Constant velocity air inlet controller

The experimental implementation of a microprocessor-based controller to adjust the width of hinged baffled slot inlets is described. The system was designed to utilize a velocity sensor which output a digital pulse train proportional to the air velocity as the feedback mechanism to the controller. The controller adjusted the slot width as necessary to maintain a setpoint velocity within a specified deadband. Results, in terms of system response to a step change in either air flow rate (such as additional fans turning on), or to a step change in setpoint velocity, are presented. An analysis of this nonlinear control system resulted in the characterization of the system response in terms of a linear, second-order model. To illustrate a means for further improvement in controller response, the design of a lead compensator cascaded to the original controller is discussed. This method of control is believed to have several advantages compared with current air inlet controllers.