S III. Experimental Setup The Experiment rig consists of the following components 1. Wind tunnel The experiment was carries out in a suction type wind tunnel with maximum speed of 1200 RPM in aerodynamics lab. It consisted of a convergent zone which is fitted with a honey-comb entry followed by a mesh to ensure the flow with less vorticity and help in making the flow parallel and uniform. The convergent zone was followed by a test section, divergent zone and fan at the end with the required control systems setup. Probes are placed in the wind tunnel to acquire necessary flow parameters. 2. Multi-tube Manometer The multi-tube manometer with ethanol as the manometric liquid consists of a series of tubes to measure the pressure in the wind tunnel, which are connected parallel to a reservoir which is open to ambient. The setup was given a tilt of 45 0 to magnify pressure readings to reduce reading errors. 3. Cylinder-Pitot rake setup An airfoil model with uniform cross section was placed in the test section of the wind tunnel. Drag force on it is calculated in this method with the help of pressures recorded by the pitot rake. The pitot rake consists of a few pitot tubes arranged in parallel to one another and fitted after the cylinder so the effect of the profile of aerofoil is known. The set up used in the lab is given in the following figure. IV. Procedure • Check the connections of probes with wind tunnel and the multi-tube manometer. • Ensure the surface where the manometer is placed in level to the ground using the spirit level. Note down the angle of tilt given to the manometer. • Open the cap of the ethanol reservoir. Move the reservoir up and down to ensure that there is no blockage in the pipes. • Record the atmospheric temperature and pressure readings of the lab.
5 of 7 Aerodynamics Lab Report, IIST • Power on the motor drive and increase the rpm quasi-statically to a value of 600 RPM. • Note down the pressure tapping readings connected to the pitot rake, start and end of convergent zone of the wind tunnel.
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