Topic
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.
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TL;DR: In this article, the stability boundary of a straight solid propellant rocket chamber has been investigated in the case of small amplitude standing waves, where both pressure and velocity coupling are accommodated, although the response function for velocity coupling is not yet known.
Abstract: Of the various unstable motions observed in solid propellant rocket chambers, the most troublesome
currently are those involving oscillatory motions parallel to the axis. Such instabilities are found to arise particularly
in larger rockets using propellants which contain aluminum. The problem is formulated here in one-dimensional
form and solved for the case of small amplitude standing waves. Both pressure and velocity coupling
may be accommodated, although the proper description of the response function for velocity coupling is not yet
known. In addition to several special cases, the stability boundary is discussed for a straight chamber having
variable cross section. The influences of the mean flow field, the nozzle, particulate matter, and motions of the solid propellant grain are taken into account.
134 citations
TL;DR: A phosphorus-doped silicon crystal of 8 mm diameter and 10 mm length has been grown by the floating zone method at a rate of 5 mm/min during the (6 min) weightless phase of a rocket flight as discussed by the authors.
133 citations
20 Jun 1999
TL;DR: In this article, the transition from free shock separation to restricted shock separation and vice versa is discussed, and the cap shock pattern is identified to be the cause of this transition, which turns out that this pattern can be interpreted as an inverse Mach reflection of the internal shock at the centerline.
Abstract: Flow separation in nozzles of rocket engines is undesired because it can lead to dangerous lateral forces, which might damage the nozzle The origin of side-loads is not fully clear, although different possible origins were identified in the past Meanwhile, it seems to be clear that in thrust-optimized or parabolic nozzles, a major side-load is due to the transition of separation pattern from free shock separation to restricted shock separation and vice versa After a literature review, the reasons for the transition between the separation patterns are discussed, and the cap shock pattern, which is identified to be the cause of this transition, is closely analyzed It turns out that this pattern can be interpreted as an inverse Mach reflection of the internal shock at the centerline The separation and side-load behavior of thrust-optimized and parabolic nozzles is described in detail In order to be able to predict the pressure ratio pc/pa at which the transition of separation patterns occurs, a model is developed which uses TDK-data as an input With the oblique shock relations and a momentum balance, both the ratio of chamber to ambient pressure and the value of the lateral force can be predicted with fair accuracy
133 citations
TL;DR: In this article, a high pressure bipropellant rocket engine was successfully micromanufactured by fusion bonding a stack of six individually etched single crystal silicon wafers, achieving a thrust power of 750 W. In order to test the device, an innovative packaging technique was developed to deliver liquid coolant and gaseous propellants to the rocket chip at pressures in excess of 200 atm at temperatures above 300°C.
Abstract: A high pressure bipropellant rocket engine has been successfully micromanufactured by fusion bonding a stack of six individually etched single crystal silicon wafers. In order to test the device, an innovative packaging technique was developed to deliver liquid coolant and gaseous propellants to the rocket chip at pressures in excess of 200 atm at temperatures above 300°C. Testing continues on the 1.2 g devices, which have been run to date at a chamber pressure of 12 atm, generating 1 N of thrust, and delivering a thrust power of 750 W.
131 citations
TL;DR: In this paper, the authors report experimental observations of oscillations produced by a fuel nozzle typical of industrial gas turbines and evaluate how geometric changes to the fuel nozzle will affect the boundary between stable and oscillating combustion.
Abstract: The use of premix combustion in stationary gas turbines can produce very low levels of NO{sub x} emissions. This benefit is widely recognized, but turbine developers routinely encounter problems with combustion oscillations during the testing of new premix combustors. Because of the associated pressure fluctuations, combustion oscillations must be eliminated in a final combustor design. Eliminating these oscillations is often time-consuming and costly because there is no single approach to solve an oscillation problem. Previous investigations of combustion stability have focused on rocket applications, industrial furnaces, and some aeroengine gas turbines. Comparatively little published data is available for premixed combustion at conditions typical of an industrial gas turbine. In this paper, the authors report experimental observations of oscillations produced by a fuel nozzle typical of industrial gas turbines. Tests are conducted in a specially designed combustor capable of providing the acoustic feedback needed to study oscillations. Tests results are presented for pressures up to 10 atmospheres, theoretical considerations, it is expected that oscillations can be characterized by a nozzle reference velocity, with operating pressure playing a smaller role. This expectation is compared to observed data that shows both the benefits and limitations of characterizing the combustor oscillating behavior in termsmore » of a reference velocity rather than other engine operating parameters. This approach to characterizing oscillations is then used to evaluate how geometric changes to the fuel nozzle will affect the boundary between stable and oscillating combustion.« less
127 citations