Static Characteristics of the Air Gauging Sensor Applied in the Microhole Measurement

摘要

Microhole measurement methods struggle to produce the intended results because of poor in situ measurement circumstances. The back-pressure air gauge, which is self-clean and unaffected by complicated environments, can be equipped with a microprobe to obtain desired results, but the limited application of the sensor is caused by its expensive cost and challenging processing requirements. In this article, an air gauging sensor without a microprobe was presented as a low-cost and simple structure solution to the above issue and the static characteristics were optimized in several methods accounting for different microhole diameters. Theoretical and experimental static characteristics were obtained using the steady-state model and experimental data. Then, the effects of crucial parameters on static characteristics, including the feeding pressure and the inlet nozzle diameter, were analyzed under various settings. A novel performance improvement method of the sensor was presented by comparing and analyzing the Px = f (d1) and Px = f (d1 2) characteristics. The results indicated that a smaller inlet nozzle and appropriately higher feeding pressure helped improve the sensitivity, reduce the starting diameter, and enlarge the length of the linear area. The novel method of extending the measurement range by combining Px = f (d1) with Px = f (d1 2) has a larger measurement range and a smaller starting diameter than sacrificing 1 nonlinear error. It is possible to use the nonlinear area to measure microholes much smaller than the starting diameter. These new findings make contributions to the wide application of the air gauging sensor in microhole measurements.