Shock tube

About: Shock tube is a research topic. Over the lifetime, 6963 publications have been published within this topic receiving 99372 citations.

On Flow Duration in Low‐Pressure Shock Tubes

Abstract: The severe decrease of flow duration in shock tubes operating at low pressures, previously reported by Duff, is confirmed by experiment and by an analysis of the effects of the laminar-boundary layer behind the shock wave. The latter leads to a shock tube similarity length parameter X, which depends on the tube pressure, diameter and shock Mach number, and to a flow duration parameter T. The theoretical relation T = T(X) is determined and compared with experimental results. From the theoretical result Tmax = 1, the maximum possible flow duration τm in a shock tube is determined; it increases linearly with the initial pressure and the square of the tube diameter and decreases strongly with shock Mach number.

Time Response of Anodized Aluminum Pressure-Sensitive Paint

Abstract: The response time of anodized aluminum pressure-sensitive paint (AA-PSP) was studied to develop the capability of making global pressure measurements in unsteady flow conditions. This pressure-sensitive paint (PSP) uses anodized aluminum as a porous supporting matrix, which improves the response time by increasing the oxygen diffusion process in the PSP layer. A response time of 34.8 μs was obtained from AA-PSP with 4.3-μm matrix thickness. Response times of PSPs were measured from a step change of pressure created by a normal shock wave in a shock tube. The response time of AA-PSP is dependent on the matrix thickness, with a thin supporting matrix giving a fast response time. The increase in surface temperature of the paint caused by shock waves was also measured using a temperature-sensitive paint (rhodamine-B on anodized aluminum) to understand the temperature effect of AA-PSP

The thermodynamic state of the hot gas behind reflected shock waves: Implication to chemical kinetics†

Abstract: Procedures are discussed to correct for nonideality in a shock tube used in the reflected mode in conjunction with flash photolysis and atomic resonance absorption to measure chemical kinetics of atoms at high temperatures Experimentally, pressure time profiles for the incident and reflectedshock regions are made close to the location of the observation windows through which absorbance is measured The corresponding temperatures are calculated from the adiabatic equation of state Justification for this procedure is provided by extending Mirels' boundary layer theory to take intoaccount interaction of the reflected wave with the flowing gas in the free stream and in the boundary layer These theoretical methods are described for calculating the thermodynamic and hydrodynamic states behind the reflected wave from initial values of pressure and temperature and the measured velocity of the incident wave The implication of these results to kinetic measurements at high temperature is discussed

Shock‐Tube Study of the Kinetics of Nitric Oxide at High Temperatures

Abstract: A shock‐tube program was carried out in which the NO concentration was followed as a function of time behind the shock front by absorption of 1270 A radiation, where ground vibrational state O2 and N2 are essentially transparent. The absorption coefficients of the species NO, O2, and N2 as functions of the respective vibrational temperatures were determined by measuring the absorption by the shock‐heated gas at a point in the time history corresponding to complete vibrational relaxation but before the onset of dissociation.Time history analyses were made on a total of 42 shock‐tube runs covering a temperature range of 3000°—8000°K on the following six mixtures: ½% NO, ½% NO+¼% O2, 10% NO, 50% NO, 20% air, and 100% air—the diluent in all cases being argon.An IBM 704 computer was programmed to integrate the vibrational and chemical rate equations as a function of time behind the shock front, subject to the constraints of the conservation equations. The pertinent rate constants were varied in a systematic tr...

Shock tube study of the drag coefficient of a sphere in a non-stationary flow

Abstract: A shock tube facility was used for inducing relatively high acceleration on small spheres laid on the shock tube floor. The acceleration resulted from the drag force imposed by the post shock wave flow. Using double exposure holography, the sphere trajectory could be constructed accurately. Based upon such trajectories, the sphere drag coefficient was evaluated for a relatively wide range of Reynolds numbers (6000≤ Re ≤ 101000). It was found that the value obtained for the sphere drag coefficient were significantly larger than those obtained in a similar steady flow case.