Abstract An attempt has been made in the present study to realize the effect of multi-location swirl injection on the improvement of regression rate and combustion efficiency of hybrid rocket by using two different length to diameter (L/D) ratio of the motor. It is 12 and 24. The fuel used for the study was Polyvinyl chloride (PVC)-Dibutyl Phthalate (DBP) in the ratio of 50:50. The gaseous oxygen was used as the oxidizer. The significance of this method is that a single swirl injection at the head end of the hybrid rocket is not sufficient to provide swirling flow till the nozzle end, if the length of the motor is sufficiently long and the regression rate decreases beyond certain length. In the present study, it has been observed that the 220 mm length is sufficient to get the improvement with single swirling injection. For the 24 L/D motor, the use of multi-location swirl injector motor gave twice the improvement in regression rate compare to the conventional hybrid rocket motor where showerhead injector has been used. Combustion efficiency obtained with multi-location swirl injection gave lower improvement with 24 L/D motor (from 70% to 76%), but the improvement was significant with 12 L/D motor with single swirl injector (from 50% to 74%). Improvement in regression rate as well as the efficiency was observed to be significant, if the mid injector was used as the cavity instead of supplying oxygen through it. The value of mass flux exponent (n) was observed to be 0.51 with multi-location swirl injection and the relatively uniform regression rate from head end to the nozzle end was observed.

中文翻译：

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多位涡流喷射对混合火箭发动机性能的影响

摘要 本研究尝试利用两种不同的长径比(L/D)来实现多位置涡流喷射对提高混合火箭回退率和燃烧效率的影响。它是 12 和 24。用于研究的燃料是比例为 50:50 的聚氯乙烯 (PVC)-邻苯二甲酸二丁酯 (DBP)。气态氧用作氧化剂。这种方法的意义在于，如果发动机的长度足够长并且回归率降低超过一定长度，则混合火箭头端的单次旋流喷射不足以提供直到喷嘴端的旋流。在本研究中，已经观察到 220 mm 的长度足以通过单次涡流注射获得改进。对于 24 L/D 电机，与使用喷头喷射器的传统混合火箭发动机相比，使用多位置旋流喷射器马达使回归率提高了两倍。多位置旋流喷射获得的燃烧效率在使用 24 L/D 电机时的改进较低（从 70% 到 76%），但使用带有单旋流喷射器的 12 L/D 电机的改进显着（从 50% 到 74%） . 如果将中间注射器用作腔而不是通过它供应氧气，则观察到回归率和效率的改善是显着的。观察到质量通量指数 (n) 的值为 0.51，采用多位置涡流喷射，观察到从头端到喷嘴端的回归率相对均匀。