In the present research, an experimental and numerical investigation has been performed to study initial pressure rise in multi grain solid rocket motor. A cluster of seven uninhibited tubular grains of double base propellant is analysed to get near neutral pressure in rocket motor. It is experimentally observed that in some static firings initial pressure rise in first 100 ms is higher than the predicted value of ∼7.5 MPa. The average pressure in the rocket motor is ∼7 MPa and total burning time of these grains is ∼2 s. ANSYS software is used for numerical analysis to investigate the effects of various % openings of nozzle end (NE) metal grid on pressure rise in the rocket motor with and without peripheral opening. The analysed results are compared with experiments. It is found that, as the %opening of NE metal grid increases, the initial pressure in the rocket motor decreases. The peripheral opening is also important to reduce pressure rise in rocket motor. This study helps in reducing the initial pressure rise in the combustion chamber which is essential for safe working of the rocket motor.

中文翻译：

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多颗粒固体推进剂火箭发动机初始压力上升的研究

在本研究中，已经进行了实验和数值研究以研究多颗粒固体火箭发动机的初始压力升高。分析了七种双基推进剂的不受抑​​制管状颗粒的簇，以在火箭发动机中获得接近中性的压力。实验观察到，在某些静态点火中，最初的100 ms内的初始压力升高高于〜7.5 MPa的预测值。火箭发动机中的平均压力约为7 MPa，这些颗粒的总燃烧时间约为2 s。ANSYS软件用于数值分析，研究在有和没有外围开口的情况下，喷嘴端（NE）金属网格的各种开口百分比对火箭发动机压力升高的影响。将分析结果与实验进行比较。发现，随着NE金属网格的％开口率增加，火箭发动机的初始压力降低。外围开口对于减少火箭发动机的压力升高也很重要。这项研究有助于减少燃烧室中的初始压力升高，这对于火箭发动机的安全运行至关重要。