Utilization of Zonal Method for Five-Hole Probe Measurements of Complex Axial Compressor Flows

Abstract

Five-hole probe is widely used in the measurement of turbomachinery flows, but in the traditional way the measurable angle range is not big enough for some interested flows. In this paper, the zonal method is introduced to an L-shaped five-hole probe to measure axial compressor flows. First, the calibration theory of the zonal method in five-hole probe is presented, and the effects of some factors on the measurement accuracy of the five-hole probe are discussed. The results reveal that the two-step correlation method can yield a highest calibration accuracy, and the calibration angular grid spacing should not exceed 5 deg. While the overlap region seems to have no effect on the measurement accuracy of the five-hole probe using the two-step correlation method. Reynolds number (Re) has obvious influence on the measurement accuracy of the investigated five-hole probe, and this effect could be ignored only when Re is bigger than 6000. Then, the investigated five-hole probe using the zonal method is used to measure the inter-row flows of a low-speed large-scale axial compressor, and the measurement results are compared with the results using the traditional method. Besides, the Re corrected results using the zonal method are also compared. The measured results have shown that the zonal method has prominent advantages relative to the traditional method in measuring the corner stall flows. While there is no need to correct the Re effect if the probe is calibrated in the velocity nearly equivalent to the measured flow.