Question:

(a) Water is to be supplied to the Pelton wheel of a hydroelectric power plant by a pipe of uniform

diameter, 400 m long, from a reservoir whose surface is 200 m vertically above the nozzles. The

required volume flow of water to the Pelton wheel is 30 m3

/s. If the pipe skin friction loss is not to

exceed 10% of the available head and f 0.0075, determine the minimum pipe diameter.

(b) You are required to select a suitable pipe diameter from the available range of stock sizes to

satisfy the criteria given. The range of diameters (m) available are 1.6, 1.8, 2.0, 2.2, 2.4, 2.6,

and 2.8. For the diameter you have selected, determine

(i) the friction head loss in the pipe;

(ii) the nozzle exit velocity assuming no friction losses occur in the nozzle and the water

leaves the nozzle at atmospheric pressure;

(iii) the total power developed by the turbine assuming that its efficiency is 75% based upon

the energy available at turbine inlet.

3. A multi-jet Pelton turbine with a wheel 1.47 m diameter, operates under an effective head of

200 m at nozzle inlet and uses 4 m3

/s of water. Tests have proved that the wheel efficiency is

88% and the velocity coefficient of each nozzle is 0.99. Assuming that the turbine operates at

a blade speed to jet speed ratio of 0.47, determine

(i) the wheel rotational speed;

(ii) the power output and the power specific speed;

(iii) the bucket friction coefficient given that the relative flow is deflected 165;

(iv) the required number of nozzles if the ratio of the jet diameter-mean diameter of the wheel is

limited to a maximum value of 0.113.

4. A four-jet Pelton turbine is supplied by a reservoir whose surface is at an elevation of 500 m

above the nozzles of the turbine. The water flows through a single pipe 600 m long, 0.75 m diameter, with a friction coefficient f 0.0075. Each nozzle provides a jet 75 mm diameter and the

nozzle velocity coefficient KN 0.98. The jets impinge on the buckets of the wheel at a radius of

0.65 m and are deflected (relative to the wheel) through an angle of 160. Fluid friction within

the buckets reduces the relative velocity by 15%. The blade speed-jet speed ratio ? 0.48 and

the mechanical efficiency of the turbine is 98%. Calculate, using an iterative process, the loss of

head in the pipeline and, hence, determine for the turbine

(i) the speed of rotation;

(ii) the overall efficiency (based on the effective head);

(iii) the power output;

(iv) the percentage of the energy available at turbine inlet that is lost as kinetic energy at turbine

Captial Project Funds a. Are not required by GASB b. Are required to be used to account for capital asset acquisitions financed from general obligation bond proceeds, and also whenever legally or contractually required C. Do not record Other Financing Sources and Other Financing Uses d. Are frequently used tby SLGs o account for major general government capital lease acquisitions