Point Detection Technique, Based On Micro-sensor Array Of Boundary Layer Separation

The detection of the location of the separation point of the boundary layer is very important, which is used for active flow control and smart skin adaptive control system. The design and integration methods of micro thermal sensor array, sensor array driver circuit, dynamic data acquisition circuit, and criterion algorithm of the boundary layer separation point were presented in the thesis.Firstly, based on the characteristic of the separation of the boundary layer, the criterions of boundary layer separation point were determined. The thickness of the boundary layer was estimated to propose the design constraint of the measure sensor. Two methods of online measurement principle were compared, and micro thermal film sensor based on thermal exchange principle was adopted.Secondly, a new integration method of flexible micro thermal sensor array was proposed, and flexible sensor array was fabricated by above new method. Micro thermal film sensor's dynamic frequency response which based constant current and constant temperature driver mode was studied;the analysis demonstrated the constant temperature mode was the better.Then, the constant current driver circuit and constant temperature circuit were designed, and which were compared mutually;constant current driver circuit was adopted because of simple integration structure. THS1206 ADC was used to design the high speed dynamic data acquisition system based TMS320VC5416 DSP, and the peripheral circuits of DSP were also extended for real-time of detection system.In the end, based on the above criterions of separation point and universal statistic algorithm, two new algorithms were proposed, which were FFT spectrum estimation and discrete Wavelet Transformation algorithm. The above three algorithms were used to analyze the NACA0012 wind tunnel test data. The result demonstrated discrete Wavelet Transformation algorithm was the best of all.Flexible thermal sensor array has been adopted to detect the boundary layer separation point. The sensor array output signals were processed by high speed data acquisition system based DSP, and analyzed by discrete Wavelet Transformation algorithm to determine the location of the separation point. The test data demonstrated the above system can fulfill the dynamic and real-time of the adaptive control system.