Numerical and experimental investigation on hybrid rocket motor with two-hole segmented rotation grain

This paper investigates the effect of rotation angles on the fuel regression rate and the motor combustion efficiency in hybrid rocket motor with two-hole segmented grains. In this research, the propellant combination of 90% hydrogen peroxide (H2O2) and polyethylene (PE) is adopted, and two two-hole grains with the same configuration are used to conduct both numerical and experimental tests. A 3D simulation model is established to obtain combustion efficiency, fuel regression rate, temperature distribution and species mass fraction distribution. Meanwhile, in order to achieve the motor combustion efficiency and the average regression rate, 20 firing tests were conducted on a lab-scale hybrid rocket motor. The numerical and experimental results agree well and demonstrate that the rotation of after-section grain has no influence on the fore-section grain regression rate, while the after-section grain regression rate arises, compared with the no rotation case. Regression rates are fitted with the following empirical equation, (r) over dot = aG(ox)(n) (1 - e(-(D) over bar pm)), in which the regression rate coefficients a and n of after-section grain changed with the rotation angle. The motor combustion efficiency is higher than the base operation condition. It increases gradually with the increase of rotation angle, and the increasing rate becomes slower. The combustion efficiency can reach to the maximum when the rotation angle is 45 degrees, after which it drops slowly, and the rate of descent is slower than that of ascent. (C) 2019 Elsevier Masson SAS. All rights reserved.