This paper reports on the internal flow of a centrifugal mini pump. The RNG k-epsilon turbulence model was employed to simulate the three-dimensional turbulent flow in the pump. To examine and certify the simulation results, a transparent acrylic centrifugal mini pump model which is suitable for PIV measurement has been developed. The tongue region and the passages region between blades were investigated using PIV. In order to eliminate the effect of refraction on the area close to the wall and increase the measurement accuracy, the fluorescent particles were scatted into the working fluid with the tracing particles. It is found from the calculation and PIV measurement results that there is a large area of recirculation flow near the tongue at low flow rate working conditions. The computationally predicted water head using the RNG k-epsilon turbulence model are in very good agreement with the experimentally measured water head and the mean velocity distributions at investigation area obtained by PIV and calculation showed a satisfactory agreement as well. Meanwhile, the results of PIV measurements show that the flow status in one passage is different to another. And for capturing the internal flow detail information, the RNG k-epsilon turbulence model is not very suitable.

In this study, a new approach for predicting flame spread along a combustible solid is developed. This presented approach consists of a two-dimensional flame spread model coupled with a one-dimensional pyrolysis model in the thickness direction. The flame spread model is based on a cellular automaton combined with piloted ignition temperature, spontaneous ignition temperature, and pyrolysis temperature of a combustible solid. In addition, this approach is used to predict two typical kinds of flame spread, i.e., upward flame spread and ceiling flame spread. The existing experimental data including the upward flame spread over plywood and the ceiling flame spread beneath medium density fiberboard (MDF) are used for comparison to validate this approach. The results obtained from numerical simulations using this approach are consistent with these two kinds of experimental tests.