Rotorcraft Standby Engine Ice Shedding via Variable Geometry
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Solution Overview
Problem
Operating a multi-engine rotorcraft in cold weather conditions leads to ice accretion on standby engines, causing degraded performance, increased temperatures, and potential engine compressor surges due to asymmetric power operation.
Innovation Solution
A method and system for operating a multi-engine rotorcraft in an asymmetric operating regime, where one engine is active and the other is standby, involves determining conditions for ice accumulation and either increasing the power level or moving variable geometry mechanisms of the standby engine to shed ice, using sensors and control signals to manage fuel flow and vane positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If one engine is operated in standby mode to save fuel during cruising, then fuel efficiency is improved, but ice accretion on the standby engine increases
Solution Approach 1:
The system implements periodic engine cycling where the standby engine is temporarily activated at intervals to prevent ice accumulation. The controller alternates between engines, switching the previously active engine to standby and vice versa, ensuring both engines remain ice-free while maintaining overall fuel efficiency.
Solution Approach 2:
The system changes the operating parameters of the standby engine by temporarily increasing its power output from idle to a higher level. This parameter change creates sufficient airflow and heat to shed ice accumulation, after which the engine returns to standby mode.
2Object-affected harmful factors
If the standby engine power level is increased to shed ice, then ice accretion is reduced, but fuel consumption increases
Solution Approach 1:
Instead of continuously operating both engines at high power, the system uses periodic cycling where each engine is temporarily powered up only when needed to shed ice. This intermittent operation significantly reduces overall fuel consumption compared to continuous high-power operation.
Solution Approach 2:
The system proactively cycles engines before severe ice accumulation occurs by monitoring conditions such as outside air temperature and engine operating hours. This preliminary action prevents ice buildup rather than requiring continuous high-power operation to maintain ice-free conditions.
3Object-affected harmful factors
If variable geometry mechanisms are moved to shed ice, then ice accretion is prevented, but device complexity increases
Solution Approach 1:
The variable geometry mechanisms (inlet guide vanes, variable stator vanes) are controlled to serve dual functions: optimizing engine performance during normal operation and shedding ice when needed. This multi-functionality reduces the need for separate dedicated ice-protection mechanisms.
Solution Approach 2:
The system uses the engine's own existing variable geometry mechanisms to shed ice from its components, rather than requiring external or additional specialized ice-protection equipment. The engine essentially services itself using resources already present in its design.
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 approach effectively prevents ice accumulation on standby engines, maintaining performance and preventing engine issues by periodically or intermittently increasing power and opening variable geometry mechanisms to shed ice, thus ensuring consistent operation in icy conditions.
Implementation Method 1
moving at least one variable geometry mechanism of the at least one second engine to shed any ice accumulation on the at least one second engine
Data Source
AI summary
There is provided a system and a method for operating a multi-engine rotorcraft. When the rotorcraft is cruising in an asymmetric operating regime (AOR) at least one engine is an active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft, at least one of a power level of the at least one second engine is increased and at least one variable geometry mechanism of the at least one second engine is moved to shed any ice accumulation on the at least one second engine.