复合坐标系跨临界液滴表面Kelvin-Helmholtz不稳定增长高效预测方法  

Efficient prediction method for Kelvin-Helmholtz instability growth on transcritical droplet surface in composite coordinate system

作　　者：崔海港 闫啸宇 高岩飞 陈飞 杨世春[1] CUI Haigang;YAN Xiaoyu;GAO Yanfei;CHEN Fei;YANG Shichun(School of Transportation Science and Engineering,Beihang University,Beijing 100191,China;Research Institute of Aero-engine,Beijing University,Beijing 100191,China;Scool of Automotive Engineering,Shandong Jiaotong University,Jinan 250399,China)

机构地区：[1]北京航空航天大学交通科学与工程学院,北京100191 [2]北京航空航天大学航空发动机研究院,北京100191 [3]山东交通学院汽车工程学院,济南250399

出　　处：《北京航空航天大学学报》2024年第9期2835-2842,共8页Journal of Beijing University of Aeronautics and Astronautics

基　　金：国家自然科学基金(T2241003)。

摘　　要：针对混合动力专用内燃机实际运行的跨临界条件,传统方法对于主导可燃混合气形成质量的液滴表面Kelvin-Helmholtz不稳定性分析方法难以实现跨临界宽范围的有效预测。采用复合坐标系方法,建立跨临界强对流环境的等效液滴不稳定性高效预测模型,分别采用全局扩散动力学模型、热力学控制模型及局部液滴表面切向不稳定模型。在全局坐标系模型可以通过模态坐标变换求得解析解,局部坐标系引入势函数等,提高求解速度。而对于可实用性流体计算仿真模型,可通过无量纲物理参数描述不同跨临界条件下空气动力、惯性力、黏性力、表面张力、加速度等控制因素的变化规律,以及其对液滴表面切向和法向不稳定波增长的影响规律。结果表明:液滴表面的空气动力仍然支配着跨临界条件液滴表面切向不稳定波的发展;压力增大时,液相雷诺数控制的流动特性减小与欧尼索控制的液滴黏性力减弱基本抵消;环境温度增加时,雷诺数表征的流动特性对Kelvin-Helmholtz波增长的贡献越来越小,液滴的惯性力影响也越来越弱。Traditional methods for analyzing the Kelvin-Helmholtz instability on the surface of droplets that dominate the formation mass of combustible mixtures are difficult to achieve effective predictions over a wide range of critical conditions for the actual operation of hybrid internal combustion engines.In this paper,the composite coordinate system method was used to establish an efficient prediction model of equivalent droplet instability in a transcritical strong convection environment.The global diffusion dynamics model,thermodynamics control model,and tangential instability model of local droplet surface were used,respectively.The analytical solution could be obtained by the modal coordinate transformation in the global coordinate system model,and the potential function was introduced in the local coordinate system to improve the solution speed.To realize a practical fluid computational simulation model,the dimensionless physical parameters were used to describe the changes in aerodynamic force,inertial force,viscous force,surface tension,and other control factors under different transcritical conditions and analyze their influence on the growth of tangential and normal unstable waves on the droplet surface.The results show that the aerodynamic forces on the droplet surface still dominate the development of tangential unstable waves on the droplet surface under transcritical conditions.When the pressure increases,the decrease in the flow characteristics controlled by Reynolds number in liquid phase and the decrease in the viscous force of the droplet controlled by Ornisol number basically offset.With the increase in ambient temperature,the contribution of flow characteristics controlled by Reynolds number to the growth of the Kelvin-Helmholtz wave becomes small,and the influence of the inertial force of the droplet becomes weak.

关 键 词：复坐标系 跨临界 液滴 表面Kelvin-Helmholtz不稳定 高效预测 

分 类 号：U469[机械工程—车辆工程]