Large Eddy Simulation of Supercritical Mixing and Combustion for Rocket Applications

Abstract

We report on the implementation of the real fluid capabilities to CharlesX, the in-house, unstructured, large eddy simulation code used at the Center for Turbulence Research at Stanford University. A conceptually distinct implementation was needed for the puremixing and the flamelet/progress-variable (FPV) model combustion case. For the nonreacting simulations, a Newton-Raphson based iterative algorithm is used to determine the temperature from the transported density and energy. For the reacting simulations, an extended flamelet table is used that tabulates the departure functions as well as the compressibility factor. These tabulated parameters are used to correct the transported thermodynamic properties. The real fluid extension to CharlesX was used to investigate a non-reacting and a reacting case. In both of these cases, a second-order essentially nonoscillatory (ENO) schemes is locally applied to the flux computation on the faces identified with a dual-threshold relative density sensor. This avoids spurious oscillations of the numerical solution with limited numerical dissipation. This preliminary work illustrates the capability CharlesX to capture the important physics in a typical rocket engine configuration.

A robust and accurate numerical method for transcritical turbulent flows at supercritical pressure with an arbitrary equation of state

“…There are several studies [14,15,18,19] that solve the fully-conservative equations for the transcritical turbulent flows using LES. However, when the transcritical contact surface is numerically captured, the spurious oscillations are generated at the transcritical 90 contact surface.…”

“…In direct numerical simulation (DNS) and large-eddy simulation (LES) of supercritical and transcritical flows, most of the simulations [7,8,9,10,11,12,13,14,15,16,17,18,19] 50 employ cubic equation of state (EoS) models (i.e., written as a cubic function of molar volume), such as the models of Soave-Redlich-Kwong (SRK) [20] type or Peng-Robinson (PR) [21] type of EoS in order to reflect the peculiar thermodynamic variations due to the real fluid effects. Also the fluid transport properties, such as the shear viscosity μ and the thermal conductivity κ, need a model to reflect the unique behaviors especially 55 at the transcritical conditions where the transport properties apart from the models often used in an ideal fluid (e.g., Sutherland's law).…”

Simulation of transcritical fluid jets using the PC-SAFT EoS

“…In [7] a fourth-order central differencing scheme with fourth-order scalar dissipation was applied in order to stabilize the simulation of a cryogenic fluid injection and mixing under supercritical conditions. Moreover, [8] employed an eighth-order finite differencing scheme to simulate homogeneous isotropic turbulence under supercritical pressure conditions, while in [9] a density-based sensor was utilized, which switches between a second-order ENO (Essentially non-oscillatory) and a first-order scheme to suppress oscillations. In the present study a fifthorder WENO (Weighted Essentially Non-Oscillatory) scheme [10] is applied due to its high order accuracy and non-oscillatory behaviour.…”

Modeling Near Critical and Supercritical Fuel Injection and Mixing in Gas Turbine Applications

“…The large variety of scales involved leads to high computational cost of numerical simulations. Hickey et al [9] and Mueller et al [10] developed high-fidelity calculations to simulate supercritical fuel injection. Numerical instabilities are common at the "critical interface" due to large variations of thermophysical properties.…”