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Mechanical Engineering Interview Questions Part – 9


Weingarten This part 9 of the http://trisporttrophies.com/cooking-news/quisque-tristique-ac-sapien-eu-tempor mechanical engineering inteview questions involve the questions and answers of fluid mechanics , power plant engineering, thermodynamics etc. For further information go through these links:


  • Draw the performance curve of centrifugal pump.

Answer:  Click the picture for enlarged view


  • What is cooling tower? Give the Schematic Diagram of cooling tower. What is the difference between cooling towers and condensers?

Answer: Cooling Tower Classification with schematic diagram 

  • What are different types of condensation processes?

Answer: There are mainly two types of condensation processes

  1. Film-wise condensation and
  2. Drop-wise condensation.
  • Draw the diagram of combined cycle power plant. (Combination of Brayton Cycle and Rankin Cycle). Show topping and bottoming cycle in the diagram.

Answer: Please follow the link : Combined Cycle Power Plant with Topping and Bottoming Cycles 

  • What are major and minor head losses in a fluid flow system?

Answer: Major loss is known as the losses that occur in the pipes. Minor losses are head losses which occurs due to bends and elbows (additional parts in the straight pipe system).

  • What is valve? What is the function of butterfly valve?

Answer: Valves are devices which can control the flow of fluid. By controlling means directing and regulating the flow.

In a butter fly valve there is a disc which is hinged to the body. And there is an operator. When operator moves the butterfly valves disc also rotates and creates or blocks passage for the fluid to flow. When the disc is parallel to the flow the liquid passes and when the disc is completely perpendicular the flow also completely stops. Please watch this video for a complete understanding of the butterfly valve.

  • Which type of compressor is used in gas turbine?

Answer: In Gas Turbine cycle three types of compressors are used

These are Axial compressor, centrifugal compressor and mixed flow compressor. Axial compressors are very popular for gas turbine power plants because these are compact and need less space for medium to large thrust gas turbines.

  • What happens in superheating process?

Answer:  In superheating the temperature is increased of the fluid with increasing its pressure.

  • Name some of the flow meters.

Answer: Orifice meters, Venturi meters, Rotameters , nozzles

  • What is a nozzle? What happens in a nozzle?

Answer: nozzle is a device which can control the direction of the fluid along with changing some of its properties. Nozzle is especially used for increasing the velocity of the fluid stream. Generally nozzle is a tapered tube. It is used where high velocity and low pressure is required. It depends on the continuity equation. According to continuity equation if the flow rate is to be remained same the product of area and velocity should remain same on the inlet and outlet. So if area decreases then the velocity increases.

  • What is the expression of a polytropic process?

Answer: Polytrpoic is a thermodynamic process . It follows the relation .

polytropic process expression

  • What is the percentage U238 in nature?

Answer: 99.2745%

  • Relation of absolute pressure, gage pressure and atmospheric pressure.

Answer:  Absolute pressure = Atmospheric Pressure + Gage Pressure

  • Which one has greater efficiency for the same compression ratio? Diesel engine or petrol engine? Explain.

Answer:  For same compression ratio petrol engine has greater efficiency then diesel engine. Otto cycle or petrol engine cycle rejects lesser heat for the same compression ratio than the diesel engine cycle. That’s why it has better efficiency for same compression ratio.

comparison of otto and diesel cycle

More mechanical engineering objective and written questions with answers are coming. Stay tuned.


Basic Mechanical Engineering is a small endeavor for the mechanical engineering students and fresh graduates. All the articles are written by mechanical "rocking" engineers \m/

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