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Pharos University ME 259 Fluid Mechanics for Electrical Students Revision for Mid-Term Exam. Dr. A. Shibl. Manometer Example Determine the pressure at point A in the figure below if h 1 = 0.2 m and h 2 = 0.3 m. Use water = 1000 kg/m 3 . Solution: P 2 = P 1 + Hg gh 2
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Pharos UniversityME 259 Fluid Mechanics for Electrical Students Revision for Mid-Term Exam Dr. A. Shibl
Manometer Example Determine the pressure at point A in the figure below if h1 = 0.2 m and h2 = 0.3 m. Use water = 1000 kg/m3. Solution: P2 = P1 + Hggh2 But P1 = Patm(open to atmosphere) ==>P1 = 0 (gauge) P2 = Hggh2 P3 = PA + waterg(h1+h2) We know that P2 = P3 (same horizontal level) Thus Hggh2 = PA + waterg(h1+h2) PA = Hggh2 - waterg(h1+h2) PA = 13.54x1000x9.81x0.3 – 1000x9.81x(0.2+0.3) PA = 39, 848 - 4905 PA = 34.9 kPa (gauge) Points to be selected: 1 – at the open end of the manometer 2 – at the right leg of the manometer 3 – same level with point 2 but at left leg of the manometer 4 – same level as point A Pressure at the points: P1=Patm P2 = P3 P4 = PA
Static Force Example • A rectangular gate of dimension 1 m by 4 m is held in place by a stop block at B. This block exerts a horizontal force of 40 kN and a vertical force of 0 kN. The gate is pin-connected at A, and the weight of the gate is 2 kN. Find the depth h of the water.
Continuity Example • Water flows steadily through a nozzle. The nozzle diameter at the inlet is 5 cm, and the diameter at the exit is 3cm. The average velocity at the inlet is 4 m/s. What is the average velocity at the exit? • V1 A1 = V2 A2
Water moving through Venture nozzle reaches a low pressure at section 1. Nozzle dimensions are d1 = 3 mm, d2 = 9 mm, and h = 150 mm. Determine the minimum possible water speed (V2) at the exit of the nozzle so that fluid will be drawn up the suction tube.
A water jet with a velocity of 30 m/s impacts on a splitter plate so that 1/4 of the water is deflected toward the bottom and 3/4 toward the top. The angle of the plate is 45o. Find the force required to hold the plate stationary. Neglect the weight of the plate and water, and neglect friction.