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.

A global modeling study of solid rocket aluminum oxide emission effects on stratospheric ozone

Abstract: Recent laboratory measurements [Molina et al. 1997] have indicated that the heterogeneous chlorine activation reaction ClONO2+HCl ⟶ HNO3+Cl2 has a reaction probability of about 0.02 on aluminum oxide particles (alumina). Since alumina is among those substances emitted by solid rocket motors (SRMs), we have assessed the heterogeneous chemical impact of SRM-emitted alumina on stratospheric ozone using the Goddard Space Flight Center two-dimensional photochemistry and transport model. Historical launch rates of the Space Shuttle, Titan III, and Titan IV rockets were used in time-dependent and steady-state model calculations. Variations in the temporal ozone decreases reflected the fluctuation in launch rate frequency. The annually averaged global total ozone (AAGTO) is computed to decrease by 0.025% by the year 1997. About one-third of this AAGTO change results from the SRM-emitted alumina while about two-thirds is due to SRM-emitted hydrogen chloride.

A mechanism for unsteady separation in over-expanded nozzle flow

Abstract: Shock wave induced separation in an over-expanded planar nozzle is studied through numerical simulation. These Large-Eddy Simulations (LES) model previous experiments which have shown unsteady motion of the shock wave in flows with similar geometries but offered little insight into the underlying mechanism. Unsteady separation in nozzle flow leads to “side loads” in the rocket engine which can adversely affect the stability of the rocket. A mechanism for the low-frequency shock motion is identified and explained using the LES data. This mechanism is analyzed for a series of over-expanded planar nozzles of various area ratios and nozzle pressure ratios. The effect of grid resolution and Reynolds number on the instability is discussed. A simple reduced order model for the unsteady shock behavior is used to further validate the proposed mechanism. This model is derived from first principles and uses data from the LES calculations to capture the effects of the turbulent boundary layer and shear layer.

Problems in Cool-Down of Cryogenic Systems

Abstract: At the Los Alamos Scientific Laboratory the facilities and technology for handling large quantities of liquid hydrogen are being developed. This project is in support of the Rover program which is a joint endeavor of the Atomic Energy Commission and the National Aeronautics and Space Administration to develop nuclear- powered rocket engines. Since the power for propulsion is to be obtained from the nuclear reaction, the hydrogen, rather than undergoing combustion, is heated by the nuclear reactor and then exhausted through the nozzle. In this manner a specific impulse of about 750 seconds is obtained which can be compared with numbers like 300 seconds obtained when the propellant gas is the product of a chemical reaction. To date three successful tests have been made with reactors using hydrogen gas. Since the weight of containers per pound of propellant can be about 1000 times smaller for liquid storage than gas storage, it is advantageous that the hydrogen be transported as a liquid in a flyable reactor engine. To this end, facilities providing for the testing of reactors with liquid hydrogen are being constructed.

Hybrid rocket system and integrated motor for use therein

Abstract: A hybrid rocket system and motor includes an oxidant tank communicating with a combustion chamber containing a solid fuel grain. The passage from the oxidant tank to the combustion chamber is obstructed by a fill tube which fills the oxidant tank with oxidant and pressurizes it. Once the tank is full, the fill tube is displaced from the tank-chamber passage to deliver oxidant to the grain and initiate the combustion process. The motor may be an integral part of the rocket, or it may be a modular, expendable or exchangeable cartridge-type device inserted into a reusable body.