What is the primary cause of capillary action in fluids?
A Cohesive and adhesive forces
B Gravitational force
C Viscous forces
D Surface tension
Capillary action is caused by the interplay between cohesive forces (between liquid molecules) and adhesive forces (between liquid and solid surfaces). This allows liquids to flow in narrow spaces without external forces, such as water rising in a thin tube.
What is the primary purpose of a stagnation point in fluid flow?
A Measure pressure
B Measure velocity
C Identify zero velocity
D Measure flow rate
A stagnation point is a point in fluid flow where the velocity of the fluid is zero. It occurs where the flow impinges on a solid surface or divides around an object, and it is used to analyze pressure distribution.
What is the primary cause of hydraulic jump in open channel flow?
A Sudden increase in velocity
B Sudden decrease in velocity
C Change in channel slope
D Change in fluid density
A hydraulic jump occurs when a high velocity, supercritical flow transitions to a low velocity, subcritical flow. This results in a sudden rise in the water surface and energy dissipation, commonly seen in spillways and sluice gates.
What is the primary purpose of a Moody chart?
A Measure flow rate
B Calculate pressure drop
C Determine friction factor
D Determine viscosity
A Moody chart is used to determine the Darcy Weisbach friction factor for pipe flow. It relates the friction factor to the Reynolds number and relative roughness, helping engineers calculate pressure losses in pipes.
What is the primary cause of flow instability in pipes?
A Sudden valve closure
B High Reynolds number
C Low Reynolds number
D Change in pipe diameter
Flow instability in pipes is often caused by sudden changes in flow conditions, such as valve closure or pump failure. This can lead to water hammer, pressure surges, and vibrations in the pipeline.
What is the primary purpose of a Francis turbine?
A Measure flow rate
B Generate electricity
C Increase pressure
D Reduce velocity
A Francis turbine is a type of hydraulic turbine used to convert the energy of flowing water into mechanical energy, which is then used to generate electricity. It is suitable for medium head applications.
What is the primary cause of energy loss in open channel flow?
A Gravity
B Surface tension
C Friction
D Viscosity
Energy loss in open channel flow is primarily due to friction between the flowing water and the channel bed and walls. This is quantified using the Manning equation or Chezy equation.
What is the primary purpose of a vortex tube in fluid systems?
A Reduce temperature
B Separate fluids
C Measure flow rate
D Increase pressure
A vortex tube is a device that separates compressed air into hot and cold streams using centrifugal force. It is used for cooling applications in industrial processes.
What is the primary cause of flow choking in compressible flow?
A Subsonic velocity
B Sonic velocity
C High pressure
D Low temperature
Flow choking occurs in compressible flow when the fluid velocity reaches the speed of sound (sonic velocity). At this point, the flow cannot accelerate further, and the mass flow rate becomes maximum.
What is the primary purpose of a Kaplan turbine?
A Measure flow rate
B Increase pressure
C Reduce velocity
D Generate electricity
A Kaplan turbine is a type of hydraulic turbine used for low head, high flow applications. It converts the energy of flowing water into mechanical energy, which is then used to generate electricity.
What is the primary cause of flow separation in boundary layers?
A Adverse pressure gradient
B Increase in velocity
C Decrease in viscosity
D Increase in temperature
Flow separation occurs when the fluid flow slows down due to an adverse pressure gradient, causing the boundary layer to detach from the surface. This leads to the formation of eddies and vortices.
What is the primary purpose of a Pelton wheel?
A Measure flow rate
B Increase pressure
C Reduce velocity
D Generate electricity
A Pelton wheel is a type of impulse turbine used for high head, low flow applications. It converts the kinetic energy of water jets into mechanical energy, which is then used to generate electricity.
What is the primary cause of flow uniformity in pipes?
A Laminar flow
B High Reynolds number
C Turbulent flow
D Low Reynolds number
Turbulent flow in pipes ensures better mixing and uniformity of velocity across the cross section. This is due to the chaotic motion of fluid particles, which reduces velocity gradients.
What is the primary purpose of a flow nozzle?
A Increase pressure
B Measure flow rate
C Reduce velocity
D Measure viscosity
A flow nozzle is a device used to measure the flow rate of a fluid by creating a pressure drop across the nozzle. It is commonly used in high velocity flow applications.
What is the primary cause of flow transition in pipes?
A Reynolds number
B Pressure gradient
C Temperature change
D Viscosity change
Flow transition in pipes depends on the Reynolds number. For 2000 < Re < 4000, the flow is transitional, meaning it can switch between laminar and turbulent depending on disturbances.