Turbomachine Ground Test Shroud for Flight Condition Simulation
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Solution Overview
Problem
Ground tests for aeronautical turbomachines on test beds fail to replicate the aerodynamic and acoustic conditions of flight due to static ambient air and differences in stream tube geometry, leading to non-representative testing.
Innovation Solution
A ground testing device featuring a shroud surrounding the engine, creating an annular air flow with a divergent-convergent profile to simulate flight conditions, utilizing aspiration effects to replicate streamline angles and stagnation point positions, without active elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If aerodynamic horns are used to create an artificial corridor guiding air to the engine, then the angle of attack of streamlines approaches real flight conditions, but the equipment does not represent the real geometry of the engine and modifies acoustic conditions
Solution Approach 1:
A shroud is introduced as an intermediary component between the engine and the ambient air. The shroud creates an annular air flow that guides air to the engine inlet while maintaining the engine's original geometry, thus improving both aerodynamic representation and preserving acoustic conditions compared to aerodynamic horns
Solution Approach 2:
The air flow path is segmented into two distinct paths: a main axial flow through the engine core and an annular flow around the engine between the shroud and engine exterior. This segmentation allows independent control of flow characteristics while maintaining geometric fidelity
2Measurement precision
If aerodynamic horns are used to simulate flight conditions, then the stream tube becomes more representative, but the flow is not totally representative and acoustic conditions are modified
Solution Approach 1:
The shroud acts as a mediator that shapes the annular air flow without distorting the engine geometry or internal flow paths, achieving better overall flow representation while preserving acoustic integrity
Solution Approach 2:
The shroud creates a localized annular flow region with specific aerodynamic characteristics around the engine exterior, while leaving the engine's internal geometry and core flow paths unchanged, thus achieving local improvement without global distortion
3Device complexity
If ground tests are conducted without aerodynamic assistance, then the setup is simple and low-cost, but the ambient air is static and does not reproduce the effect of advance
Solution Approach 1:
The shroud utilizes the engine's own operation to generate the annular air flow through pressure differentials created by the downstream shroud presence, eliminating the need for external active elements like fans or blowers, thus maintaining simplicity while achieving representative flow conditions
Solution Approach 2:
The system employs pneumatic principles by utilizing pressure differentials and aspiration effects in the annular air flow to simulate flight conditions, avoiding complex mechanical active elements while achieving the desired aerodynamic environment
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
The device effectively recreates aerodynamic and acoustic conditions of flight, providing a representative and cost-effective testing solution by inducing air flow along the engine's external wall, optimizing flow profiles and stagnation point positions.
Implementation Method 1
the presence of the shroud around the engine therefore allows the creation of a flow of air along the external wall of the engine between its upstream and downstream ends
Implementation Method 2
the air expelled at the nozzle of the engine creates, due to the fact of the downstream presence of the shroud, a reduced pressure at the downstream end of the annular volume between the engine and the shroud
Data Source
AI summary
A ground testing device for a turbomachine, including an aircraft engine (12) extending axially from an air inlet to a nozzle, a shroud (20) having an axis of revolution (A) and surrounding at least partially the engine (12) so as to create an annular air flow between the engine (12) and the shroud (20) when the engine (12) is in operation, and a framework (22) allowing the shroud (20) to be supported.