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Received 13 May 2016; received in revised form 16 September 2016; accepted 19 December 2016
KEYWORDS
Hybrid motor;
Regression rate;
Oxidizer;
Fuel;
Pressure.
Abstract. The performance of an HTPB/N2O hybrid motor was experimentally investigated. A hybrid motor was designed and manufactured in a laboratory with the purpose of studying the effects of various parameters on the motor's performance, including fuel regression rate and specific impulse. A series of tests were conducted to find a correlation between the fuel regression rate and the oxidizer's mass flux. The effects of chamber's pressure on the regression rate as well as other performance parameters were investigated. While the burning rate did not change dramatically, both the efficiency and ISP of the motor increased. The local fuel regression rate and the fuel port were also calculated. In addition, instantaneous regression rate was calculated using a special technique.
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(ProQuest: ... denotes formulae omitted.)
1.Introduction
A hybrid rocket motor is a type of chemical propulsion system, a combination of a solid rocket motor and liquid engine. In the classical form of hybrid motor, the solid fuel is embedded in the combustion chamber while the oxidizer, stored in a separate tank in gas or in liquid phase, is injected into the combustion chamber during operation of the motor (Figure 1).
The injection of oxidizer into the combustion chamber, followed by its mixture with the vaporized fuel, produces diffusion flames over the surface of the fuel (Figure 2) [1]. Heat transference from the surface of the flame to the fuel causes continuity of fuel evaporation and sustainability of the combustion. The existence of free space prior to the grain causes complete evaporation of the oxidizer in the combustion chamber before it reaches the grain; hence, the oxidizer enters the port in its gas phase from the beginning. This will cause uniform burning along the grain port, increasing the combustion efficiency. Moreover, this type of chamber configuration improves flame stability, resulting in a decrease in combustion instability by creating a vortex in this region. This chamber, known as the pre-combustion chamber, is considered in most of the experimental and operational hybrid motors [2,3]. According to Figure 2, there is a limited free volume...