Details of Grant 

EPSRC Reference:	GR/L88276/01
Title:	OSCILLATIONS IN AEROENGINE COMBUSTION CHAMBERS
Principal Investigator:	Dowling, Professor Dame A
Other Investigators:	Bray, Professor K
Researcher Co-Investigators:
Project Partners:	Ministry of Defence (MOD) Rolls-Royce Plc (UK)
Department:	Engineering
Organisation:	University of Cambridge
Scheme:	Standard Research (Pre-FEC)
Starts:	13 January 1998	Ends:	12 January 2000	Value (£):	74,402
EPSRC Research Topic Classifications:	Combustion
EPSRC Industrial Sector Classifications:	Aerospace, Defence and Marine
Related Grants:
Panel History:
Summary on Grant Application Form
The drive for low emissions from aeroengines has led to combustion chambers being increasingly susceptible to low frequency oscillations. The associated pressure fluctuations are generally disturbing, and can be so intense that they stall the engine. These self-excited oscillations involve coupling between fuel-spray atomisers, unsteady conbustion and pressure waves. Essentially, pressure and velocity fluctuations at the atomiser alter the fuel and air input thereby changing the rate of combustion. The resulting unsteady conbustion can feed energy into the flow perturbations. If this energy gain exceeds that lost across the boundaries of the combustion chamber, linear waves grow in amplitude and the flow is unstable. We will use numerical computations to determine the unsteady combusting flow driven by imposed variations in the fuel and air supplies. The time evolution of self-excited oscillations follows once this is combined with simple models of the air and fuel supply systems. Particular emphasis will be placed on determining the most important feedback mechanism and on developing a physical model of this instability.This project will lead to an improved understanding of oscillations with fuel-spray atomisers, and will help in the design of aeroengines which can run quietly and safely with low emmisions.
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Organisation Website:	http://www.cam.ac.uk