Actuator Cooling Flow Circuit With Pressure-Responsive Bypass Valve
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Solution Overview
Problem
Gas turbine engine actuators face challenges in managing cooling flows due to varying pressure differentials, leading to excess cooling flow and parasitic flow loss, which results in system heating and inefficiency.
Innovation Solution
A cooling flow circuit with a main line, an orifice, a bypass line, and a bypass valve that adjusts its flow area in response to pressure differentials, allowing for reduced orifice size and minimized flow losses by controlling fluid flow through the orifice and a parallel flow limiting valve based on load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cooling flow orifice is sized for the lowest expected pressure differential, then adequate cooling flow is provided at low differentials, but excess cooling flow occurs at higher differentials causing parasitic flow loss and system heating
Solution Approach 1:
The bypass valve dynamically adjusts the cooling flow path based on pressure differential conditions. At low pressure differentials, the bypass valve opens to allow adequate cooling flow through the bypass line. At high pressure differentials, the bypass valve closes to prevent excess cooling flow, thereby eliminating parasitic flow loss and system heating while maintaining reliable cooling when needed.
2Quantity of substance
If a cooling flow orifice is sized for the lowest expected pressure differential, then adequate cooling flow is provided at low differentials, but the orifice must be large causing excess flow at higher differentials
Solution Approach 1:
The cooling flow control is segmented into two parallel paths: a fixed orifice and a bypass line with a controllable bypass valve. The orifice can be optimized for a non-minimal pressure differential without compromising low-differential cooling, while the bypass valve segments the excess flow at high differentials, directing it away from the orifice to maintain system efficiency.
3Reliability
If a larger orifice is used to ensure cooling flow, then cooling is adequate at all pressure differentials, but flow loss increases at higher differentials
Solution Approach 1:
The bypass valve acts as an intermediary that mediates between the orifice and the cooling requirement. It selectively opens or closes based on pressure differential conditions, allowing the orifice to be sized for reliability without always being active. This intermediary control mechanism prevents the orifice from causing excessive flow loss at high differentials while ensuring cooling reliability when pressure differential is low.
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 reduces flow losses, allows for a smaller pump size, and effectively recirculates cooling flows, thereby reducing hydraulic system power requirements and heat removal.
Implementation Method 1
The bypass valve has a variable flow area which is responsive to a pressure differential between the first and second sections... a valve element which is elastically biased to move between open and closed positions relative to the first and second valve openings in response to the pressure differential. springs are provided by which the valve element is anchored to the first and second valve openings and by which the valve element is elastically biased.
Data Source
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AI summary
A cooling flow circuit is provided and includes a main line (23) having first and second sections ported to piston (21) extend and return sides of the gas turbine engine actuator (20), respectively, an orifice (61) disposed along the main line between the first and second sections, a bypass line (62) and a bypass valve (63). The bypass line is fluidly coupled to the first and second sections at opposite ends thereof, respectively. The bypass valve is disposed along the bypass line between the opposite ends thereof. The bypass valve has a variable flow area which is responsive to a pressure differential between the first and second sections.