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摘要
In this paper, a comprehensive highly compressible and turbulent two-fluid multispecies model is presented. It involves an equation for the transport of the liquid volume fraction in addition to two different sets of partial differential equations for the gas and the liquid phase. The multicomponent gas phase is governed by an ideal gas equation of state (EOS) while the stiffened gas EOS is specified to the single-component liquid phase. In this work, a Reynolds averaged Navier-Stokes (RANS) formulation is adopted. For the turbulence, a standard k - epsilon model is used for the gas phase while a turbulent viscosity-based model is used for the liquid phase in order to improve the laminar turbulent transition computation through the nozzle. In addition, the model equations include different relaxation terms for mass, momentum, and energy exchanges at the liquid gas interfaces. For the present cavitation modeling, an instantaneous relaxation procedure is used for the velocity, pressure, and temperature; while a slower procedure is adopted for the Gibbs free-energy relaxation model (GERM) at the interfaces. These models have been applied for the simulation of the cavitation inside a transparent single-hole nozzle. The obtained cavitation pocket has a similar shape as the experiments. Moreover, two different cavitation regimes have been identified. A gaseous cavitation regime appears in a region in which the static pressure is close to but above the liquid saturation pressure; a second cavitation regime may happen when the static pressure goes below the liquid saturation pressure. In the latter case, the liquid become superheated and leads to a vaporous cavitation regime. Also, the cooling of the fuel and the density variation due to the expansion of compressible liquid through the nozzle is among the more interesting findings of this paper.
- 出版日期2015
