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Titolo: The persistence of regular reflection during strong shock diffraction overrigid ramps
Autore: Henderson, LF; Takayama, K; Crutchfield, WY; Itabashi, S;
 Indirizzi:
 Tohoku Univ, Inst Fluid Sci, Shock Wave Res Ctr, Sendai, Miyagi 9808577, Japan Tohoku Univ Sendai Miyagi Japan 9808577 tr, Sendai, Miyagi 9808577, Japan Univ Calif Berkeley, Lawrence Berkeley Lab, Ctr Computat Sci & Engn, Berkeley, CA 94720 USA Univ Calif Berkeley Berkeley CA USA 94720 & Engn, Berkeley, CA 94720 USA
 Titolo Testata:
 JOURNAL OF FLUID MECHANICS
,
volume: 431,
anno: 2001,
pagine: 273  296
 SICI:
 00221120(20010325)431:<273:TPORRD>2.0.ZU;2S
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 MACH REFLECTION; WAVE REFLECTIONS; STEADY FLOWS; TRANSITION; RECONSIDERATION; VISCOSITY; PARADOX;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Physical, Chemical & Earth Sciences
 Engineering, Computing & Technology
 Citazioni:
 47
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Henderson, LF Tohoku Univ, Inst Fluid Sci, Shock Wave Res Ctr, Sendai, Miyagi 9808577, Japan Tohoku Univ Sendai Miyagi Japan 9808577 yagi 9808577, Japan



 Citazione:
 L.F. Henderson et al., "The persistence of regular reflection during strong shock diffraction overrigid ramps", J FLUID MEC, 431, 2001, pp. 273296
Abstract
We report on calculations and experiments with strong shocks diffracting over rigid ramps in argon. The numerical results were obtained by integrating the conservation equations that included the NavierStokes equations. Theresults predict that if the ramp angle 8 is less than the angle theta, that corresponds to the detachment of a shock, theta < <theta>(e), then the onset of Mach reflection (MR) will be delayed by the initial appearance of a precursor regular reflection (PRR). The PRR is subsequently swept away by an overtaking corner signal (cs) that forces the eruption of the MR which then rapidly evolves into a selfsimilar state. An objective was to make an experimental test of the predictions. These were confirmed by twice photographing the diffracting shock as it travelled along the ramp. We could get a PRR with the first exposure and an MR with the second. According to the vonNeumann perfect gas theory, a PRR does not exist when theta < <theta>(e). A viscous length scale x(int) is a measure of the position on the ramp where the dynamic transition PRR > MR takes place. It is significantly largerin the experiments than in the calculations. This is attributed to the fact that fluctuations from turbulence and surface roughness were not modelledin the calculations. It was found that x(int) > infinity as theta > theta (e) Experiments were done to find out how x(int) depended on the initial shock tube pressure p(0). The dependence was strong but could be greatly reduced by forming a Reynolds number based on x(int). Finally by definition, regular reflection (R) never interacts with a boundary layer, while PRR always interacts; so they are different phenomena.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/11/20 alle ore 20:03:12