What is the primary function of a centrifugal pump?
A Regulate flow rate
B Increase pressure
C Increase water velocity
D Convert mechanical energy into fluid energy
A centrifugal pump works by converting mechanical energy into fluid energy using an impeller that accelerates the fluid. This allows the pump to generate flow and pressure in systems requiring fluid movement.
What is the primary cause of cavitation in hydraulic systems?
A High flow rate
B High water temperature
C Low fluid pressure
D High fluid viscosity
Cavitation occurs when the pressure in a fluid drops below its vapor pressure, causing vapor bubbles to form. These bubbles can collapse violently, damaging pump impellers and other components in hydraulic systems.
What type of turbine is used in high-head, low-flow applications?
A Turgo turbine
B Pelton wheel
C Francis turbine
D Kaplan turbine
The Pelton wheel is an impulse turbine ideal for high-head, low-flow conditions. It uses high-velocity water jets to strike the turbine’s buckets, converting kinetic energy into mechanical energy efficiently in these conditions.
What is the purpose of a surge tank in a hydraulic system?
A Absorb pressure fluctuations
B Store energy
C Regulate flow rate
D Increase water flow
Surge tanks are used to absorb sudden pressure changes (like water hammer) in a hydraulic system. They help stabilize pressure and prevent damage to pipelines and equipment from rapid flow fluctuations.
What is the primary characteristic of a reaction turbine?
A Blades are fixed and do not move
B Water flows tangentially to the blades
C Both pressure and kinetic energy contribute to energy conversion
D Water is directed through nozzles
A reaction turbine uses both the pressure and kinetic energy of the fluid to generate mechanical energy. Water flows through the blades, where both pressure and velocity changes result in turbine rotation, unlike impulse turbines.
What happens during a hydraulic jump in an open channel?
A Water velocity decreases, and depth increases
B Pressure increases
C Water depth decreases
D Water velocity increases
A hydraulic jump occurs when high-velocity water abruptly slows down, resulting in an increase in water depth and turbulence. This energy dissipation process is commonly used in open channels to control flow.
How does a fluid coupling work in mechanical systems?
A Smooths power transmission by using fluid
B Transmits power using mechanical gears
C Regulates fluid flow rate
D Absorbs fluid pressure
A fluid coupling uses fluid to transmit power between rotating shafts. It helps absorb shocks and reduces mechanical stress by providing smooth acceleration and deceleration, which improves the overall lifespan of the system.
What does “specific speed” refer to in turbines?
A Speed of water entering the turbine
B Turbine’s rotational speed
C Speed of the fluid leaving the turbine
D Dimensionless number that helps classify turbines
Specific speed is a dimensionless parameter used to classify turbines based on their performance characteristics, helping in the selection of the appropriate turbine type for a given flow and head condition.
What is the effect of head loss in a hydraulic system?
A Decreases pressure and flow
B Increases efficiency
C Increases pressure
D Increases fluid velocity
Head loss in a hydraulic system is caused by friction or turbulence and results in a decrease in pressure and flow rate. It reduces system efficiency and increases the energy required to maintain fluid movement.
What does a velocity diagram represent in a turbine?
A Energy conversion efficiency
B Changes in water velocity through the turbine
C Water pressure distribution
D Fluid density changes
A velocity diagram helps visualize and analyze the velocity of fluid as it enters and exits the turbine. This analysis aids in understanding the turbine’s energy conversion efficiency and optimizing its performance.
What is the main characteristic of a centrifugal pump?
A Operates at a constant speed
B Adjustable blades
C Flow rate varies with pressure
D Positive displacement
A centrifugal pump’s flow rate changes with the pressure it is working against. Unlike positive displacement pumps, centrifugal pumps do not provide a fixed volume per cycle, and their performance depends on the system’s pressure.
What is the primary cause of water hammer in pipelines?
A High water temperature
B Increased fluid velocity
C Sudden valve closure
D Fluid viscosity
Water hammer is caused by the sudden closure of a valve, leading to a rapid change in flow velocity. This generates a pressure surge or shockwave that can cause significant damage to pipes, fittings, and equipment.
What does a hydraulic structure like a dam typically control?
A Water flow, level, and pressure
B Fluid velocity
C Fluid density
D Water flow, level, and pressure
Hydraulic structures such as dams are designed to control water flow, maintain desired water levels, and manage pressure. They regulate water for various purposes, including flood control, power generation, and irrigation.
What is the primary purpose of a spillway in a dam?
A Store water
B Release excess water safely
C Increase power generation
D Regulate flow rates
A spillway is a structure built to release excess water from a dam in a controlled manner. This prevents the dam from overflowing, protects the structure, and ensures safe downstream flow during periods of heavy rain.
What does a surge tank prevent in a hydraulic system?
A Water hammer
B Energy dissipation
C Fluid evaporation
D Water quality loss
Surge tanks help prevent water hammer by absorbing rapid pressure surges that occur due to sudden changes in flow. They protect pipes, valves, and pumps from damage caused by these high‐pressure waves.