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为模拟旋转体结冰问题的过冷水滴运动及撞击过程,基于欧拉方法及单旋转坐标系模型,建立了三维旋转水滴运动模型,并提出了相应的数值求解方法。采用单旋转坐标系对空气及水滴两相流动过程进行处理,通过引入惯性力,将惯性系下的周期转动边界转换为定常流动边界;利用欧拉方法,使用单向耦合形式描述空气—水滴流场;在单旋转坐标系下,向控制方程内引入科里奥利加速度及牵连加速度,进行非惯性系下欧拉方程的修正,从而描述水滴运动过程;采用有限容积求解器对空气及水滴运动的控制方程组进行求解,通过引入源项定义单旋转坐标系下的惯性力,得到空气流场及水滴场的速度、体积分数分布,进而得到表面水滴撞击特性。采用上述方法对旋转帽罩与叶片模型进行算例分析,结果表明所建立的旋转水滴计算方法有效,对比静止状态表面的结果,旋转对帽罩的水滴撞击特性影响甚小,而对桨叶存在显著影响;由于帽罩具有中心对称的特性,因而旋转带来的切向速度变化对其水滴撞击特性影响不明显;桨叶表面水滴收集系数随旋转角速度增大而增大,同时收集系数在表面的分布会向迎风方向偏移,较大的角速度对应了更为显著的收集系数增幅与偏移现象。
In order to simulate the subcooled droplet motion and the impact process of the icing rotor freezing problem, a three-dimensional rotating droplet motion model is established based on the Euler method and the single-rotation coordinate system model, and a corresponding numerical solution method is proposed. The single-rotation coordinate system is used to process the two-phase flow of air and water droplets. By introducing the inertial force, the periodic rotation boundary under the inertial system is transformed into the steady flow boundary. Using the Euler method, the unidirectional coupling is used to describe the air- Field; Coriolis acceleration and implicative acceleration are introduced into the control equation under the single-rotation coordinate system to modify the Euler equations under non-inertial system, so as to describe the movement of water droplets. The finite volume solver is used to measure the movement of air and water droplets The control equations are solved by introducing the source term to define the inertial force in the single-rotation coordinate system, and the velocity and volume fraction distributions of the air flow field and the drip field are obtained, and the impact properties of the surface droplet are obtained. The above method is used to analyze the rotating cap and the blade model. The results show that the established spin-drop calculation method is effective. Compared with the stationary surface, the rotation has little effect on the drop impact characteristics of the cap, The influence of the tangential velocity caused by the rotation on the impact characteristics of the droplet is insignificant due to the central symmetry of the cap. The collection coefficient of the droplet on the blade surface increases with the increase of the rotational angular velocity, and the collection coefficient increases at the surface The distribution will shift to the windward direction, the larger angular velocity corresponds to the more significant increase and offset of the collection coefficient.