Since the accumulator is one of main contributors to the overall noise level of the rotary compressor, research on the acoustic performance of accumulators is essential. Numerical analysis based on the computational fluid dynamic method shows that large pressure fluctuations are caused mainly by periodic rotating piston. The idea that the flow phase differences of two pipes could be utilized for suppressing fluctuations is proposed. The double standpipes of an accumulator are changed to the single pipe with two branches and each branch is connected to the inlet of the compressor. Flow structures and wall pressure fluctuations for the two configurations are computed. Computational results show that wall pressure pulsations of the new accumulator are obviously lower than that of the original. The acoustic experiments were carried out under the real working conditions. Compared with the original, the new accumulator shows that the overall noise level is reduced about 1.2 dB(A) and the sound spectrum levels are also lower in a wide frequency domain, which validate the numerical and theoretical analysis.
In order to explore the flow field characteristics of nozzle plume for a small solid rocket motor (SRM), the two-dimensional axisymmetric N-S governing equations with component transports and chemical reaction terms are established. Then, the finite volume method of AUSM (Advection Upstream Splitting Method) spatial discretization scheme is applied for numerical discretization, and its solution is solved by time iteration to make the plume flow field steady. This technique is applied to research the flow field characteristics and characteristic parameter distributions of nozzle plume under different inflow conditions. The results are shown that: when considering the reburning reactions of nozzle plume, the temperature of the gas jet core area is much higher than the flow field temperature that the reburning phenomenon is not considered. In addition, the reburning phenomenon mainly occurs in the air-gas mixing and gas development areas, but in the initial core area of gas jet, this phenomenon is not obvious. What’s more, with the increase of altitude, the influence area of the gas jet gradually becomes larger. However, as the incoming flow Mach number increases, the intensity of the change of gas temperature along the nozzle axis weakens, and also the number of wave nodes and the influence region of gas jet gradually decrease.
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