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To achieve high power density and thermodynamic cycle efficiency, the working pressures of liquid-propellant rocket engines, diesel engines, and gas turbines (based on deflagration or detonation) are continuously increasing, which could reach or go beyond the thermodynamic critical pressure of the liquid propellant. For this reason, the studies of trans- and super-critical injection are getting more and more attention. However, the simulation of transcritical phase change is still a challenging topic. The phase boundary, especially near the mixture critical point, needs to be accurately determined to investigate the multicomponent effects on transcritical injection and atomization. This work used our previously developed thermodynamic model based on the vapor-liquid equilibrium (VLE) theory, which can predict the phase separation near the mixture critical point. An \textit{in situ} adaptive tabulation (ISAT) method was developed to accelerate the computationally expensive multicomponent VLE computation such that it can be cheap enough for CFD. The new thermodynamic model was integrated into OpenFOAM to develop a VLE-based CFD solver. In this work, shock-droplet interaction and two-phase mixing simulations are conducted using our new VLE-based CFD solver. The shock-droplet interaction simulation results capture the thermodynamic condition of the surface entering the supercritical state after shock passes through. The atomization of droplets could be triggered by vorticity formed at the droplets' surface. 2D temporal mixing layer simulations show the evolution of the transcritical mixing layer and capture the phase split effect at the mixing layer.
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Conservative and Robust Compact Finite Difference Approach for Simulations of Dense Gas Flows
Supercritical ŕuids have a number of thermodynamic and chemical properties which make them attractive for use in environmentally friendly technologies. However, though the thermodynamic properties of supercritical ŕuids have been studied comprehensively, the dynamics of supercritical and transcritical ŕuid ŕows are less well explored and understood. Studying the behavior of such ŕuid ŕows through high-quality computational investigations could provide crucial insights useful for designing and controlling ŕow systems operating in supercritical and transcritical regimes. An accurate and robust computational framework is a prerequisite to conducting high-quality computational investigations. This work extends a high-ődelity computational framework for ideal gas ŕows by including complex thermodynamic models and realistic transport models near the critical point of the ŕuid where abrupt changes in density and transport properties occur with small temperature or pressure ŕuctuations. The spatial discretization is based on compact őnite difference methods that achieve high-order grid convergence and the high spectral resolution needed to resolve small scale ŕow structures. The computational approach achieves robustness by reducing the aliasing error and improving the spectral resolution of the viscous ŕuxes at high wavenumbers. No non-conservative correction or őltering is needed to maintain robustness for shock-free ŕows if physical or physics-based model dissipation is included. The framework is also compatible with applications of shock capturing schemes and approximated Riemann solvers and supports simulations on curvilinear meshes. Two problems involving compressible free-shear ŕows (temporal mixing layer) and wall-bounded ŕows (zero-pressure gradient ŕat plate boundary layer with a cold isothermal wall) are studied for dense gases to demonstrate the robustness and versatility of the proposed numerical formulation.
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- Award ID(s):
- 2103509
- PAR ID:
- 10441010
- Date Published:
- Journal Name:
- AIAA paper
- ISSN:
- 0146-3705
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.2514/6.2023-3690
