The influence of injector design on the decay of pre-ignition turbulence in a spherical explosion chamber

This paper reports on an experimental study to characterize the turbulent R ow field inside a 20 1 Siwek chamber during the pre ignition period. An acr ylonitrile-butadiene-styrene model of the chamber was constructed with opti cal quality windows enabling laser Doppler anemometry (LDA) to be used for turbulence measurements. Alumina (Al2O3) particles were used as the seed du st for measuring the gas-phase turbulence. Three specific dust dispersion s ystems have been investigated: (1) the deflector plate (also referred to as the rebound nozzle); (2) the perforated annular nozzle; and (3) the circul ar "Dahoe" nozzle. It is assumed that changing the method of dust dispersio n alters the turbulence characteristics. The flow field is non-stationary, i.e., the mean (or predominant fluid flow) and superimposed velocity fluctu ations upon the mean decrease with time. Furthermore, there are variations from injection to injection. A procedure has been developed to analyze this non-stationary signal to extract the mean and fluctuating components of ve locity, thereby paving the way for decay "laws" to be determined for a part icular nozzle configuration. (C) 2001 Elsevier Science Ltd. All rights rese rved.