Flame propagation in swirling flow in a constant–volume chamber with premixed fuel and air has been studied with flame photography and pressure measurement. The entrainment velocity has been calculated by two methods. The first utilizes photographic records to determine flame front propagation rate. From this rate is subtracted the local velocity of the unburned gas (inferred from pressure measurements). The second method utilizes an estimate of the mass entrainment rate inferred from the observed rate of reduction of unburned gas volume, and from pressure measurements. The unsteady velocity signal obtained with a hot wire anemometer has been used with a peak–to–peak counting technique to estimate the micro time and microlength scales of the turbulence and the Taylor rnicrolength scale in the decaying swirling flow in the absence of combustion. Comparison is made with microlength scale calculated using a turbulent entrainment model based on Tennekes turbulence model.