Turbine Engine Fluid Circuit With Laminar Restrictor Bypass Control
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Solution Overview
Problem
Existing solutions for controlling the flow of fluid through heat exchangers in turbomachines are either mass and size penalizing, unreliable, or unable to completely stop fluid circulation, leading to inefficient cooling and potential oil retention issues.
Innovation Solution
A device featuring a slide valve controlled by a laminar flow restriction, where the pressure drop across the restriction determines the valve's position, allowing complete stoppage of fluid circulation and reliable bypass control, independent of hydraulic pressure drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a shut-off valve with actuator and electrical control circuit is used to control airflow through the oil-to-air heat exchanger, then the oil temperature can be controlled, but the weight and bulk of the turbomachine increases significantly
Solution Approach 1:
The patent employs a thermostatic valve containing wax that automatically responds to oil temperature changes. When the oil temperature rises, the wax melts and causes the valve to close; when the temperature falls, the wax re-solidifies and the valve opens. This self-regulating mechanism eliminates the need for external actuators and electrical control circuits, thereby avoiding the weight and bulk penalties associated with those components.
Solution Approach 2:
The thermostatic valve utilizes the phase transition of wax between solid and liquid states in response to temperature changes. This phase transition directly actuates the valve opening and closing, providing a simple, weight-efficient temperature control mechanism that does not require additional power systems or control electronics.
2Temperature
If a shut-off valve is installed in the secondary air stream to control airflow through the oil-to-air heat exchanger, then the oil temperature can be controlled, but the pressure drop increases significantly, increasing fuel consumption
Solution Approach 1:
The thermostatic valve automatically regulates airflow based on oil temperature without requiring external control systems. This eliminates the need for high-pressure shut-off valves in the secondary air stream, maintaining proper airflow and pressure characteristics while still achieving effective temperature control.
Solution Approach 2:
By using wax phase transition to control a bypass valve rather than directly controlling the main air stream, the system avoids creating significant pressure drops. The valve directs oil flow through bypass paths when closed, maintaining airflow continuity and minimizing energy losses in the secondary air stream.
3Reliability
If a thermostatic valve with wax is used in a bypass line to control oil flow, then the valve can withstand many opening/closing cycles, but the oil flow cannot be completely stopped, leading to continuous cooling and potential oil retention issues
Solution Approach 1:
Instead of using a bypass valve that allows partial flow, the patent inverts the approach by using a main line shut-off valve that completely stops oil flow when closed. The thermostatic valve is positioned to control the primary oil path, ensuring complete flow cessation when needed, while the bypass provides an alternative path only when the main valve is open.
Solution Approach 2:
The oil control system is segmented into two independent pathways: a main line controlled by a thermostatic shut-off valve for complete flow control, and a bypass line that provides alternative flow when the main valve is open. This segmentation allows the main valve to achieve complete flow stoppage while the bypass ensures continuous oil circulation when heating is required.
4Temperature
If the thermostatic valve opening/closing threshold temperature is increased to prevent oil cooling below threshold, then oil retention is prevented, but the number of opening/closing cycles increases, reducing valve reliability
Solution Approach 1:
The thermostatic valve utilizes the phase transition of wax, which provides a natural hysteresis effect. The wax melts at a specific temperature and re-solidifies at a slightly lower temperature, creating a temperature differential that prevents frequent cycling. This phase transition mechanism naturally limits the number of opening/closing cycles while maintaining oil temperature within acceptable ranges.
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
Enables complete stoppage of fluid circulation in cold conditions, preventing cooling and ensuring reliable oil temperature maintenance, while reducing the number of valve cycles and avoiding unstable operation.
Implementation Method 1
it includes means for moving the spool of the fluid distributor between its two positions by the pressure drop of the fluid in the laminar flow restriction
Implementation Method 2
a laminar flow restriction is arranged in the fluid circuit upstream of the distributor
Implementation Method 3
the oil being cooled by heat exchange with the fuel
Data Source
Figure 1~2
Figure 3
AI summary
The invention concerns a device for controlling the fluid supply of a piece of equipment (48), such as a heat exchanger, comprising a fluid distributor (46) mounted in a fluid circuit and comprising a spool (52) that can be moved between two positions, in the first of which it allows the flow of fluid into the piece of equipment (48) and in the second of which it prevents the flow of fluid into the piece of equipment (48). The device also comprises a laminar flow restrictor (44) arranged in the fluid circuit upstream from the distributor (46) and means for moving the spool of the fluid distributor between the two positions of same by means of the loss in fluid pressure in the laminar flow restrictor (44).