Variable Oil Flow Restrictor for Heat Exchanger Pressure Control
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Solution Overview
Problem
Aircraft heat exchangers face challenges in maintaining optimal oil pressure within desired operating ranges, especially when using lighter and more efficient variants, which can lead to impaired component operation and increased complexity in redesigning downstream components.
Innovation Solution
Incorporating a flow restrictor with a variable orifice size, controlled by an actuator and sensor feedback, to maintain oil pressure within desired ranges by adjusting the orifice size based on pressure and temperature signals, thereby optimizing performance across different operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If lighter and more efficient heat exchanger variants are used, then weight and efficiency are improved, but oil pressure control becomes difficult and component operation may be impaired
Solution Approach 1:
A flow restrictor is introduced as an intermediary device between the heat exchanger and the component to regulate oil pressure. The flow restrictor compensates for the reduced pressure differential caused by lighter heat exchangers, ensuring that components receive adequate oil pressure without requiring redesign of the heat exchanger or component.
2Weight of moving object
If lighter heat exchangers are used, then weight is reduced, but redesign of components becomes complex and costly
Solution Approach 1:
The flow restrictor serves as a simple intermediary component that enables the use of lighter heat exchangers without requiring complex redesigns of existing components. By inserting the flow restrictor in the oil conduit, the system maintains compatibility with original components while achieving weight reduction.
Solution Approach 2:
The flow restrictor changes the pressure differential parameter in the oil system by providing an additional pressure drop. This parameter adjustment allows lighter heat exchangers to maintain adequate oil pressure at components without altering the heat exchanger design or component specifications.
3Device complexity
If flow restrictor size is fixed, then device complexity is reduced, but adaptability to varying operating conditions is limited
Solution Approach 1:
The flow restrictor incorporates a movable member that can dynamically adjust the orifice size in response to changing operating conditions. This dynamic adjustment capability allows the system to adapt to varying oil pressure requirements while maintaining relatively simple device architecture through the use of a straightforward actuation mechanism.
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 flow restrictor system ensures consistent oil pressure, reducing the need for component redesign and maintaining efficient lubrication, while accommodating various heat exchanger configurations without increasing costs or complexity.
Implementation Method 1
flowing the oil flow through the flow restrictor having an orifice sized to create a restrictor pressure differential
Implementation Method 2
a first heat exchanger providing heat exchange between the oil flow and an air flow
Implementation Method 3
a second heat exchanger providing heat exchange between the oil flow and a fuel flow
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An oil system (28), has: a pump (32) driving an oil flow (F1) in an oil conduit (33), the pump (32) having an outlet pump pressure; a heat exchanger (41, 42) providing heat exchange between the oil flow (F1) and one or more fluid; a component downstream of the heat exchanger (41, 42), the component having a maximum oil pressure requirement and a minimum oil pressure requirement; and a flow restrictor (37) in fluid flow communication with the oil conduit (33), the flow restrictor (37) having an orifice (37A) sized to provide a restrictor pressure differential across the flow restrictor (37), the restrictor pressure differential being equal to at least the outlet pump pressure minus pressure differentials through the heat exchanger (41, 42) and the oil conduit (33) from an outlet of the pump (32) to the component minus the maximum oil pressure requirement, and at most the outlet pump pressure minus the pressure differentials through the heat exchanger (41, 42) and the oil conduit (33) minus the minimum oil pressure requirement.