RAT Actuator Piston Damping for In-Flight Vibratory Loads
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Solution Overview
Problem
Conventional ram air turbine (RAT) systems experience high loads due to low resonance excited by in-flight vibratory loadings, particularly in the windmilling test frequency range, leading to significant cycles at high loads, which existing designs fail to effectively dissipate.
Innovation Solution
The RAT actuator piston incorporates damping holes and a lock rod hole with a larger flow area, along with lock pawl windows and an uplock mechanism, to dissipate vibrational energy and maintain the stowed position, allowing for vibrational damping without hindering deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the RAT actuator is designed with a conventional structure, then the deployment mechanism is simple, but the actuator experiences very high loads due to low resonance excited by in-flight vibratory loadings
Solution Approach 1:
The patent applies a porous damping material within the actuator piston to dissipate vibratory energy. The porous structure allows fluid flow while providing damping capacity, converting the harmful vibratory loads into heat energy through viscous dissipation in the porous medium. This reduces the high loads experienced by the actuator during windmilling operations without requiring a complete redesign of the actuator architecture.
Solution Approach 2:
The patent introduces a damping material as an intermediary element between the piston walls and the fluid. This intermediary absorbs and dissipates the vibratory energy that would otherwise be transmitted to the actuator structure, reducing the harmful effects of resonance while maintaining the overall simplicity of the deployment mechanism.
2Force
If the actuator allows piston movement to dissipate vibratory loads, then the loads are reduced, but the deployment time may increase
Solution Approach 1:
The patent allows for partial piston movement within the damping material during vibratory loading conditions. This partial action is sufficient to dissipate the harmful vibratory energy through the porous medium, while the movement is limited enough to not significantly delay the overall deployment timing. The damping effect occurs during the vibratory cycles without preventing the final deployment position from being reached.
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 design effectively reduces loads on the RAT and actuator, enabling robust, lightweight, and cost-effective systems by dissipating vibrational energy while ensuring fast deployment and eliminating the need for external uplocks.
Implementation Method 1
The one or more damping holes can be configured to allow flow through the damping holes in the locked position to allow the RAT actuator piston to move within the RAT actuator in the locked position to dissipate vibratory loads
Data Source
AI summary
A ram air turbine (RAT) actuator piston can include a body defining a piston structure having an inner cavity. The piston can include one or more damping holes axially defined through the body to the inner cavity and a lock rod hole defined axially through the body to the inner cavity. The lock rod hole can have a larger flow area than one or more of the one or more damping holes. The lock rod hole can be configured to receive a lock rod of a RAT actuator to at least partially block flow through the lock rod hole when the lock rod is in a locked position. The one or more damping holes can be configured to allow flow through the damping holes in the locked position to allow the RAT actuator piston to move within the RAT actuator in the locked position to dissipate vibratory loads.