The 7-hole probe measurement system is mainly used to measure three-dimensional flow fields. During the measurement, the probe head was in direct contact with the measured object, and the head structure had a significant influence on the accuracy of the flow field measurement. The main influencing factors were the hole opening mode, hole position, and hole diameter. For a hemispherical 7-hole probe with perpendicular and forward-facing holes, orthogonal experiments with three levels and three factors (inflow velocity, hole position, and hole diameter) were designed, and additional experiments were conducted on the significant factors. The importance of factors was evaluated based on the correlation between different structural parameters and the pressure coefficient. The experiment was simulated using FLUENT, and the numerical simulation results demonstrated that the square of deviance at the inlet velocity, hole diameter, and hole position was 0.0018, 0.0013, and 0.3611, respectively. The position of the hole has a significant influence on the measurement results, but the influence of the inflow velocity and hole diameter is negligible, and the pressure coefficient is the smallest when the hole is at 45°. For the hemispherical 7-hole probe with forward facing hole, the hole is the best at approximately 45°, and considering the convenience of processing, the diameter of the hole can be selected as the diameter of the 1/10 probe.

The conventional method of measuring a multi-hole probe is based on Bernoulli’s equation and suffers from certain model errors. A computational fluid dynamics-based method was used in this study to reduce the theoretical error and establish a parametric model of the surface pressure of a spherical multi-hole pressure probe for measuring compressible flow fields at supersonic velocities. A flow field inversion method based on the parametric model is proposed herein. Numerical simulations were conducted to validate the proposed method. The experiment results show that in the compressible atmospheric flow field within Mach 1.2–1.7, the measurement errors of the inversion method were 1.3% and 2.35% for velocity and angle, respectively, thus verifying the feasibility of the method. Thus, a new method of measuring multi-hole pressure probe atmospheric flow fields was demonstrated.

As a sensor of a flow field detection system, a 7-hole probe can detect the flow field velocity and retrieve three-dimensional (3D) information of the flow field. Owing to its simple structure and strong environmental adaptability, it is particularly important to calibrate it when it is widely used in turbine machinery, aerospace, and other fields. To detect the 3D flow field in the middle atmosphere, a novel calibration method based on the potential flow theory is designed using a hemispherical 7-hole probe. The hemispherical 7-hole probe was numerically calibrated through numerical simulation, and the coefficients of the calibration equation are provided. In comparison with the traditional 7-hole probe calibration method, the calibration process is significantly shortened while maintaining good measurement accuracy. The velocity error was less than 5% and the angle error was approximately 0.5°.

A multi-hole probe is a very effective sensor for measuring the velocity and direction of a flow field. Compared with other sensors, it has highly reliable, and also a wide range of application prospects. A comparative analysis of probes of different shapes is carried out, where it is found that a hemispherical 7-hole probe with a vertical surface structure opening is the upgrade structure. Based on the spherical structure, a theoretical calibration method for the probe is proposed, and the correlation between the pressure in the hole and the velocity of the flow field is established by a pressure-velocity parameter equation. By calibrating the hemispherical 7-hole probe, it is found that the speed error is less than 5% and the angle error is less than 2°. Compared with other calibration methods, the proposed calibration process is greatly shortened. At the same time, the hemispherical 7-hole probe is used to measure the flow field around a cylinder, where frequency changes of 3.497 Hz, 2.083 Hz and 1.657 Hz are observed in 3 cm, 5 cm and 9 cm cylindrical vortexes, respectively. It is proved that the multi-hole probe also has the ability to detect complex flow fields.