Auxiliary Hydraulic Power Generation System for Aircraft Emergency Control
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Solution Overview
Problem
Modern gas turbine engines lack an efficient emergency power source for controlling flight surfaces in case of primary power loss, with existing solutions like aircraft batteries for small planes and ram air turbines for larger ones being inadequate or cumbersome.
Innovation Solution
An auxiliary hydraulic power generation system that utilizes a windmill condition of a gas turbine engine's low spool to drive an auxiliary variable displacement hydraulic pump through a speed-up gearbox, providing pressurized fluid to the aircraft hydraulic system, thereby augmenting the hydraulic power source and reducing the need for additional emergency power systems like the ram air turbine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ram air turbine is provided for emergency power, then hydraulic power availability is improved, but device complexity and weight increase
Solution Approach 1:
The low spool serves multiple functions: during normal operation it drives the fan and compressor, and during emergency conditions it winds mills to drive the hydraulic pump through the gearbox and coupling. This multi-functionality eliminates the need for a separate ram air turbine system.
Solution Approach 2:
The emergency power generation function is merged with the existing low spool assembly by integrating the gearbox and hydraulic pump into the engine structure, rather than adding a separate external emergency power system.
2Reliability
If a ram air turbine is provided for emergency power, then hydraulic power availability is improved, but weight increases
Solution Approach 1:
The low spool serves multiple functions: during normal operation it drives the fan and compressor, and during emergency conditions it winds mills to drive the hydraulic pump through the gearbox and coupling. This multi-functionality eliminates the need for a separate ram air turbine system.
Solution Approach 2:
The emergency power generation function is merged with the existing low spool assembly by integrating the gearbox and hydraulic pump into the engine structure, rather than adding a separate external emergency power system.
3Reliability
If the auxiliary hydraulic pump is driven by the low spool in windmill condition, then hydraulic power is augmented, but power consumption from the engine increases
Solution Approach 1:
The coupling between the low spool and hydraulic pump is designed to engage only under specific dynamic conditions (windmill operation at elevated speeds), allowing the system to automatically activate when needed without continuous power consumption during normal operation.
Solution Approach 2:
During emergency conditions, the low spool automatically winds mills and drives the hydraulic pump without requiring external power input or active control, utilizing the available airflow to generate the necessary hydraulic power.
4Power
If a speed up gearbox is used between the low spool and hydraulic pump, then hydraulic power output is improved, but device complexity increases
Solution Approach 1:
The speed up gearbox acts as an intermediary device that bridges the low spool and hydraulic pump, enabling efficient power transmission by matching the speed and torque requirements of the pump while simplifying the connection to the low spool.
Data Source
Figure 1
Figure 2
AI summary
An auxiliary hydraulic power generation system (40) includes a first spool (14) including a turbine (18). A fan (20) is coupled to the first spool (14), the fan being operable to drive the first spool in a windmill condition in which the turbine fails to provide rotational drive to the fan. An auxiliary variable displacement hydraulic pump (48) is selectively driven by the first spool (14) in the windmill condition to augment a hydraulic power source.