RFNC–VNIITF multifunctional shock tube for investigating the evolution of instabilities in nonstationary gas dynamic flows

Abstract

The design, operation, and functionality of the multifunctional shock tube (MST) facility at the Russian Federal Nuclear Center–VNIITF are described. When complete, the versatile MST consists of three different driver sections that permit the execution of three different classes of experiments on the compressible turbulent mixing of gases induced by the (1) Richtmyer–Meshkov instability (generated by a stationary shock wave with shock Mach numbers <5), (2) Rayleigh–Taylor instability (generated by compression wave such that acceleration of the interface is <105g0, whereg0= 9.8 m/s2), and (3) combined Richtmyer–Meshkov and Rayleigh–Taylor instability (generated by a nonstationary shock wave with initial pressure at the front 5 × 106Pa and acceleration of ≤106g0of the interface). For each of these types of experiments, the density ratio of the gases is ρ2/ρ1≤ 34. Perturbations are imposed on a thin membrane, embedded in a thin wire array of microconductors that is destroyed by an electric current. In addition, various limitations of experimental techniques used in the study of interfacial instability generated turbulent mixing are also briefly discussed.

Review of theoretical modelling approaches of Rayleigh–Taylor instabilities and turbulent mixing

“…A crucial problem in the design of experiments and dataset interpretation is the coupling of horizontal l and verticalh scales in the weakly nonlinear regime of RTI and its dependency on the dispersion properties and the initial spectra, including interactions of modes that are in-phase, and modes whose phases are random (Kucherenko et al 2003;Collins et al 2004;Milovich et al 2004).…”

“…Besides, most of the existing experiments and simulations on RTI do not transit completely to the turbulent regime (Dalziel et al 1999;Kucherenko et al 2003;Ramaprabhu & Andrews 2003;Meshkov 2006;Remington et al 2006), whereas the steady motion of the nonlinear bubble of air rising through water with velocity v ∼ gl has been documented by Taylor as early as in 1950 (Davies & Taylor 1950). A trustworthy theoretical description of the nonlinear RTI is required for capturing essentials of the turbulent mixing processes and for identification of robust diagnostic parameters for experiments and simulations (Dimonte et al 2004;Abarzhi et al 2006).…”

Rayleigh–Taylor turbulent mixing of immiscible, miscible and stratified fluids

“…This assumption has no reasonable grounds because RTI is essentially an anisotropic phenomenon: The flow dynamics in the direction of gravity differs from that in the normal plane. 2,3, [14][15][16][17][18][19]29 The growth of horizontal scales in observations 26,27 may indicate a sensitivity of the flow to external boundaries of the fluid tank ͑domain͒ rather than solely to the "merging" character of the mixing. An experimental study of RTI with systematic variation of the aspect ratio of the boundary conditions may clarify this issue.…”

Validation of SPHC and CRASH codes in modeling of linear and non-linear Richtmyer-Meshkov instabilities

“…The fundamental issues to be understood are the evolution and coupling of the large-scale coherent structures and the small-scale structures characterizing RM turbulent mixing [12,13]. Our work studies nonlinear RMI for high Mach number flows and for fluids with contrasting fluid densities, when the effect of the baroclinic vorticity production by the shock wave is the most pronounced [22][23][24][29][30][31]. In our simulations the Mach number ranges from 3 to 10, the Atwood number…”