Direct-Connect Test of Solid Scramjet with Symmetrical Structure

Pengnian Yang,Yunchao Feng,Zhixun Xia,Binbin Chen,Chaolong Li,Likun Ma,Libei Zhao

doi:10.3390/en14175589

Pengnian Yang, Yunchao Feng + Show 5 more

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https://doi.org/10.3390/en14175589

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Journal: Energies	Publication Date: Sep 6, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: National University of Defense Technology

Abstract

The solid scramjet has become one of the most promising engine types. In this paper, we report the first direct-connect test of a solid scramjet with symmetrical structure, carried out using boron-based fuel-rich solid propellant as fuel. During the test, which simulated a flight environment at Mach 5.6 and 25 km, the performance of the solid scramjet was obtained by measuring the pressure, thrust, and mass flow. The results show that, due to the change in the combustion area of the propellant and the deposition of the throat in the gas generator during the test, the equivalence ratio gradually increased from 0.54 to 0.63. In a solid scramjet, it is possible to obtain a symmetrical distribution of the flow field within the combustor. Moreover, in a multi-cavity combustor, the combustion state expands from the cavity to the center of the flow channel. The performance of the solid scramjet increased during the test, reaching a combustion efficiency of about 42%, a total pressure recovery coefficient of 0.35, and a thrust gain specific impulse of about 418 s. The solid scramjet with symmetrical structure is feasible. The cavity configuration adopted in this paper can reduce the ignition delay time of fuel-rich gas and improve the combustion efficiency of gas-phase combustible components. The shock trains in the isolator are conducive to the recovery of the total pressure. The performance of the solid scramjet is limited by the low combustion efficiency of the particles.

Highlights

Powered hypersonic flight (Ma > 5) is currently a research hotspot in the field of aerospace, with the scramjet being an ideal propulsion equipment for this purpose [1,2,3,4].While most of the current research is based on liquid fuels, the scramjet that employs solid fuel (SSRJ) has many advantages, including simple structure, high energy density, low cost, and safety [5,6,7,8]
Yang et al [29] compared the effects of different injection configurations on performance of SSRJ through a direct connection test, and the results showed that, compared to a round nozzle, an elliptical nozzle is more conducive to the mixed combustion of fuel-rich gas and air
We showed that the cavity layout used in this work had a significant effect on the combustion efficiency of gas-phase combustibles, but it did not have a significant effect on condensed phase particles

Summary

Introduction

Powered hypersonic flight (Ma > 5) is currently a research hotspot in the field of aerospace, with the scramjet being an ideal propulsion equipment for this purpose [1,2,3,4].While most of the current research is based on liquid fuels, the scramjet that employs solid fuel (SSRJ) has many advantages, including simple structure, high energy density, low cost, and safety [5,6,7,8]. In 1989, Witt et al [9] conducted a pioneering experiment of an SSRJ Their test showed that, even though ignition and flame stability are difficult to achieve, solid fuel can burn in a supersonic flow. In 1994, Ben-Yakar et al [11] successfully attained self-ignition and stable combustion of solid propellant without external assistance. A large number of papers based on this configuration show that the cavity can, achieve solid fuel ignition and maintain flame stability. The cavity will gradually disappear as the fuel burns, resulting in a sharp decline in the working performance, preventing the engine to stably operate for extended periods of time [7,8,12,13]

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