Validation study of pressure-measurement system with laser displacement sensor and film

For a conventional surface pressure measurement in a wind tunnel, the following techniques are used: the differential pressure transducer method and the pressure-sensitive paint method. The former affords high-precision results, but is expensive due to the fabrication cost. The latter has a reduced cost; however, the change in the oxygen partial pressure decreases at low speeds. In this paper, a new, low-cost method is proposed to measure the surface pressure under low-speed conditions. In this method, the surface of a model is drilled and a film is attached to the cavity. The film is deflected by the differential pressure between the inner cavity and the outer surface. This differential pressure is calculated by the deflection of the film, which, in turn, is measured by a laser displacement sensor. The measurement accuracy of the sensor depends on the reference length, which is the distance from the sensor head to the target. Three types of laser displacement sensors with reference lengths of 30 mm, 150 mm, and 400 mm were used. The results indicate that the differential pressure can be measured by two laser displacement sensors whose reference lengths are 30 mm and 150 mm. The surface reflection rate of the film and the traverse speed of the measurement were changed to determine their influence on the pressure measurement results.