Ram Air Turbine Damping Orifice Thermal Expansion
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Solution Overview
Problem
Ram air turbine (RAT) actuators face challenges in maintaining consistent deployment times and impact forces across varying temperatures due to the temperature-dependent viscosity of hydraulic fluids, which can result in either excessive deployment time or impact forces exceeding structural capabilities.
Innovation Solution
The design incorporates a damping orifice blocking device made of a material with a higher thermal expansion coefficient than the piston, allowing or blocking fluid flow through damping orifices based on temperature ranges to adjust the damping effect, ensuring consistent deployment across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If damping orifices are designed to provide sufficient damping at high temperatures, then impact forces are reduced, but deployment time increases excessively at low temperatures
Solution Approach 1:
The damping orifice flow area is made dynamically adjustable through a blocking device that responds to temperature changes. The blocking device transitions between open and closed states based on temperature, automatically adjusting the damping characteristics to match operating conditions without manual intervention or complex control systems.
Solution Approach 2:
The system changes the physical parameter of flow area in response to temperature variations. At low temperatures, the full flow area is open for rapid deployment; at high temperatures, the flow area is reduced to limit impact forces. This parameter change is achieved through thermal expansion of the blocking device material.
2Loss of time
If damping orifices are designed for rapid deployment at low temperatures, then deployment time is reduced, but impact forces exceed structural capabilities at high temperatures
Solution Approach 1:
The blocking device is made from a material with a high coefficient of thermal expansion that exceeds the expansion rate of the piston. As temperature increases, the blocking device expands and blocks the damping orifices, automatically reducing the flow area to limit impact forces at high temperatures while maintaining full flow area for rapid deployment at low temperatures.
Solution Approach 2:
The blocking device acts as an intermediary element between the piston and the damping orifices. It mediates the fluid flow based on temperature conditions, expanding to block orifices when hot and retracting to open them when cold, thereby protecting the system from excessive impact forces without compromising deployment speed.
3Device complexity
If a single damping orifice design is used, then device complexity is reduced, but the system cannot adapt to temperature variations
Solution Approach 1:
The blocking device is a passive, self-actuating component that automatically adjusts the damping orifice flow area in response to temperature changes. It requires no external power, control signals, or complex mechanisms - simply the thermal expansion properties of its material enable it to perform the adaptation function autonomously.
Solution Approach 2:
The blocking device utilizes the thermal expansion properties of its material to automatically adjust the damping characteristics. The material is selected to have a coefficient of thermal expansion greater than the piston material, ensuring reliable blocking action at high temperatures while maintaining simplicity in design and operation.
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 allows for controlled damping adjustments with temperature, maintaining consistent deployment times and reducing impact forces, thereby enhancing the structural integrity and efficiency of RAT actuators.
Implementation Method 1
The second material of the damping orifice blocking device can thermally expand faster than the first material of the piston
Data Source
AI summary
A ram air turbine (RAT) actuator includes a housing and a piston in operable communication with the housing and at least one damping orifice in operable communication with the housing and the piston, a flow area of the at least one damping orifice being alterable to adjust damping of movement between the piston and the housing in response to changes in viscosity of a fluid related to temperature.