LABORATARY MANUAL FM & HM LAB MECHANICAL WORKSHOP DEPARTMENT OF MECHANICAL ENGINEERING
CLOSED CIRCUIT BERNOULLI’S APPARATUS AIM OF THE EXPERIMENT To verify Bernoulli’s equation with the help of closed circuit Bernoulli’s apparatus. APPARATUS REQUIRED a) Bernoulli’s apparatus. b) Stop watch DESCRIPTION OF EQUIPMENT This unit consists of supply chamber and interlinking experimental duct kept horizontally with transparent sides, made out of Perspex sheets for the purpose of absorbing the flow. The interlinking duct is smoothly varying in cross-section, so that the velocity of flow changes gradually for the purpose of experiments with minimum of frictional loss due to turbulence. Piezometer glass tubes are provided at suitable intervals along the duct for the measurement of pressure head at measurement of rate of flow. A special fitting with cork is provided for discharging colored liquid at the inlet of the duct for visualization of streamline flow. Suitable size of sump is provided to store adequate water for doing experiment. This is arranged with flow space of the main unit. Pour adequate water in the sump leaving 25mm at the top. 0.25 HP single phase mono block pump set is rigidly fixed in the unit, which operates on single phase ac supply and pump the adequate water to the supply chamber through proper piping system. The pump should be primed before starting. THEORY According to Bernoulli’s theorem, in continuous liquid flow, total head along the flow is the same i.e. datum head, pressure head, velocity head is constant at different points. ZA+ (PA/w) + (VA2/2g) = ZB+ (PB/w) + (VB2/2g) (PA/w) + (VA2/2g) = (PB/w) + (VB2/2g) PROCEDURE i) ii) iii) iv) The sump is filled with water up to ¾ of the tank level. The machine is kept main switch on. The pump is started. The pressure head is measured directly from the piezometric tubes and scales at seven experimental points, along the experimental duct at suitable intervals.
v) The area of cross-section is taken on each one of these seven tubes fitted to the duct so that the velocity of flow is calculated at each of these points. The flow rate, which is discharge, is obtained from the outlet tank with the help of a stopwatch by measuring the time and height of rise of water in the outlet tank. The velocity head is calculated for each seven experimental points. vi) vii) PRECAUTION- Before starting the pump ensure that the delivery valve is in closed condition. OBSERVATIONS Sl Section of duct No Inlet Section of duct flow rate 50mm×20mm 1 Section of duct flow rate45mm ×20mm 2 Section of duct flow rate 40mm ×20mm 3 Section of duct flow rate 35mm×20mm 4 Section of duct flow rate 30mm×20mm 5 Section of duct flow rate 25mm×20mm 6 Section of duct flow rate 20mm×20mm 7 Section of duct flow rate 15mm×20mm Outlet Section of duct flow rate 10mm×20mm Pressure Velocity Total head head head (cm) (cm) (cm)
TABULATION Sec. No Time in Sec Actual Discharge 1 2 3 4 5 6 7 CONCLUSIONS Area of Velocity section head(m) Velocity Pressure Total Remarks Head(m) Head(m)