Experimental study on pressure fluctuation sensor-based diagnostic for boundary layer transition with long-fine tubing system

Low speed flow transition zone of boundary layer can be detected by means of pres-sure fluctuation measurement over the surface of the test model.It is convenient that fluctuation pressure transducers are arranged outside the model through long-fine tubing system.The distor-tion of pressure signal caused by the tubing system should be recognized.Under the static condi-tion(V= 0m/s),the authors measured a series of sound signals over an airfoil model surface through the tubing system.The sound signal source come from a speaker actuated by a signal generation.The model chord length is 0.8m and the model span is 1.6m in length.The tubes are about 1.2m long and their inner diameters are 0.8mm.The tubing system has proved to be able to transmit the characteristics of the surface pressure fluctuation for the transition detection.Un-der the condition of section flow velocity V= 30m/s,signals of the surface pressure fluctuation transmitted along the chord of the model were measured and the boundary layer transition zones were located.This experiment was conducted in NF-3 low-speed wind tunnel of Northwestern Polytechnical University.The authors suggest that the pressure fluctuation transition diagnostic method with long-fine tubing system is promising and further researches should be carried out.