Numerical simulation of the growth and interaction of vapour bubbles in superheated liquid jets

被引:8
作者
Dietzel, D. [1 ]
Hitz, T. [2 ]
Munz, C. -D. [2 ]
Kronenburg, A. [1 ]
机构
[1] Univ Stuttgart, Inst Tech Verbrennung, Herdweg 51, D-70174 Stuttgart, Germany
[2] Univ Stuttgart, Inst Aerodynam & Gasdynam, Pfaffenwaldring 21, D-70569 Stuttgart, Germany
关键词
Flash boiling; Level-set; Multiphase flow; Bubble growth; Bubble interaction; SHARP-INTERFACE METHOD; PHASE-TRANSITION; 2-PHASE FLOW; DYNAMICS;
D O I
10.1016/j.ijmultiphaseflow.2019.103112
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
Operating fluids for steering and propulsion of orbital manoeuvring systems are to be changed from toxic substances to environmentally less harmful alternatives. Liquid oxygen (LOX) can be used as oxidizer but the near vacuum conditions of outer space lead to a fast expansion into a superheated state when LOX is injected into the combustion chamber. The disintegration of the liquid jet is driven by bubble nucleation and growth, which is called flash boiling. These processes typically occur at small length and time scales and need to be modelled in macroscopic simulations of the entire combustion chamber. The goal of the present work is a quantification of bubble growth rates and bubble-bubble interactions that can be used to improve the existing submodels needed for full-scale simulations of the entire thruster. We use direct numerical simulations (DNS) of bubble clusters and compare the resulting growth rates to standard models for single bubble growth. The DNS solver is based on a discontinuous Galerkin approach and combined to a level-set equation to transport the interface between liquid and vapour. A modified HLLC Riemann solver accounts for the phase transfer. The computations show that vapour bubbles grow more slowly in the center of a jet than at its surface. The bubble radii exponentially decrease with distance from the liquid jet interface and growth rates are reduced by more than 70% in the center of the jet such that their volumetric expansion can be neglected for the computation of the jet expansion. The reduced growth can be associated with the interactions of the pressure fields surrounding the bubbles as the liquid pressure increases due to bubble growth and evaporation. The degree of superheat is locally reduced and bubbles grow at a smaller rate. The growth rates of individual bubbles can be parameterised with the local degree superheat, which may serve as a potential sub-scale model. These findings hold for various operating conditions that are characteristic for LOX flash evaporation under vacuum conditions. (C) 2019 Elsevier Ltd. All rights reserved.
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页数:14
相关论文
共 43 条
[41]  
Toro E. F., 2013, Riemann Solvers and Numerical Methods for Fluid Dynamics: A Practical Introduction
[42]  
Yeoh GH, 2010, COMPUTATIONAL TECHNIQUES FOR MULTI-PHASE FLOWS: BASICS AND APPLICATIONS, P1
[43]   Validation of a Three-Dimensional Internal Nozzle Flow Model Including Automatic Mesh Generation and Cavitation Effects [J].
Zhao, Hongwu ;
Quan, Shaoping ;
Dai, Meizhong ;
Pomraning, Eric ;
Senecal, P. K. ;
Xue, Qingluan ;
Battistoni, Michele ;
Som, Sibendu .
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, 2014, 136 (09)