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.

Aerothermochemical analysis of carbon-carbon nozzle regression in solid-propellant rocket motors

Abstract: An aerothermochemical analysis for the process of carbon-carbon composite material regression in large advanced solid-propellant rocket motors has been conducted. The analytical approach is similar in spirit to the approach of Klager, Keswani, and Kuo, with the main idea of the nozzle regression being due to the carbon chemical attack by H2O. The different steps of the work have consisted of the development and applications of several numerical codes substantiated by experimental results concerning the regression rate and the surface roughness of a carbon-carbon material. The calculated results show good agreement between measured data and the predicted regression when a flow transition is assumed, in the model, between a laminar boundary layer existing on the "smooth" virgin carbon-carbon material at the firing start and a turbulent boundary layer existing on the very rough ablative carbon-carbon surface during stabilized motor operation.

The Problem of Escape from the Earth by Rocket

Abstract: The problem of imparting to a given pay load the necessary velocity to escape from the earth is re-examined in the light of recently released information on wartime rockets. The fundamental equations of motion of a rocket in outward radial flight are derived and the influence of each of the following design parameters is examined: c, the effective jet velocity; {', the ratio of propellant mass to initial mass; tVt the time of powered flight; M, the ratio of initial mass to maximum cross-sectional area; and C^, the drag coefficient based on the same cross-sectional area. The exhaust velocities attainable under standard conditions with rocket propellants range between 6,200 ft. per sec. for nitric acid-aniline and 10,200 ft. per sec. for oxygen-hydrogen, the former being representative of dense propellants and the latter of light propellants. On the basis of the design characteristics of the V-2 rocket, it is believed tha t the maximum practical value of £ tha t may be realized is about 0.85. Therefore, it is concluded that single-step rockets utilizing propellants that develop their energy by chemical reaction cannot escape from the earth. Escape may be accomplished by single-step rockets, however, if nuclear sources of energy can be used to heat gases of low molecular weight in order to provide much higher exhaust velocities. The analysis is extended to calculate the velocity achieved by a multiple-step rocket. The overall mass of the rocket and the maximum velocity of the last step are related to the number of steps and to the ratio of the masses of successive steps. I t is shown tha t the necessary velocity can be attained with any of the rocket propellants available by proper choice of the number of steps. Various examples of multiple-step rockets capable of projecting instrumental pay loads away from the earth are presented.

Coupled Wall Heat Conduction and Coolant Flow Analysis for Liquid Rocket Engines

Abstract: Coolant flow modeling in regeneratively cooled rocket engines fed with turbo machinery is a challenging task because of the high wall temperature gradient, the high Reynolds number, the high aspect ratio of the channel cross section, and the heat transfer coupling with the hot-gas flow and the solid material. In this study the effect of wall heat conduction on the coolant flow is analyzed by means of coupled computations between a validated Reynolds-averaged Navier–Stokes equations solver for the coolant flowfield and a Fourier’s equation solver for the thermal conduction in the solid material. Computations of supercritical-hydrogen flow in a straight channel with and without coupling with the solid material are performed and compared to understand the role played by the coupling on the coolant flow evolution. Finally, the whole cooling circuit of the space shuttle main engine main combustion chamber is analyzed in detail and discussed for the sake of comparison of results obtained with the present couple...