| 摘要 |
An impeller-driven turbomachinery for use in centrifugal and mixed flow pump overcomes operational difficulties, such as flow separation and generation of surge at low flow rates, often encountered in similar machines of the conventional design. The turbomachinery is provided with variable-angle inlet guide vane and variable-angle diffuser vanes, and the diffuser section is constructed according to a fluid dynamic principle, and the vanes having a wing shape are distributed tangentially so that the diffuser section acts as a centrifugal diffuser. A convenient operational parameter, chosen from such variables as input current to drive motor, rotational speed or torque of the drive motor, inlet/exit pressures, and fluid velocity, is monitored during the operation by means of sensors strategically attached to parts of the operating system. Real time changes in the operating parameter is measured and the setting angle of the inlet guide vane is adjusted in accordance with a predetermined relation between inlet flow volume rates and flow angle of the fluid exiting from the impeller so as to maintain the fluctuations in the monitored operating parameter below a threshold value. If the targeted head value is not produced under this adjustment, the setting angle of the diffuser vanes can also be adjusted based on real time measurements of other operational parameters. If this adjustment fails to produce the targeted head value, then the rotational speed of the impeller can be adjusted to operate the system while avoiding surge and other problems encountered at flow rates. The proposed turbomachinery and method of operations are highly costeffective because the control methodology is based on theoretical analysis of the flow pattern which is verified by trials, and it is not necessary to determine the operating characteristics of each production lot of fluid machines, thus saving the cost of software development for different machines. |
