China
Africa
Explore chapters and articles related to this topic
Rocket Engines
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
A bipropellant rocket unit has two separate liquid propellants: an oxidizer and a fuel; see Figure 19.9b. They are stored separately and are not mixed outside the combustion chamber [1]. The majority of liquid-propellant rockets have been manufactured for bipropellant applications, which have the following features:Fuel and oxidizer are pumped into the combustion chamber.Often use turbopumps.Power tapped from main combustion.Injectors mix propellant to provide stable and thorough combustion.Heat is generated from combustion.Heated products are expelled out of the nozzle.
A Numerical Study on Hypergolic Combustion of Hydrazine Sprays in Nitrogen Tetroxide Streams
Published in Combustion Science and Technology, 2018
Hiroumi Tani, Hiroshi Terashima, Yu Daimon, Mitsuo Koshi, Ryoichi Kurose
Bipropellant chemical thrusters, used for the attitude control and orbit maneuvering of spacecraft, are operated using both long-term steady-state and pulse mode firing with firing times of the order 101–103 s and 10–2–10–1 s, respectively. Many bipropellant thrusters employ hydrazine (N2H4) or monomethylhydrazine (MMH and CH3NHNH2) as a liquid fuel and nitrogen tetroxide (NTO) as a liquid oxidizer. The combination of the fuel and oxidizer exhibits a unique and characteristic chemical reaction called “hypergolicity” (Davis and Yilmaz, 2014; Sutton and Biblarz, 2001), whereby the fuel and oxidizer spontaneously auto-ignite upon contact with each other, even at low temperatures and low pressures. Therefore, the cyclic process of ignition and quenching in the pulse mode can be operated without an igniter and catalyst. To take advantage of hypergolicity, the bipropellant thrusters generally employ unlike impingement-type injectors (Sutton and Biblarz, 2001), as shown in Figure 1. The chamber and injector are carefully designed to obtain high combustion efficiency in the steady-state mode and fast ignition response in the pulse mode. However, thruster manufacturers still screen many trial products of thrusters through time- and money-consuming firing tests because little is known about the multi-physics phenomena of the hypergolic impinging jets. These include reactive liquid jet atomization and spray formation (Chen et al., 2013; Tani et al., 2017), the liquid-phase reaction at impinging regions (Dambach et al., 2013), droplet combustions (Lawver and Breen, 1967; Solomon et al., 2013), and gas-phase reactions (Daimon et al., 2014; Kanno et al., 2015; Sawyer and Glassman, 1967). Therefore, the fundamental sub-processes require further investigation entailing experiments and numerical simulations.