Research Of A Multi-hole Probe Mobile Measurement System

Flow field measurement technology is an important way to study aerodynamic performance of aircraft,Although there are a lot of flow field measurement technologies based on photoelectric technology,the multi-hole probe mobile measurement technology has an unique advantage in many occasions,especially in the flow field which is need to ignoring the contact measurement interference.While compared to the traditional fixed-point measurement methods,this paper provides the concept of the mobile measurement,it has improved optimization of the multi-hole probe for different flow field measurement method can greatly reduce the consumption of manpower,time and other resources in the experiment,which is for expanding the scope of the practical application for the multi-hole probe.Therefore,this paper selects the “research of a multi-hole probe mobile measurement system” as the research subject,compared to the three-hole probe and five-hole probe,seven-hole probe has a higher precision and that can measure a larger angle in the flow field.Thus in this paper,seven-hole probe as the main measurement means to carry out the corresponding research.In this context,In order to improve the miniaturization,high precision and convenience of the probe system,this paper presents the design of a complete seven-hole probe movement velocity measurement system,gives detailed design on the embedded hardware circuit of seven-hole probe velocity measurement system and the Modbus-Communication protocol of the upper and lower computer software system.In the hardware circuit design,this paper uses the design of separating the core board and sensor module to achieve the system miniaturization and improve the anti-jamming capability,uses USB and 485 two kinds of interface and the Modbus protocol to expand the system applications;In the software design,the upper and lower computer software uses digital filtering technology to ensure the measurement accuracy and the introduction of virtual instrument technology to develop the upper computer user program;In the mobile platform design,the T45 series of motion controller as the core sets up a probe scanning coordinate frame to ensure that the system can achieve efficient and accurate mobile measurement.Secondly,taking into account the differences of the sensor in the individual performance,this paper uses the pressure calibration experiment to obtain the pressure coefficient of the sensor,so as to ensure the consistency of the sensor measurement performance.In the K-factor matrix calibration experiment,comparing the data recorded at the time of calibration and the results calculated by the experiment shows that the variation of the pressure data of the probe satisfies the law of the seven-hole probe K-factor matrix calibration experiment.The relative error of the pitch angle and the azimuth angle is within the allowable range,which meets the requirement of the low velocity flow field.And analyzes the error results to summarize the effect of the aperture error of the probe and the measurement error of the sensor on the experimental results.Finally,this paper starts from the dynamic response model to calculate the moving measurement speed within the allowable range of the maximum error of the system dynamic response.Through the numerical calculation of CFD simulation technology and the actual sand blowing experiment,the numerical simulation technology is used to guide the meaning of velocity distribution in the actual flow field.In order to verify the mobile measurement technology further,this paper uses the wing tip vortex as the measurement object to carry out fixed point and the mobile measurement contrast test in the cross section of the flow field,and in which the movement measurement speed is obtained by modeling the allowable scanning speed measurement.By comparing the experimental data of wind tunnel,it is shown that the experimental results of moving measurement and fixed point measurement have high consistency.Therefore,the moving measurement method in this paper is feasible and effective.