Effect of Protrusion on Combustion Stability of Hybrid Rocket Motor. Issue 4 (9th March 2022)

• Record Type: Journal Article
• Authors: Dinesh, Mengu; Kumar, Rajiv
• Is Part Of: Propellants, explosives, pyrotechnics. Volume 47:Issue 4(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-09
• Subjects: Hybrid Rocket -- Protrusion -- Combustion Stability -- Wax and Spectrogram; Propellants -- Periodicals; Explosives -- Periodicals; 662.2
• DOI: 10.1002/prep.202100067
• Languages: English
• ISSNs: 0721-3115

Abstract

Abstract: In hybrid rockets, low regression rate and low combustion efficiency are major drawbacks restricting its utilization in practical applications. Inserting a protrusion in a hybrid rocket combustion chamber is one of the methods to enhance the regression rate and combustion efficiency. In the present study, while utilizing the protrusion method the combustion stability of the hybrid rocket was investigated. The protrusions used for this study were of two different types; one was made of graphite and another one was nylon. The nylon protrusion can regress during the combustion along with the fuel whereas, graphite cannot. Before using the protrusion method, the combustion stability of the hybrid rocket motor (base case) was characterized. During the combustion of the base case motor, intense pressure oscillations were observed for a definite period after the beginning of the combustion. These oscillations were found to be the result of the interaction between the vortex shedding and fundamental longitudinal acoustic modes of the chamber at the fuel grain exit. Upon inserting the protrusion near the fuel grain exit, significant suppression in the pressure oscillations was observed. A 96 % reduction in amplitude of acoustic modes relative to the base case was observed. There was no substantial difference in combustion stability of the hybrid rocket when using graphite or nylon protrusions. Further, it was realized that the combustion stability of the rocket motor remains unchanged even after varying the thickness of the protrusion at 0.8X/L location. Abstract :