Discussion of Experimental Set-Up - Calculate the Cd, Cv and Cc at Different Pressure Heads

Discussion of Experimental Set-up:

        Located at the bottom of the cylindrical tank is the inlet pipe that is connected to the water supply. It fills up the tank and provides the water flow for the orifice. An adjustable overflow pipe is also installed in the tank to control the water level and to serve as basis of the head pressure. The jet flow data can be obtained from the discharge of the orifice plate, which is located at the lower portion of the tank. To get the flow rate, a beaker is placed at the end of the projectile to measure the volume, and the elapsed time is recorded using a stop watch. The needles, which serve as the recording system along with the clipboard, are positioned above the path of the jet to measure the data correctly.

Relation:

        One of the main objectives of the experiment is to calculate the Cd, Cv and Cc at different pressure heads. These coefficients will show the accuracy of the experimental apparatus corresponding to the theoretical concepts. The coefficient of discharge, Cd, is the ratio of the actual discharge to the ideal discharge. It can be calculated by measuring the head, the volumetric flow rate, and the cross sectional area of the orifice. The coefficient of velocity, Cv, is the ratio of the actual velocity to the ideal velocity. It is relates to the x and y distances spanned by the water jet with the head. The coefficient of contraction, Cc, is the ratio of the actual diameter to the ideal diameter of the jet.

        For every trial, the head increases by 5cm. It was observed that the x component of the projectile increases while the y component decreases. Consequently, the speed of jet also increases. The coefficients were computed using the formulas derived. It was shown that the values obtained for Cv was more accurate compared to Cd and Cc. This proves that friction can greatly affect the flow rate of the jet. Other errors can be from the flow rate calculation using beaker and stop watch, as well as the inaccurate positioning of the needles.

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