between cooling effectiveness and pressure stability during variable vane actuation.
Solution Approach 2:
The patent introduces an intermediary cooling air supply system that includes a cooling air compressor and control mechanism positioned between the compressor section and turbine section. This intermediary system regulates the cooling air flow independently, ensuring that cooling requirements are met without causing excessive pressure changes or flow resistance issues in the main gas path.
2Adaptability or versatility
If the variable vane is moved to a more closed position to control combustion products flow, then the expansion ratio across the turbine section increases and downstream pressure decreases, but this lowers resistance to cooling air entry causing excessive cooling air flow
Solution Approach 1:
The patent implements a feedback control system that monitors the actual cooling air flow and pressure conditions in the turbine section. Based on this feedback, the control mechanism adjusts the variable vane position and cooling air supply to maintain the desired cooling air volume, preventing excessive flow even when the variable vane is actuated to closed positions for flow condition control.
Solution Approach 2:
The patent changes the parameters of the cooling air supply system by introducing a dedicated cooling air compressor and control mechanism that can independently regulate cooling air flow rate and pressure. This parameter control allows the system to maintain adaptability in flow condition control while preventing excessive cooling air volume entry during variable vane actuation.
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 maintains consistent cooling air flow to the turbine section, reducing the risk of excessive air entry and improving operational efficiency by compressing air to higher pressures at lower temperatures, thus addressing the pressure and flow resistance challenges posed by variable vane actuation.
Implementation Method 1
passes it through a heat exchanger before compression
Implementation Method 2
The implementation of a fixed flow cooling compressor, such as a positive displacement pump or vane pump
Data Source
Figure 1
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Figure 4
AI summary
A gas turbine engine (20; 100) has a main compressor section (24). A turbine section (28) has a variable vane (144) positioned upstream of a rotor blade (142), and the variable vane (144) is provided with an actuator (146) operable to control an orientation of the variable vane (144). A tap line (110) taps air from the compressor section (24), and passes the tapped air through a cooling compressor (148). The cooling compressor (148) is a fixed flow compressor. Air downstream of the cooling compressor (148) is delivered into the turbine section (28).