JNTUH
JNTUH B.Tech II FLUID MECHANICS AND HYDRAULIC MACHINES Previous Question Paper (April/May - 2023 - R16)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
PART – A
Define mass density and specific weight.
Answer
Mass density (ρ) is defined as the mass of a fluid per unit volume. It is expressed as ρ = m/V, with SI units of kg/m³.
Specific weight (w or γ) is defined as the weight of a fluid per unit volume. It is expressed as w = ρg, where g is the acceleration due to gravity, with SI units of N/m³.
What is specific gravity? How is it related to density?
Answer
Specific gravity, also known as relative density, is defined as the ratio of the density of a given fluid to the density of a standard fluid at a specified temperature. For liquids, the standard fluid is typically water at 4°C, while for gases, it is usually air at standard atmospheric pressure and temperature.
The relationship between specific gravity (S) and density (ρ) is expressed by the formula:
where ρ is the density of the fluid and ρ_standard is the density of the reference substance. Since it is a ratio of two densities, specific gravity is a dimensionless quantity.
What do you understand by hydrostatic law?
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Differentiate between rotational and irrotational flow.
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Write down the expression for capillary fall.
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Define Bernoulli’s equation with assumptions.
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What is the need for priming in pump?
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Explain vapor pressure and cavitation.
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What is the function of impeller?
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What does indicator diagram indicates?
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PART – B
Calculate specific weight, density and specific gravity of two liters of a liquid which weigh 15 N.
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The capillary rise in the glass tube is not to exceed 0.2mm of water. Determine its minimum size given that surface tension of water in contact with air is 0.0725 N/m.
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Explain centre of pressure and total pressure, also derive an expression for it when the plate is imaged vertically.
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Define pressure. Obtain an expression for the pressure intensity at a point in a fluid.
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Water is flowing through a pipe of 5 cm diameter under a pressure of 29.43 N/cm² and with mean velocity of 2 m/sec. Find the total head or total energy/unit weight of water at a cross section which is 5m above datum line.
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Write Euler’s equation of motion along a streamline and integrate it to obtain Bernoulli’s equation. State all assumptions made.
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An oil of viscosity 0.1 N/m² and relative density 0.9 is flowing through a circular pipe of diameter 50mm and of length 300mm. The rate of flow of fluid through the pipe is 3.5 litre/sec. Find the pressure drop in a length of 300m.
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What are the losses experienced by a fluid when it is passing through a pipe?
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Discuss the following: i) The concept of the boundary layer with reference to fluid motion over a flat plate ii) Phenomenon of separation for flow over carved surfaces.
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Find the loss of head when a pipe of diameter 200 mm is suddenly enlarged to a diameter of 400 mm. The rate of flow of water through the pipe is 250 litres/sec.
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What do you mean by pipes in series and pipes in parallel arrangements and what is its applications?
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Crude oil of kinematic viscosity 0.4 stoke is flowing through a pipe of diameter 300 mm at the rate of 300 litres/sec. Find the head lost due to friction for a length of 50 m of the pipe.
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Draw main characteristic curves of hydraulic turbine.
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A Pelton wheel is to be designed for the following specifications. Shaft power = 11772 kW, Head = 380 m, speed = 750 rpm, overall efficiency = 86%, jet diameter not to exceed 1/6 of wheel diameter. Determine i) Wheel diameter ii) Number of jets required iii) Diameter of jet. Coefficient of velocity = 0.985, speed ratio = 0.45.
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With the help of neat diagram explain the construction and working of a radial flow reaction turbine.
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A jet of water of diameter 10cm strikes a flat plate normally with a velocity of 15m/sec. The plate is moving with a velocity of 6m/sec in the direction of jet and away from it. Find i) force exerted by the jet on the plate ii) work done by jet on plate/sec. iii) power of the jet.
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The internal and external diameters of the impeller of a centrifugal pump are 200mm and 400 mm respectively. The pump is running at 1200 rpm the vane angles of the impeller at inlet and outlet are 20° and 30° respectively. The water enters the impeller radially and velocity of flow is constant. Determine the work done by the impeller/unit weight of water.
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Write about (i) various efficiencies of centrifugal pump (ii) characteristic curves of centrifugal pump.
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What is a reciprocating pump? Describe the principle and working of a reciprocating pump with a neat sketch.
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A centrifugal pump is to discharge 0.118 m³/sec at a speed of 1450 rpm against a head of 25m. The impeller diameter is 250mm, its width at outlet is 50mm and manometric efficiency is 75%. Determine the vane angle at the outer periphery of the impeller.
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