| Scope and method of study. Active flow control offers much promise for improved aircraft performance by delaying stall, increasing lift, reducing drag, enhancing combustion, and decreasing jet noise. The enhanced performance of active control may be achieved through intelligent application of flow field modifiers with the proper characteristics at the proper times and the proper locations. Steady or pulsed blowing may be applied optimally at only those discrete locations where the control system senses it is required to maintain attached flow. The flow control performance of pulsed blowing systems has a strong dependence upon the fluid-acoustic dynamics of the flow control system. Pulsed blowing systems start with a steady flow supply and process it to generate a pulsatile flow with characteristic frequencies of the same order as the frequencies of the flow being controlled. The steady pulsatile flow of internal combustion engine exhaust systems has many similarities to pulsed jet active flow distribution systems. Pulsatile flow in internal combustion engines has been analyzed by Blair (1999). This analysis method is being extended to pulsed jet blowing systems. (Abstract shortened by UMI.)... |
