Impact of a Jet

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Abstract The objective of this experiment is to measure the force generated by impact of the jet on vanes of various shapes like flat plate, conical cup and hemispherical cup. Besides that, the results from the experiment have to be compared with the theoretical calculations too.

1.0 Introduction Water turbines are widely used throughout the world to generate power. By allowing fluid under pressure to strike the vanes of a turbine wheel, mechanical work can be produced. Rotational motion is then produced by the force generated as the jet strikes the vanes. One way of producing mechanical work from fluid under pressure is to use the pressure to accelerate the fluid to a high velocity in a jet. The jet is directed on to the vanes of a
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5.0 Error Analysis
The theoretical values given are as below : Flat Plate : 1 Cone : 1.5 Hemisphere : 2
The calculated values based on the experiment are as below : Flat Plate : 1.9 Cone : 2.5 Hemisphere : 3.0
By using the formula, (Estimate-Actual)/Actual x 100% , the percentage errors are as below : Flat Plate : 90% Cone : 66.7% Hemisphere : 50%

The calculations show that the percentage error for each of the vanes is quite huge. This is because there are several errors made during the experiment. One of the errors may be the error made during setting the pointer; the pointer may not precisely set to zero due to parallax error. Another possible error is the error made when recording the time.


There are actually a few suggestions for improving the apparatus. First of all, maintenance need to be done as frequent as possible since the machine has been used for quite some time. This is to ensure that the machine still function accurately. Besides that, the water density might vary due to impurities in the water that might alter the rate of delivery momentum because the density of water is no longer 1000kg/m3. Therefore, cleanliness of water needs to be taken care too. Lastly, the flow rate of water which is not constant causes a big difference in results. The lever is so shaky that it causes the force on the vane to be inaccurate since the distance from the zero position might alter.
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