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.

An Active Diagnostic System for Structural Health Monitoring of Rocket Engines

Abstract: An active diagnostic system using built-in piezoelectric actuator/sensor networks was developed for monitoring crack growth in a rocket engine pipe. The diagnostic system combines a sensor network, portable diagnostic hardware and data analysis software which allows for real-time in situ monitoring and long term tracking of the structural integrity of pressure vessels. Experimental data shows that the system can detect a surface crack as small as 4 mm and a through-crack as small as 2 mm in the high pressure engine pipe made of Inconel 718. It was found that the actuator-sensor paths that are most sensitive to crack growth are the ones in which the crack is growing away from, rather than towards the path. This discovery will provide important guidelines for the design of a sensor network for crack detection. It was also observed that the bending mode (equivalent to the A0 mode in plates) is more sensitive than the longitudinal mode (equivalent to the S0 mode in plates) to crack growth.

Experimental Study of Gas-Flow Separation in Overexpanded Exhaust Nozzles for Rocket Motors

Abstract: In a rocket motor having a de Laval nozzle with a fixed expansion ratio, there is only one pressure ratio (p(sub c)/p(sub o)) for which this expansion ratio is correct. At any other pressure ratio the gases will be either underexpanded or overexpanded, depending on whether the pressure ratio is higher or lower than the correct value. Rocket motor flame patterns illustrating the four possible regimes are shown in Figures 1 to 4, inclusive. In Figure 1, the pressure ratio is higher than the correct one for the fixed expansion ratio of the nozzle, resulting in underexpansion of the gases. in Figure 2, the pressure ratio is the correct one. In Figure 3, the pressure ratio is only slightly lower than the correct one, resulting in overexpansion without separation of the gases from the wall. In Figure 4, the pressure ratio is considerably below the correct one, resulting in overexpansion with separation of the gases from the nozzle wall. The present report is concerned primarily with this fourth type of flow, that is, overexpansion of the gases with separation of the flow from the wall. Such a situation exists in a rocket motor operating at a considerably lower altitude than that for which its exhaust nozzle was designed.

First common volume observations of layered plasma structures and polar mesospheric summer echoes by rocket and radar

Abstract: We report the results from simultaneous radar and rocket measurements of a PMSE event where for the first time the rocket measured dust and plasma within the radar beam We find very clear correspondence between the measured dust charge density profile and the radar backscatter profile as a function of height We find that even very small amounts of charged dust is associated with an appreciable PMSE radar backscatter Although we find it likely that the dust layer corresponds fully with the PMSE layer there is a possibility that the upper part of the PMSE layer may be influenced by ion clusters which are too small to be detected by the rocket dust probe

Experimental Study and Simulation of Rocket Engine Freejet Noise

Abstract: On behalf of CNES and in the framework of studies concerning the acoustic environment of Ariane 5 launcher at lift-off, ONERA has adapted to the near sound field simulation a NASA's jet noise model of the 1970's. In order to validate this model, tests have been carried out with static rockets of various sizes. Several improvements appear to be necessary for a precise simulation of the acoustic measurements: in particular, the characteristic length of the model must be reduced and the fully expanded jet data must be used instead of the jet exhaust data. It is shown that the acoustic efficiency, for a given Mach number, is not dependent on the rocket size, and may be estimated from a semi-empirical formula found in the literature. The model changes are checked with other jets of various characteristics. On the basis of experiments and following an approach deduced from an earlier study, the spatial characteristics of the sound field and more particularly the sound power peak location are related to the supersonic length of the flow, which appears to be the adequate reference length for a future jet noise model.

History of U.S. Navy Ramjet, Scramjet, and Mixed-Cycle Propulsion Development

Abstract: A history of high-speed airbreathing propulsion ramjet engines and their respective vehicle and weapon systems developed under the support of the U.S. Navy is presented. These include surface- and air-launched subsonic combustion ramjets, supersonic combustion ramjets (scramjets), and mixed-cycle ramjet/scramjet/rocket engines intended primarily for missile applications for flight speeds from Mach 2 to Mach 8. A summary of the development of the joint Department of Defense/NASA-sponsored National Aerospace Plane is also presented.