结构因素对离心通风器性能影响的数值研究

在高转速下,航空发动机离心通风器内腔存在强烈的湍流流动,而稳定工作后通风器内腔中漩涡呈周期性产生和淹灭。小尺寸颗粒受流体微团湍流随机脉动的影响,产生相对于平均流的随机脉动运动。为了研究通风孔偏心距和辐板顶圆半径对通风器性能的影响,采用离散相模型(DPM)模拟通风器内颗粒的运动轨迹。并应用随机游走(DRW)模型模拟连续相湍流瞬时速度脉动对颗粒轨迹的影响,采用随机涡寿命模型确定随机追踪模型的积分时间。结果表明:辐板顶圆半径的增大有助于提高通风器的分离效率,同时也增大了腔内流通阻力;通风孔偏心距对减小通风阻力的作用明显,但降低了离心通风器的分离效率。

Numerical Study on Efficiency of Centrifugal Breather's Performance by Structural Factors

In high-revolution conditions, there is a strong turbulence flow in the centrifugal breather of a turbine engine, and in a stable condition, the eddy in the centrifugal breather forms and vanishes periodically. Influenced by the random pulsation of fluid particles,small sized particles will start a relatively random pulsation compared with the main motion. In order to study the influence of aeration holes eccentricity and radial plate top radius on breather performance, adopt the Discrete Phase Model (DPM) to simulate the motion trajectory of particles in the centrifugal breather, and used random walk (DRW) model to simulate the instantaneous velocity pulsation's influence on particle trajectory in the continuous phase turbulence, with random vortex life model to determine the integral time of random tracking model. The results show that, increasing the radius on the top of the web plate improves the separation efficiency of breather, but meanwhile increases the flow resistance of the cavity as well. The effect of using ventilation hole eccentricity in reducing the flow resistance is very obvious, but also reduces the separation efficiency of centrifugal breather.