Details of Grant 

EPSRC Reference:	GR/M63874/01
Title:	ROPA:MULTI-STAGE AEROELASTICITY ANALYSIS OF A COMPLETE TURBOMACHINERY CORE COMPRESSOR
Principal Investigator:	Imregun, Professor M
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	Mechanical Engineering
Organisation:	Imperial College London
Scheme:	ROPA
Starts:	01 May 1999	Ends:	30 November 2001	Value (£):	95,389
EPSRC Research Topic Classifications:	Aerodynamics
EPSRC Industrial Sector Classifications:	No relevance to Underpinning Sectors
Related Grants:
Panel History:
Summary on Grant Application Form
Unsteady turbulent high-speed compressible flows often give rise to complex aeroelasticity phenomena by influencing the dynamic behaviour of structures on which they act. Under certain conditions, the energy transfer from the fluid to the structure can cause excessive vibration levels and structural integrity may be compromised. The problem is particularly severe for aerogas turbines where virtually all bladerows are susceptible to aeroelasticity effects either by inherent self-induced motion (flutter) or by response to aerodynamic flow distortions and blade wakes (forced response). Different aeroelasticity phenomena are associated with different components. For instance, fan blades are known to suffer from flutter and rotating stall. Turbine blades are subjected to aerodynamic excitation containing both high and low harmonics, the former due to wakes from upstream blades and the latter due to the general unsteadiness of the flow, usually caused by a loss of symmetry. The most complex and the least understood aeroelasticity phenomena occur in multi-stage core compressors, the subject of this proposal, because of their wide operating envelope. During engine development programmes, very costly structural failures are known to occur because of a mixture of aeroelastic instabilities such as acoustic resonances, cavity resonances, flutter, high and low engine-order forced response, buffeting, vortex shedding, etc. Most such phenomena are believed to be caused by at least one bladerow undergoing severe stall but the overall compressor still managing to function because of the overall pressure ratio. The numerical modelling of such a situation is a formidable challenge as the analysis must be able to represent accurately not only the aerodynamic and structural properties of a large number of bladerows but also the interactions through these, a route that has never been attempted before. However, as it will be demonstrated in the next section, recent advances in aeroelasticity modelling suggest that most of the required ingredients are now firmly in place for such an investigation. Accordingly, the aim of this proposal is to demonstrate the feasibility of undertaking the aeroelasticity analysis of a core compressor by introducing novel modelling features into an existing computational tool. If the aim can be achieved, a further objective is to explain the blade failure mechanisms for which the current understanding is very poor. The proposed work differs from the current research programme for Rolls-Royce plc because it is too ambitious (and totally untried) to be funded directly by an industrial sponsor. The feasibility of combining a number of key technologies must be demonstrated first. If such a path-finding undertaking proves to be successful, it will pave the way for many more investigations.
Key Findings
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