Hydrodynamic And Thermal Boundary Layers MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on Hydrodynamic And Thermal Boundary Layers, a fundamental topic in the field of Heat Transfer. Whether you're preparing for competitive exams, honing your problem-solving skills, or simply looking to enhance your abilities in this field, our Hydrodynamic And Thermal Boundary Layers MCQs are designed to help you grasp the core concepts and excel in solving problems.

In this section, you'll find a wide range of Hydrodynamic And Thermal Boundary Layers mcq questions that explore various aspects of Hydrodynamic And Thermal Boundary Layers problems. Each MCQ is crafted to challenge your understanding of Hydrodynamic And Thermal Boundary Layers principles, enabling you to refine your problem-solving techniques. Whether you're a student aiming to ace Heat Transfer tests, a job seeker preparing for interviews, or someone simply interested in sharpening their skills, our Hydrodynamic And Thermal Boundary Layers MCQs are your pathway to success in mastering this essential Heat Transfer topic.

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Hydrodynamic And Thermal Boundary Layers MCQs | Page 5 of 5

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Q41.
Boundary layer thickness is given by

a.

δ = 5.64 x/ (Re) ½

b.

δ = 5.64 x/ (Re) ½

c.

δ = 6.64 x/ (Re) ½

d.

δ = 7.74 x/ (Re) ½

Discuss
Answer: (b).δ = 5.64 x/ (Re) ½
Q42.
Air at 25 degree Celsius flows over a flat surface with a sharp leading edge at 1.5 m/s. Find the value of Reynolds number. For air at 25 degree Celsius, kinematic viscosity = 15.53* 10n¯⁶ m²/s

a.

38694

b.

12846

c.

48294

d.

76386

Discuss
Answer: (c).48294
Q43.
A plate 0.3 m long is placed at zero angle of incidence in a stream of 15 degree Celsius water moving at 1 m/s. Find out the maximum value of the normal component of velocity at thr trailing edge of the plate. For water at 15 degree Celsius

p = 998.9 kg /m³
µ = 415.85 * 10¯² kg/hr m

a.

1.6885 * 10¯² m/s

b.

1.6885 * 10¯³ m/s

c.

1.6885 * 10¯⁴ m/s

d.

1.6885 * 10¯⁵ m/s

Discuss
Answer: (b).1.6885 * 10¯³ m/s
Q44.
Consider the diagram given below and identify the correct option

a.

The velocity gradient is zero everywhere

b.

The velocity profile changes at every instant of time

c.

Boundary layers from the pipe walls meet the pipe anywhere

d.

Thickness of the boundary layer is limited to the pipe radius

Discuss
Answer: (d).Thickness of the boundary layer is limited to the pipe radius
Q45.
A two pass surface condenser is required to handle the exhaust from a turbine developing 15 MW with specific steam consumption of 5 kg/k W h. The quality of exhaust steam is 0.9, the condenser vacuum is 66 cm of mercury while the bar meter reads 76 cm of mercury. The condenser tubes are 28 mm inside diameter, 4 mm thick and water flows through tubes with a speed of 3 m/s and inlet temperature 20 degree Celsius. All the steam is condensed, the condensate is saturated water and temperature of cooling water at exit is 5 degree Celsius less than the condensate temperature. Assuming that overall coefficient of heat transfer is 4 k W/m² degree, determine the mass of cooling water circulated.

a.

746.13 kg/s

b.

646.13 kg/s

c.

546.13 kg/s

d.

446.13 kg/s

Discuss
Answer: (d).446.13 kg/s
Q46.
A single pass shell and tube heat exchanger, consisting of a bundle of 100 tubes (inner diameter 25 mm and thickness 2 mm) is used for heating 28 kg/s of water from 25 degree Celsius to 75 degree Celsius with the help of a steam condensing at atmospheric pressure on the shell side with condensing heat transfer coefficient 5000 W/m² degree. Make calculation for overall heat transfer coefficient based on the inner area. Take fouling factor on the water side to be 0.002 m² degree/W per tube and neglect effect of fouling factor on the shell side and thermal resistance of the tube wall

a.

647.46 W/m² degree

b.

747.46 W/m² degree

c.

847.46 W/m² degree

d.

947.46 W/m² degree

Discuss
Answer: (c).847.46 W/m² degree
Q47.
The lubricating oil for a large industrial gas turbine engine is cooled in a counter flow, concentric tube heat exchanger. The cooling water flows through the inner tube ( diameter = 25 mm) with inlet temperature 25 degree celsius and mass flow rate 0.2 kg/s. The oil flows through the annulus (diameter = 50 mm) with mass flow rate 0.125 kg/s and its temperature at entry and exit are 90 degree Celsius and 60 degree Celsius. Find outlet temperature of cooling water.

a.

14.58 degree celsius

b.

24.58 degree celsius

c.

34.58 degree celsius

d.

44.58 degree celsius

Discuss
Answer: (c).34.58 degree celsius
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