Orifice and Free Jet Flow

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영문 실험보고서

목차

Summary
Discussion
Conclusions
Notations
Appendices I
Appendices II

본문내용

Summary
The main objective of conducting this experiment is to determine the coefficient of velocity, the coefficient of contraction and the coefficient of discharge for two small orifices.
Based on graph 1, it is shown that at the same head, the jet trajectories are relatively similar to each other regardless of the orifice diameter although the flow rates are different. In short, jet trajectory is only affected by head, H while variations in orifice diameter and flow rate have negligible effects on the jet trajectory.
The values of coefficient of velocity, CV calculated are 0.8929, 0.8249, 0.9391 and 0.9423. As the percentage difference is 5.38%, this difference is acceptable as it is less than the ideal experimental errors which is 10%. Therefore, these values of CV calculated are sufficiently similar to take average which is 0.9248.
The coefficient of discharge is 0.7080 for orifice diameter of 3mm while that for orifice diameter of 6mm is 0.7378. These values are sufficiently similar to take an average as the percentage difference of these values is calculated to be 4.12% which is lower than the ideal experimental percentage of error that is 10%. Thus, the average value of Cd is 0.7229.
Both of the values of Cd and CV are inaccurate as they are higher than the theoretical values. This may be caused by the experimental errors due to the low efficacy of measuring skills.
From the equation CC = Cd/CV, the values of coefficient of contraction, CC calculated are 0.7790 and 0.7843 for orifice diameters of 3mm and 6mm respectively. Besides, the value of CC is also calculated by taking the ratio of the average value of Cd to that of CV, thus giving a value of 0.7817. These values are different from the theoretical values of coefficient of discharge which is ranging from 0.61 to 0.66. This difference may be caused by the unsteady flow of water which will affect the convergence of streamlines approaching the orifice.

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