带方向的气流有序均匀性评价方法

针对发动机进气道气流质量评价提出一种基于空气流速分布方向的气流有序均匀性评价方法,即先将空气流速投影到约定方向,再结合均方差定义的均匀性指数γ、克里斯琴森均匀系数CU、相对标准偏差CV三种传统均匀性评价指标计算各测点速度偏离预期速度的程度.分别用传统均匀性评价指标和带方向的气流有序均匀性评价方法对发动机进气道改良前后气流有序均匀性进行评价,结果表明:带方向的气流有序均匀性评价方法较传统指标更能明显地表明进气道改良后的气流有序性.发动机外特性实验表明:进气道改良后燃油消耗率降低,与带方向的气流有序均匀性评价方法的结论一致.因此,带方向的气流有序均匀性评价方法能有效地评价发动机进气道气流质量.

Evaluation method for ordered uniformity of air flow with direction

Aimed at evaluating air flow quality in engine inlet,a new evaluation method for ordered uniformity with direction of air flow based on air flow velocity distribution direction is proposed.Air flow velocity is projected to a prescribed direction,and then the divergence between the measurement velocity and the expected is calculated based on three traditional uniformity evaluation indices the evenness index y,the Christiansen uniformity coefficient CU and the relative standard deviation CV.Ordered uniformity is evaluated before and after the improvement of engine inlet with the traditional uniformity evaluation indices and the new method.Experimental results show that the evaluation based on the new method is more obviously than the traditional indices.The engine external characteristic test shows that the fuel consumption rate is decreased after the inlet is improved and it is the same with the conclusion by the new evaluation method.So,the evaluation method for the ordered uniformity with direction of the air flow can effectively evaluate the air quality of the engine inlet.