This report aims to measure the pressure variation and different contributing components of the drag force on a circular cylinder. The devices used in this experiment were a fan, closed-channel venturi-shape pipe, a Pitot tube, circular cylinder with holes of different angles, U-tube manometers and a barometer.
When a fluid is passing through an object, it produces a total force on the object. This force is a combined force of lift and drag forces (Anderson 2007). External flows past objects have been studied extensively because of their many practical applications. For example, airfoils are made into streamline shapes in order to increase the lifts, and at the same time, reducing the aerodynamic drags exerted on the wings. On the other hand, flow past a blunt body, such as a circular cylinder, usually experiences boundary layer separation and very strong flow oscillations in the wake region behind the body (Anderson 2007). In certain Reynolds number range, a periodic flow motion will develop in the wake. In this experiment we will study the pressure variation and different contributing components of the forces on the circular cylinder (Anderson 2007).
In this experiment, circular cylinder with 27 holes was placed behind the Pitot tube. 18 holes were adjusted to 5°, 10°, 15° and so on until 90°, and the next 9 holes were adjusted to 100°, 110° and so on until 180°. All these holes were connected to U-tube manometers which can read the pressure difference between all the holes. Pitot tube was also used to measure the static pressure and the stagnation pressure or usually called the total pressure. Pitot tube was placed in front of the circular cylinder and against flow of fluid which is air in this case. Another device to be used was barometer which is to measure the atmospheric pressure of the room. A fan was placed in front of Pitot tube with Venturi pipe between them to maximise the velocity of the flow. The large...