以數值模擬與實驗方法探討25公斤推力單基火箭引擎搭配氣尖噴嘴之推力表現

Numerical and Experimental Investigation of a 25-kgf Monopropellant Rocket Engine with Aerospike Nozzle

賴建豪(Chien-Hao Lai)

指導教授 ： 吳宗信

國立交通大學/工學院/機械工程系所/碩士(2019年)

摘要

本研究利用數值模擬與實驗探討25公斤推力單基火箭引擎搭配氣尖噴嘴之推力表現，目的在於探討氣尖噴嘴應用於推進器時之推力表現。現今火箭推進系統大多使用第拉瓦噴嘴(de Laval nozzle)，但此設計非常容易受到外界壓力變化而影響推力表現，然而氣尖噴嘴因其特殊的氣針構造，可以自行調整出口氣流狀況，適應外界壓力的變化，相較於第拉瓦噴嘴，能提供更為穩定的推力表現，可適應的飛行高度範圍也更大。第拉瓦噴嘴應用於推力控制引擎時，也會因為燃燒艙壓改變，造成比衝值改變，本研究希望透過氣尖噴嘴的特性來改善此情況，使火箭引擎在進行推力控制時，仍然可以維持穩定的比衝值。
研究中設計了一組用於25公斤推力火箭引擎的第拉瓦噴嘴與氣尖噴嘴進行模擬比較，在相同艙體壓力下，來觀察兩種不同類型噴嘴的經過噴嘴加速的過程的流體變化狀況，以及比較比衝值效率 (〖η_I〗_SP) 。根據模擬結果顯示氣尖噴嘴的比衝值效率優於第拉瓦噴嘴5% ~27%。實驗方面使用單基雙氧水引擎進行噴嘴實際測試，雙氧水供給系統使用氮氣做為加壓氣體，以90 wt %高濃度雙氧水作為推進劑，觸媒則使用二氧化錳作為分解雙氧水之催化劑，根據結果結果顯示氣尖噴嘴的比衝值效率優於第拉瓦噴嘴3% ~ 8%，數值模擬與實驗皆顯示氣尖噴嘴對於艙體壓力改變所造成的推力表現比第拉瓦噴嘴更好。

關鍵字

火箭引擎 ； 單基火箭 ； 氣尖噴嘴

並列摘要

In this study, we would like to investigate the performance of 25-kgf monopropellant rocket engine with aerospike nozzle. The aim of this study is to compare aerospike nozzle with de Laval nozzle applying for the performance of thruster. Nowadays, the de Laval nozzles are widely used for the propulsion system of a rocket. However, the engines with this design do not work as good as expected when the ambient pressure changes with increasing altitude. Instead, the aerospike nozzle can still maintain with high performance when the ambient pressure changes. In a wide range of altitudes, the nozzle can adjust itself because of its special spike structure. The unstable specific impulse also happens when the engines with de Laval nozzle used for throttling. In this case, we suppose the issue can be solved by using aerospike nozzle and make sure the engine still work in high performance.
To compare the differences of propulsion performance, we design two nozzles in the numerical models for a 25-kgf rocket engine. From the numerical result, we can observe how the gas passes through the nozzle with different chamber pressures. By comparing the thrusts generated by the two nozzles, the specific impulse of aerospike nozzle can be up to 5%~27% greater than those of de Laval nozzle. The experimental result shows that the specific impulse of aerospike nozzle can be up to 3%~8% greater than those of de Laval nozzle. Both investigations show that the aerospike nozzle performs better than the de Laval nozzle with the different chamber pressures.

並列關鍵字

rcoket engine ； monopropallent ； aerospike

參考文獻

[1] E.L. Lash, “Trajectory Analysis and Comparison of a Linear Aerospike Nozzle to a Conventional Bell Nozzle for SSTO Flight,” Masters Theses, University of Tennessee, Knoxville, May 2015.

[2] J.H. Ruf and P.K. McConnaughey, “The Plume Physics Behind Aerospike Nozzle Altitude Compensation and Slipstream Effect,” American Institute of Aeronautics and Astronautics (AIAA), Huntsville, AL, 1997.

[3] S.N. Sanoob et al., “Numerical Analysis of Aerospike Nozzle for Spike Length Optimization,” Ineternational Journal of Research in Engineering and Technonlgy (IMPACT), vol. 1, no. 6, pp. 1-14, Kerala, India, 2013.

[4] K. Berman and F.W. Crimp Jr., “Performance of Plug-Type Rocket Exhaust Nozzles,” American Institute of Aeronautics and Astronautics American Rocket Society Journal (ARSJ), vol. 31, no. 1, pp. 18–23, Jan 1961.

[5] T. Tomita et al., “Visualization of Shock Wave Interaction on The Surface of Aerospike Nozzles,” 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 1998.