Design of motor speed control using LabVIEW for air-flow control in wind tunnels

Wind tunnels are used in aerodynamic and heat transfer research to analyze various effects on solid objects when air is forced on to them. This is done using a powerful fan or by a blower. These wind tunnels are equipped with suitable sensors for sensing various parameters like pressure variation, calculating the aerodynamic forces and other fluid flow characteristics. In present work, velocity of air in wind tunnel is controlled by adjusting the fan speed. The fan speed is controlled by varying the voltage supplied to the motor using DAC0808. DAC0808 converts the digital value to analog voltage. The digital value is obtained by considering the set point given (required RPM) by the user through LabVIEW graphical interface. This work describes in detail the user interface developed in LabVIEW that can be used in applications where variable speed required can be attained using a GUI based control.