BME Hydraulic Machines 3

Question 1

The hydraulic efficiency of a turbine is defined as:

Accepted Answer

Ratio of runner power to water power at inlet

Answer

Hydraulic efficiency is the ratio of the power transferred to the runner to the water power supplied, accounting for hydraulic losses in guide vanes, runner passages, and draft tube.

Question 2

Affinity laws for centrifugal pumps state that at constant impeller diameter, flow rate varies as:

Accepted Answer

Speed ratio to the first power

Answer

The first affinity law states Q ∝ N, so doubling the rotational speed doubles the flow rate when diameter is held constant.

Question 3

A hydraulic accumulator stores energy in the form of:

Accepted Answer

Potential energy of pressurized fluid or elevated weight

Answer

Hydraulic accumulators store energy as pressure potential energy — either via a compressed gas bladder, a weighted piston, or an elevated column of fluid.

Question 4

The volute casing of a centrifugal pump is designed to:

Accepted Answer

Convert kinetic energy of the impeller discharge into pressure energy

Answer

The volute's gradually increasing cross-sectional area decelerates the high-velocity fluid leaving the impeller, converting kinetic energy to pressure (diffusion).

Question 5

Which parameter does NOT change when two geometrically similar pumps operate at homologous conditions?

Accepted Answer

Specific speed

Answer

Specific speed is a similarity parameter that remains constant for geometrically similar pumps operating at homologous (dynamically similar) points on their performance curves.

BME - Bachelor of Mechanical Engineering Practice Test

BME - Bachelor of Mechanical Engineering Practice Test

BME Hydraulic Machines 3