Design Of Ventilation Control System For Supercavitation Experiment In The Water-Tunnel

Supercavitation technology could reduce about 90% of the drag of water applying on the underwater vehicle. There are main two type supercavities, one is nature supercavity and the other is ventilation supercavity. Because of the two having the same geometrical and dynamical characteristics, and because of the convenience for control the ventilation supercavity, it is an appropriate to study the supercavity via studying the ventilation supercavity.The research presented here devised the ventilation auto-control system for studying the supercavitation in the water tunnel. For finding a method how to attain the stable gas flow, the entire structure of the ventilation equipments has been devised first, and the device for protecting measuring equipments was also devised. Subsequently, the characteristics of the discharge and structure of the govern valve, and the choice of the model number for the govern valve were decided; and the math model of the ventilation was consequently set up, according to it, the digital PID controller was devised. The incremental algorithm was adopted for the algorithm of the controller, and with considering the characteristics of the controller, the algorithm was modified correspondingly. The last step, the hardware and software of the system were both devised. Chip micro-computer AT89S51 was adopted as the core of the hardware devising, and the devising also includes several other parts as input channel and its interface circuit, the output channel and its interface circuit, the interface circuits of the keyboard and monitor, and interface circuit of series communication. The C51 language was adopted as the developing tool, and with it, the sub-layer software of the system was programmed. For ensuring the stability and reliability, the possible environment interferences to the chip microcomputer in the water tunnel experiment were analyzed, and the corresponding suppression method were adopted for the each interference.Via simulation, it is shows that the ventilation control system devised here controls the ventilation discharge well, namely, the control accuracy and response time both satisfy the water tunnel experiment demand; and the ability for real-time displaying and data transferring makes the data monitoring and processing convenient.