Fluid Machinery 2022 Question Paper — Government College of Engineeri…

Instructions

• Attempt any five questions selecting at least one from each section.
• Each question carries equal marks

Questions

Section A

• QQ1.. Design a single jet Pelton wheel to develop a power of 600 KW under a head of 180 m while running at 320 rpm. Assume $K_u = 0.45$, $C_v = 0.985$ and overall efficiency = 85%. Calculate the jet diameter, wheel diameter and number of buckets. Give a fully dimensional sketch of the bucket. [15 marks]
• QQ2.. A Kaplan turbine develops 1480 kW under a head of 7 m. The turbine is set 2.5 m above the tailrace level. A vacuum gauge inserted at the turbine outlet records a suction head of 3.1 m. If the hydraulic efficiency is 85%, what would be the efficiency of draft tube having inlet diameter of 3 m? What would be the reading of suction gauge if power developed in reduced to half (740 kW), the head and speed remaining constant. [15 marks]
• QQ3.. An inward flow reaction turbine is required to produce a power of 280 kW at 220 rpm. The effective head on the turbine is 20 m. The inlet diameter is twice the outlet diameter. Assume hydraulic efficiency as 83% and overall efficiency as 80%. The radial velocity is 3.75 m/s and is constant. The ratio of wheel diameter to breadth is 0.1 and 6% of the flow area is blocked by vane thickness. Determine the inlet and outlet diameters, inlet and exit vane angle and guide blade angle at the inlet. Assume radial discharge. [15 marks]
• QQ4.. A one-fifth scale model of a water turbine is tested in a laboratory at $T = 20^{\circ}\text{C}$. The diameter of the model is 8.0 cm, its volume flow rate is $25.5\text{ m}^3/\text{h}$, it spins at 1500 rpm, and it operates with a net head of 15.0 m. At its best efficiency point, it delivers 720 W of shaft power. Calculate the efficiency of the model turbine. What is the most likely kind of turbine being tested? [15 marks]

Section B

• QQ5.. A multi-stage pump is required to feed preheated water to a boiler. The quantity of water to be handled is 40 liter per second against a pressure difference of $3200\text{ kN/m}^2$. The speed of rotation of impeller being 3000 rpm. The specific weight of the preheated water is $960\text{ kg/m}^3$. All impellers are identical and the specific speed per stage is not to exceed 5400. Determine: (i) The minimum number of stages and the head per stage. (ii) The diameter of the impeller assuming a peripheral velocity 0.95 power required to drive the pump, if the overall efficiency is 80% [15 marks]
• QQ6.. A centrifugal blower rotates at 1400 rpm. Air enters into the impeller normal to the blades and exits at an angle of $25^\circ$. The inlet radius is $r_1 = 56.5\text{ cm}$, and the inlet blade width $b_1 = 58.5\text{ cm}$. The outlet radius and the blade width are $r_2 = 12\text{ cm}$ and $b_2 = 4.5\text{ cm}$, respectively. The volume flow rate is $0.22\text{ m}^3/\text{s}$. What is the net head produced by this blower in meters of air? [15 marks]
• QQ7.. A single acting reciprocating pump having a cylinder diameter of 150 mm and stroke of 300 mm. is used to raise the water through a height of 20 m. Its crank rotates at 60 rpm. Find the theoretical power required to run the pump and the theoretical discharge. If actual discharge is 5 liters /s, find the percentage slip. If delivery pipe is 100 mm in diameter and is 15 mm long, find the acceleration head at the beginning of the stroke. [15 marks]
• QQ8.. An axial flow compressor stage has blade root, mean and tip velocities of 150, 200 and 250 m/s respectively. The stage is to be designed for a stagnation temperature rise of 20 K and an axial velocity of 150 m/s, both constant from root to tip. The work done factor is 0.93. Assuming degree of reaction is 0.5 at the mean radius, determine the stage air angles at root mean and tip for a free vortex design where the whirl component of velocity varies inversely with the radius. [15 marks]

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