Engine Rotor Thermal Bow Mitigation via Dynamic Start-Up Control

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Solution Overview

Problem

Conventional start-up techniques for aircraft engines fail to efficiently mitigate thermal bow, leading to unacceptable rub between moving and static parts, which affects engine efficiency and stability during start-up.

Innovation Solution

A start-up assembly comprising sensors and a processor that detect thermal, velocity, vibration, and excursion conditions to calculate a threshold speed for the rotor, allowing it to be accelerated to a predetermined speed before engine start, thereby reducing thermal bow and minimizing rub.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the engine is motored at low speed for an extended time to dissipate thermal bow, then the thermal bow is reduced, but the time required to start the engine significantly increases

Engineering Contradiction:

Improvethermal bowVSAvoidengine start-up time

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

The system performs preliminary action by detecting thermal bow conditions before engine start-up and calculating a specific acceleration profile in advance. The rotor is accelerated according to this pre-calculated profile that optimally dissipates thermal bow, eliminating the need for extended low-speed motoring and reducing start-up time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter of rotor acceleration by using a dynamic acceleration profile instead of constant low-speed motoring. The acceleration rate is adjusted based on detected thermal conditions, allowing the rotor to reach operational speed while dissipating thermal bow efficiently, thus reducing start-up time without compromising thermal bow reduction.

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If the engine is started with thermal bow present, then the start-up time is reduced, but the rub to engine hardware increases to unacceptable levels

Engineering Contradiction:

Improveengine start-up timeVSAvoidrub to engine hardware

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The system uses feedback by continuously detecting thermal conditions and rotor parameters during start-up. Based on this feedback, the controller adjusts the acceleration profile in real-time to ensure thermal bow is adequately dissipated, preventing unacceptable rub to engine hardware while minimizing start-up time.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system applies dynamics by using a dynamic acceleration profile that adapts to real-time thermal conditions. Rather than using a fixed low-speed motoring approach, the rotor acceleration is dynamically adjusted based on detected thermal bow, allowing optimal balance between reducing rub and minimizing start-up time.

Inventive Principle:

Principle #15Dynamics

3Productivity

If conventional start-up techniques are used, then the engine can be started quickly, but the gap between moving and static parts deteriorates due to thermal bow

Engineering Contradiction:

Improvestart-up speedVSAvoidgap between moving and static parts

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system replaces the conventional mechanical approach of fixed-speed motoring with an intelligent control system that uses sensors and algorithms. This substitution allows the system to calculate and execute an optimized acceleration profile that maintains proper gaps between moving and static parts while enabling quick start-up.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs preliminary detection of thermal conditions and pre-calculates the optimal acceleration profile before start-up. This preliminary action ensures that the rotor is accelerated in a manner that maintains proper clearance between moving and static parts, preventing gap deterioration while enabling rapid start-up.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3660280B1Apparatus, assemblies, and methods for mitigating thermal bow in the rotor of an engine at start-up

Publication Date: 2023.01.04 THE BOEING CO

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AI summary

Disclosed herein are apparatus, assemblies, and methods for mitigating thermal bow in the rotor (75) of an engine (50) at start-up. One apparatus includes a control module (602) that facilitates operating the rotor (75) prior to starting the engine (50) and an acceleration module (604) that facilitates accelerating the rotor (75) to at least a threshold speed prior to starting the engine (50). An assembly includes a start-up device (204) coupleable to the rotor (75) and configured to start the rotor (75) and a start-up module (502) coupled to the start-up device (204) in which the start-up device (204) and the start-up module (502) are configured to coordinate operations to accelerate the rotor (75) to at least a threshold speed prior to starting the aircraft engine (50). One method includes transmitting a control signal to control the rotor (75) prior to starting the engine (50) and commanding the start-up device (204) to accelerate the rotor (75) to at least a threshold speed prior to starting the engine (50).