矩形蜗壳内三维紊流场的热线测量

HOT-WIRE MEASUREMENT OF 3-D FLOW FIELD IN A RECTANGULAR VOLUTE

在３个不同流量工况，对矩形蜗壳内三维紊流流场进行了测量。结果表明，在矩形蜗壳进口突变截面两侧壁的角区存在有回流区。在回流区中紊动能和雷诺应力明显大于中间截面主流区中的值。随着试验流量的增加，回流区减小，紊动能和雷诺应力很快下降。在同一流量工况，随着半径增加，紊动能和雷诺应力减小。在蜗壳圆周方面的不同横截面上存在有大旋涡，气体在蜗壳中按螺旋管线运动。

D turbulent flow fields in a rectangular volute of a small centrifugal compressor were measured with a hot wire probe at three across sections along its circumference at three different flow regimes.The space positions were adjusted with a three dimensional coordinate frame.Time average velocities and Reynolds stress tensors were calculated by means of a hot wire response equation with third order of precision.The measured results illustrated two recirculation regions near both side walls due to abrupt expansion at the inlet of the rectangular volute.The turbulent kinetic energy and Reynolds stresses in the recirculation regions were reduced as the flow rate increases and as the radius increases.In addition,asymmetry of the rectangular inlet induced the vortices at different cross sections of the volute,and made the trace of the flow as a curved spirochaeta.In consequence,the abrupt expansion and the asymmetry of the inlet must be avoided.