前缘弯掠风扇叶尖涡的数值分析与PIV实验

本文采用三维Navier-stokes方程、κ-ε两方程湍流模型和SIMPLE算法,对空调用前缘弯掠开式斜流风扇转子叶尖涡的三维流动特性进行了数值分析与PIV实验测量。结果表明:沿子午面流动的主气流与从叶顶外侧吸入的气流之间的卷吸作用导致在吸力面叶顶区域产生了叶尖涡。叶尖涡从25％叶顶弦长位置到50％弦长位置不断发展,同时沿吸力面向下游移动;叶尖涡随后逐渐向压力面移动;叶尖涡从75％叶顶弦长位置至转子下游逐渐耗散,沿着一条与叶轮旋向相反的斜线向转子下游发展,大致持续到转子下游65％叶顶弦长位置。计算结果和PIV的实测结果吻合,表明用 CFD工具可以预测流场,同时为前缘弯掠开式斜流转子在大型中央空调室外机上的应用和风机系统的优化设计及其降噪提供了重要的内流数据。

AN INTEGRATED NUMERICAL AND EXPERIMENTAL STUDY OF TIP VORTEX FLOW IN A FORWARD SKEWED-SWEPT FAN

This paper analyzed the three-dimensional flow phenomena of tip vortex of an open skewed swept diagonal flow fan in an air-conditioner by means of GFD simulation and PIV. Numerical analysis was based on the three-dimensional Navier-Stokes equations coupled with Turbulence model. Pressure and velocity are coupled by SIMPLE method. The results showed that, the tip vortex at the blade's leading edge near the suction surface tip region is generated by the rolling up effects between the main flow fluid along the meridian surface and the outer fluid of the blade's outer region. The tip vortex persistency develops from the position of 25% tip chord length to the position of 50% tip chord length, and moved towards the downstream of the rotor exit and the pressure surface. The vortex dissipation began at the position of 75% tip chord length, extended to the downstream of the rotor in a slant line contrary to the rotor's rotation direction, and disappeared at 65% tip chord length of the downstream of the rotor exit. In addition, by comparing numerical results and PIV results, a good agreement between them indicated a possibility to predict a flow field with CFD tools. The numerical analysis and experimental results provided the important internal flow data for the application, optimization and the noise reduction of the leading edge skewed-swept diagonal flow fan on the outdoor unit of the centralized air conditioners.