BME Hydraulic Machines 2

Question 1

What is cavitation in a centrifugal pump?

Accepted Answer

Formation and collapse of vapor bubbles due to local pressure drop below vapor pressure

Answer

Cavitation occurs when local pressure falls below the liquid's vapor pressure, causing vapor bubbles that implode violently and damage pump components.

Question 2

The Net Positive Suction Head Available (NPSHA) must be:

Accepted Answer

Greater than NPSHR to prevent cavitation

Answer

NPSHA must exceed NPSHR (required) by a sufficient margin to ensure local pressures never drop to vapor pressure and cavitation does not occur.

Question 3

In a Pelton wheel turbine, the jet of water strikes:

Accepted Answer

Cup-shaped buckets tangentially

Answer

A Pelton wheel is an impulse turbine where high-velocity jets strike cup-shaped (double-hemispherical) buckets tangentially, converting kinetic energy to mechanical work.

Question 4

The specific speed of a turbine is used to:

Accepted Answer

Classify turbine type and predict performance similarity

Answer

Specific speed is a dimensionless (or dimensional) similarity parameter that classifies turbine types and allows performance prediction across geometrically similar machines.

Question 5

Which hydraulic turbine is best suited for high head and low flow rate conditions?

Accepted Answer

Pelton wheel

Answer

The Pelton wheel operates efficiently under very high heads (hundreds to thousands of meters) with relatively low volumetric flow rates.

BME - Bachelor of Mechanical Engineering Practice Test

BME - Bachelor of Mechanical Engineering Practice Test

BME Hydraulic Machines 2