On the transition between regular and Mach reflection in truly non-stationary flows

Itoh, S.; Okazaki, N.; Itaya, Matsuki

doi:10.1017/s0022112081002176

Cited by 53 publications

(33 citation statements)

References 8 publications

(10 reference statements)

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“…There is no analytical model available so far for the reflection over cylindrical convex surfaces. A simple numerical code by Itoh, Okazaki & Itaya (1981) was found to well agree with experimental results in the range 1 < M s < 1.25.…”

Section: R1-2supporting

confidence: 54%

The non-stationary hysteresis phenomenon in shock wave reflections

2013

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The non-stationary transition from Mach to regular reflection followed by a reverse transition from regular to Mach reflection is investigated experimentally. A new experimental setup in which an incident shock wave reflects from a cylindrical concave surface followed by a cylindrical convex surface of the same radius is introduced. Unlike other studies that indicate problems in identifying the triple point, an in-house image processing program, which enables automatic detection of the triple point, is developed and presented. The experiments are performed in air having a specific heats ratio 1.4 at three different incident-shock-wave Mach numbers: 1.2, 1.3 and 1.4. The data are extracted from high-resolution schlieren images obtained by means of a fully automatically operated shock-tube system. Each experiment produces a single image. However, the high accuracy and repeatability of the control system together with the fast opening valve enables us to monitor the dynamic evolution of the shock reflections. Consequently, high-resolution results both in space and time are obtained. The credibility of the present analysis is demonstrated by comparing the first transition from Mach to regular reflection (MR → RR) with previous single cylindrical concave surface experiments. It is found that the second transition, back to Mach reflection (RR → MR), occurs earlier than one would expect when the shock reflects from a single cylindrical convex surface. Furthermore, the hysteresis is observed at incident-shock-wave Mach numbers smaller than those at which the dual-solution domain starts, which is the minimal value for obtaining hysteresis in steady and pseudo-steady flows. The existence of a non-stationary hysteresis phenomenon, which is different from the steady-state hysteresis phenomenon, is discovered.

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Section: R1-2supporting

confidence: 54%

The non-stationary hysteresis phenomenon in shock wave reflections

2013

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“…The transition process from regular to Mach reflection, RR → MR, and the reverse process, MR → RR, over circular surfaces have been the focus of many studies over the past four decades (Ben-Dor, Takayama & Kawauchi 1980;Ben-Dor & Takayama 1981;Itoh, Okazaki & Itaya 1981;Gvozdeva, Lagutov & Fokeev 1982;Takayama & Sasaki 1983;Ben-Dor & Takayama 1986Gruber & Skews 2013). This transient problem caught the interest of many researchers due to the fact that experimental findings show significant discrepancies in the pseudo-steady predictions of the RR → MR transition position (Geva, Ram & Sadot 2013;Kleine et al 2014).…”

Section: Transient Shock Reflectionmentioning

confidence: 99%

High spatial and temporal resolution study of shock wave reflection over a coupled convex–concave cylindrical surface

2015

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Studying the nature of transient reflections of shock waves from surfaces is important in many engineering fields, e.g. blast protection, supersonic flights, shock focusing, medical and industrial applications and more. The recent advancements in this field reveal that the major obstacle in better understanding this phenomenon by means of experimental investigations is the limited temporal and spatial resolution. An alternative approach to commonly used high-speed photography is based on the use of a single-lens reflex (SLR) camera that captures only one image per experiment. Using this method to study a transient reflection process necessitates repeating each experiment many times while retaining extremely high repeatability. In the present study, we present a solution to this obstacle by means of a fully automated shock tube facility, which has been developed in the course of this study. A typical experiment can be executed a few hundred times with a repeatability of less than 0.01 in the incident-shock-wave Mach number at moderate shock strengths (M = 1.2-1.4). The system offers a very high spatial and temporal resolution description of the transient reflection process of a shock wave over a coupled convex-concave surface. The study of this complex configuration using a fully automated shock tube enables one to observe, in greater detail than ever before, both the transient transition from regular reflection, RR, to Mach reflection, MR, and the reverse transient transition from MR to RR. The geometry studied can also be found in blunt leading-edge reflectors in which higher pressures were recorded, and the results presented also describe in detail the shock reflection process inside such a reflector. The results highlight and strengthen the recent understanding of the importance of high spatial and temporal resolution in determining the transition process from RR to MR over a coupled concave-convex surface. However, despite achieving very high statistical certainty in the experimental measurements, the question of the difference between the pseudo-steady transition criterion and the experimental results remains unresolved.

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“…If convex surfaces are used then the flows are truly non-stationary and do decay. Experiments of this type have been done by Ben-Dor et al (1980) and Itoh et al (1981). The decay of the shocks is attributed to the following expansion waves and not viscosity effects, and apparently they are also responsible for the delay in transition.…”

Section: Transition Between Regular and Irregular Wave Interactionmentioning

confidence: 99%

Experiments on the interaction of a pair of cylindrical weak blast waves in air

Higashino¹,

Henderson

Shimizu³

1991

Shock Waves

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Abstract. This paper reports the results of experiments and computations on the interaction of a pair of cylindrical blast waves in air. The waves were generated by exploding wires, and both symmetrical and unsymmetrical interactions were observed. The experimental data includes schlieren photographs of the wave interactions, their radii, shock Mach number and pressure versus time, as well as various cross plots and data on the shock regular/irregular interaction transition condition. The flow fields were computed with the help of the "Total Variation Diminishing'' (TVD) method, and appear to represent the experimental results reasonably well. Some attention is also given to the blast scaling laws of the type discussed by Sakurai (1965) and Oshima (1960).

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On the transition between regular and Mach reflection in truly non-stationary flows

Cited by 53 publications

References 8 publications

The non-stationary hysteresis phenomenon in shock wave reflections

The non-stationary hysteresis phenomenon in shock wave reflections

High spatial and temporal resolution study of shock wave reflection over a coupled convex–concave cylindrical surface

Experiments on the interaction of a pair of cylindrical weak blast waves in air

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