Rocket

About: Rocket is a research topic. Over the lifetime, 14018 publications have been published within this topic receiving 95852 citations. The topic is also known as: rockets.

Experimental Study on Spray Characteristics of Gas-Centered Swirl Coaxial Injectors

Abstract: Gas-centered swirl coaxial injectors have become an important subject of study for staged combustion rocket engines with hydrocarbon fuels. While these injectors are employed successfully in rocket engines, it is very rare to find the related research results as applicable to design data. An experimental study on spray characteristics of gas-centered swirl coaxial injectors has been performed. The effects of momentum flux ratio and recess length on the spray characteristics have been investigated by cold flow tests with a photographic technique. The liquid intact length L, which profoundly affects the global spray characteristics, decreases as the momentum flux ratio M increases. The critical momentum flux ratio Mc is introduced to identify the flow patterns as internal or external mixing in the injectors. Concerning the effect of the recess length lR, it is shown that the spray cone angle and the drop size decrease as lR increases.

Progress in Combustion and Heat Transfer Modelling in Rocket Thrust Chamber Applied Engineering

Abstract: The paper outlines the current status of Astrium's combustion and heat transfer prediction tools with special focus on latest model improvements. In particular heat transfer phenomena along overcooled walls including condensation, the modelling of closed cycle engine main combustion chamber injection conditions as well as oxygen/methane combustion and methane cooling prediction capabilities are addressed. First, the progress is manifested by dedicated test case simulations evaluating the extended capabilities by comparison to experimental data. Then, examples are given, how these model improvements contribute to master the challenges of future rocket thrust chambers developments.

Design criteria for film cooling for small liquid-propellant rocket engines.

Abstract: Results of a study to determine the applicability of film cooling to rocket engines in the 10to 1000-lb-thrust range using earth-storable, space-storable, and cryogenic propellant combinations are presented The accuracy of the analytical model was verified with test data using the propellant combinations of nitrogen tetroxide/monomethylhydrazine and fluorine/monomethylhydrazine (N2O4/MMH and F2/MMH) Data are presented which illustrate the interrelational effects of mixture ratio, specific impulse, wall temperature, and the percent of film cooling The studies show that N2O4/MMH and C1F5/MMH and other similar earth-storable propellant combinations are readily adaptable to small film-cooled spacecraft engines The space-storable and deep-cryogenic systems OF2/MMH, OF2/B2H6, OF2/CH4(LPG's), F2/MMH, O2/H2, and F2/H2 will require the use of film cooling and high-temperature materials if the potentially high performance they possess is to be realized Otherwise, the systems have to be operated fuel rich with high percentages of fuel film cooling, which will compromise the deliverable specific impulse and system weight For example, if a 100-lb-thrust F2/H2 engine operating at 100-psia chamber pressure was needed to provide 400 sec of /sp at a mixture ratio of 80 or greater, the minimum percent of film cooling and minimum wall temperature capability of the chamber material must be 40% and 5000QF, respectively

Dynamic Modeling of Hybrid Rocket Combustion

Abstract: The combustion dynamics in hybrid rockets is studied to provide a basic input into transient motor processes. The model treats the time-dependent heat e ow into the ablating fuel surface. A variable surface temperature is considered with an effective activation energy to describe the surface-temperature variation during the transient. Two time scales are observed for throttling: a short lag near the surface related to the activation energy, and the larger well-known thermal lag as a result of conductivity. The model is also applied to an oscillating surface heate ux input. Weobserved an amplie cation oftheregression-rateoscillations for low frequencies.Although thiseffect is not the cause of instability, it can aggravate existing oscillations at these low frequencies. We next formulated a quasisteady combustion model, which is then coupled with thethermal lag system with boundary-layer delaysthat account for the adjustment of the boundary layer to the changes in the freestream conditions and blowing from the surface. A linearized treatment of this coupled system evidences some low-frequency instabilities. The scaling of the oscillation frequencies and the erratic character of the experimentally observed instabilities are successfully explained.