A TEST DEVICE FOR PREMIXED GAS-TURBINE COMBUSTION OSCILLATIONS

We report the design and operation of a rest device suitable for study ing combustion oscillations produced by commercial-scale gas turbine f uel nozzles. Unlike conventional test stands, this test combustor uses a Helmholtz acoustic geometry to replicate the acoustic response that would otherwise be observed only during complete engine testing. We s uggest that successful simulation of engine oscillations requires that the flame geometry and resonant frequency of the test device should m atch the complete engine environment. Instrumentation for measuring bo th pressure and heat release variation is described. Preliminary tests suggest the importance of characterizing the oscillating behavior in terms of a nozzle reference velocity and inlet air temperature. Initia l tests also demonstrate that the stabilizing effect of a pilot flame depends on the operating conditions.