Combustion and Turbulent Structure in a Closed Chamber with Swirl

Measurement of combustion duration and turbulence in a swirling flow have been carried out in a centrally-ignited cylindrical bomb which was charged by rapid tangential injection of premixed near-stoichiometric propane and air. Pressure rise versus time was measured using a pressure transducer. Turbulence intensity and mean flow were estimated by statistical analysis of a single hot wire anenometer signal. Probability distribution functions of the micro-lime scale were deduced from The hot wire signal using a peak-to-peak counting technique. Results indicate that combustion duration decreases substantially with increasing swirl and turbulence intensity. The initiation period (zero to 10 percent pressure rise) was approximately double the main combustion period (10-100 percent pressure rise). Hot wire analysis showed that the turbulence tends to homogeneity and that the ratio of turbulence intensity to mean velocity approaches a constant value as the turbulence decays. The integral length scale, deduced from the rate of decay of The turbulence, is approximately equal to the distance between the end plates of the disc-shaped chamber. The most probable micro-time scale remains a constant at the outer edge of the flow and increases in the central region as the flow decays. The microlength scale, (calculated from measured rnicrolime scale using The Taylor hypothesis) in the outer region of the flow decreases as the flow decays.