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Proceedings of the 27th National and 5th International ISHMT-ASTFE Heat and Mass Transfer Conference December 14-17, 2023, IIT Patna, Patna-801106, Bihar, India
December, 14-17, 2023, Bihar, India

Experimental Studies on Pintle Injector in Hybrid Rocket Engine

Get access (open in a dialog) DOI: 10.1615/IHMTC-2023.1010
pages 625-631


The primary aim of the present study is to assess the impact of a pintle injector configuration on the regression rate and combustion efficiency of a hybrid rocket motor (HRM), as compared to a conventional showerhead injector. The pintle injector, characterized by a circular bluff body positioned downstream of the oxidizer supply, is typically employed in liquid rockets to modulate oxidizer delivery and thereby control thrust output. Therefore, it is essential to evaluate the performance of an HRM equipped with this injector and compare it to a conventional showerhead injector, which provides axial oxidizer flow only. In the current study, the propellant combination used consists of Polyvinyl Chloride - Dibutyl phthalate (PVC-DBP) in a 50:50 ratio as the fuel, and Gaseous Oxygen (GOX) as the oxidizer. The initial port diameter of the fuel was set at 35 mm, and the experiments were conducted using the existing setup. The results indicated that the regression rate achieved with the pintle injector was lower when compared to the showerhead injector. However, the combustion efficiency was observed to be superior with the pintle injector. This suggests that the pintle injector enhances the mixing between fuel and oxidizer during combustion. Additionally, the uniformity of the fuel grain after burning was found to be superior with the pintle injector as compared to the showerhead injector.