A robust calibration method for seven-hole pressure probes

Multi-hole pressure probe remains an incomparably efficient method of flow measurement due to its simplicity and convenience. An appropriate calibration method is necessary to establish the relations between flow parameters and pressure data. In this paper, a robust calibration method for seven-hole pressure probes is presented, which can also be applied when a hole port is malfunctioning. First, a seven-hole probe was designed and manufactured by 3D printing techniques, and calibration measurements were conducted with a two-degree of freedom calibration apparatus in wind tunnel. Second, theoretical expressions for static pressure coefficients of seven-hole probes were deduced, which guides the establishment of new pressure normalization method in the absence of static and total pressure. Thereafter, a calibration algorithm using the new pressure normalization method was proposed. Finally, effects of sample selection criteria, sample size, and atmospheric static pressure offset on the calibration accuracy of the new algorithm were evaluated. And the case that one port is invalid was studied. Based on the findings obtained from this study, the feasibility and robustness of the new calibration method were validated, and the method can also be easily applied to other multi-hole (including but not limited to seven-hole) pressure probes.