The Field Structure. Arm Rotation Sink Hydrogen Bubble Flow Measurement And Fluid Dynamic Parameters Of Control Device

Aiming at the research of low speed experimental fluid dynamics and flow control experiments in electromagnetic hydrodynamics (EMHD),the experiment system of rotating annular tank was developed based on DSP control platform for the investigation of flow around cylinder with flow field structure analysis and hydrodynamic force measurement. The experimental system contained rotating arm, rotating annular tank equipment to produce flow field with high stability,electrical control device,flow field structure display device,hydrodynamic force measurement system and DSP control platform.According to the needs of the experiment,the rotating arm,rotating annular tank equipment were designed and manufactured.Two adjustable square waves were generated by DSP control system to control the voltage of the platinum wire(diameter 17μm) to generate the hydrogen bubble and scattering slice lighting source to light the flow field region, contributing to visualize and analyze the flow field structure.The voltage signal generated by the drag and lift force sensor was processed by filtration,reshaping,and magnification, and then exported to the A/D channel of the DSP control system to obtain the hydrodynamic force (such as drag and lift force) of the object placed in the flow field.The experimental system of rotating arm and flow field visualization device of hydrogen bubble in the rotating annular tank and hydrodynamic force measurement device, by utilizing TMS320F2812(DSP chip) control platform,can be used both in the Lagrangian coordinates and Eulerian coordinates to carried out experimental research of fluid dynamics and flow control. The adjustable square wave signals(1 Hz～255 Hz) generated by the I/O channel of the DSP are connected with a solid state relay and supplied the regulated power,so that the time line and density of the hydrogen bubble and the strength of lighting source could be adjusted flexibly.The hydrodynamic force is converted by the A/D module of the DSP system.The period of analog-to-digital conversion is 0.1 s in the paper and the sampling length can be adjusted at the range of 1～2000,which facilitate the analysis of rules of the relevant hydrodynamic force parameters.The tests and experiments proved that the rotating arm and rotating annular tank experiment system with flow field visualization and hydrodynamic force measurement meet the needs of relevant experimental hydrodynamics. In according to some research projects,the experiments of flow around cylinder have been fulfilled mainly with the experiment system of rotating annular tank.The rotating annular tank system shows good performance in relevant experiments and some valuable research progress are obtained.