What is the primary cause of lift force on an aircraft wing?
A Surface roughness
B Fluid density
C Shape of wing
D Flow velocity
Lift is primarily caused by the difference in air pressure above and below the wing, which is influenced by the wing’s shape (airfoil). The curvature of the top surface causes air to move faster, reducing pressure above the wing and generating lift.
What happens to the density of a fluid in compressible flow?
A Constant
B Decreases with pressure
C Fluctuates
D Increases with pressure
In compressible flow, particularly with gases, the fluid’s density changes significantly with variations in pressure and temperature. As pressure increases, the density of the fluid typically increases, and vice versa.
In which type of fluid flow does the velocity remain the same across any cross‐section?
A Steady flow
B Turbulent flow
C Incompressible flow
D Laminar flow
In steady flow, the fluid velocity at each point does not change with time. This is contrasted with unsteady flow, where velocity at a given point fluctuates over time.
What is the primary factor affecting the drag force on an object moving through a fluid?
A Fluid temperature
B Object shape
C Fluid pressure
D Fluid density
Drag force is significantly influenced by the shape of the object. A streamlined object experiences less drag because the fluid flows smoothly around it, whereas irregular shapes cause turbulence, leading to higher drag.
How does the velocity profile of a fluid change when the flow is laminar in a pipe?
A Linear
B Uniform
C Parabolic
D Exponential
In laminar flow within a pipe, the velocity profile is parabolic, with the maximum velocity at the center of the pipe and decreasing near the walls due to friction.
What type of flow is characterized by irregular, chaotic fluid motion?
A Steady flow
B Laminar flow
C Compressible flow
D Turbulent flow
Turbulent flow occurs when the fluid moves chaotically, characterized by eddies and swirls. It occurs at high velocities or with low-viscosity fluids and is more energy‐dissipating compared to laminar flow.
How does the pressure in an incompressible fluid change as the flow speed increases, according to Bernoulli’s principle?
A Increases
B Decreases
C Fluctuates
D Stays constant
According to Bernoulli’s principle, as the velocity of an incompressible fluid increases, its pressure decreases. This inverse relationship helps maintain energy conservation within the fluid system.
What is the main difference between compressible and incompressible flow?
A Velocity
B Fluid temperature
C Density changes
D Fluid pressure
In compressible flow, the fluid density changes significantly with pressure and temperature, as seen in gases. In incompressible flow, typically with liquids, the density remains constant even when pressure or temperature changes.
In a fluid flow system, which factor primarily determines the Reynolds number?
A Flow velocity
B Fluid viscosity
C Pipe diameter
D Fluid density
The Reynolds number is determined by the ratio of inertial forces to viscous forces. It depends on the flow velocity, fluid density, viscosity, and pipe diameter. A high Reynolds number indicates turbulent flow, while a low number indicates laminar flow.
What is the effect of temperature on the viscosity of most fluids?
A No effect
B Increases viscosity
C Decreases viscosity
D Varies with pressure
For most fluids, an increase in temperature decreases viscosity. The fluid particles gain more kinetic energy, allowing them to move past each other more easily, reducing internal friction.
What is the primary purpose of using a fluid flow meter?
A Measure viscosity
B Measure pressure
C Measure temperature
D Measure flow rate
A flow meter is used to measure the flow rate of a fluid, typically in pipes or ducts. It helps monitor and control the fluid’s movement, ensuring efficient system operation and correct distribution.
In which flow regime does the velocity of fluid vary unpredictably and create vortices?
A Turbulent flow
B Laminar flow
C Viscous flow
D Steady flow
In turbulent flow, the fluid’s velocity is irregular and unpredictable, with the formation of vortices and eddies. This leads to chaotic fluid movement and high energy dissipation compared to laminar flow.
What happens to the pressure drop in a pipe as fluid viscosity increases?
A Remains constant
B Increases
C Depends on velocity
D Decreases
As viscosity increases, the fluid’s resistance to flow increases, leading to a higher pressure drop. More energy is required to move the fluid, especially in pipes with smaller diameters or longer lengths.
What type of flow occurs when the velocity of fluid does not change across its cross‐section?
A Steady flow
B Turbulent flow
C Uniform flow
D Laminar flow
Uniform flow occurs when the velocity of the fluid is the same at every point across any cross‐section of the flow. This is a key feature of certain types of idealized flow, such as in some ducts and pipes.
What is the primary effect of reducing the pipe diameter in a flow system?
A Increases velocity
B Reduces drag
C Increases pressure
D Decreases velocity
According to the continuity equation, if the pipe diameter is reduced, the velocity of an incompressible fluid increases in order to maintain a constant flow rate. This happens because the product of area and velocity must remain constant.