Fluid and Heat Lab Final Preparation

Which of the following is a cause of pressure drop in fluid flow through pipes?

• Friction on internal pipe surface

• Pipe color

• Water temperature only

• Gravity alone

Answer explanation

The correct choice is 'Friction on internal pipe surface' because friction between the fluid and the pipe walls causes energy loss, leading to a pressure drop. Other options do not directly cause pressure drop in fluid flow.

Which instrument uses a constricted throat to measure flow rate based on pressure difference?

• Orifice meter

• Venturimeter

• Pitot tube

• Globe valve

Answer explanation

The Venturimeter uses a constricted throat to create a pressure difference, allowing it to measure flow rate accurately. In contrast, the orifice meter and pitot tube have different designs, and the globe valve is not a flow measurement device.

In turbulent flow, the Darcy friction factor is determined from:

• Reynolds number only

• Pipe diameter

• Moody chart

• Bernoulli equation

Answer explanation

In turbulent flow, the Darcy friction factor is determined using the Moody chart, which relates the friction factor to the Reynolds number and relative roughness of the pipe, making it the correct choice.

The head loss in a rough pipe is generally:

• Zero

• Less than smooth pipe

• Equal to smooth pipe

• Greater than smooth pipe

Answer explanation

The head loss in a rough pipe is greater than in a smooth pipe due to increased friction and turbulence caused by the rough surface, leading to more energy loss as fluid flows through.

Given a pipe of 1 m length and 4.5 mm diameter with ΔP = 500 Pa, ρ = 1000 kg/m³, V = 2 m/s. Calculate frictional head loss.

• 0.051 m

• 0.51 m

• 5.1 m

• 51 m

Answer explanation

The frictional head loss can be calculated using the formula: h_f = ΔP / (ρg). Substituting the values, h_f = 500 / (1000 * 9.81) = 0.051 m. Thus, the correct answer is 0.051 m.

Which fitting has the highest resistance coefficient (K value)?

• Straight pipe

• Ball valve

• 90° elbow

• Smooth bend

Answer explanation

The 90° elbow has the highest resistance coefficient (K value) among the options. This is due to the sharp change in direction it causes, which increases turbulence and resistance compared to the other fittings.

Which expression correctly represents Bernoulli’s equation (in presence of friction)?

• P/ρ + gz + V²/2 = constant

• P/ρ + gz + V²/2 = work/mass + friction loss

• V = Q/A

• ∆P = µQ

Answer explanation

The correct expression for Bernoulli’s equation with friction is P/ρ + gz + V²/2 = work/mass + friction loss, as it accounts for energy losses due to friction, unlike the other options.

What is the primary purpose of using pressure taps at different points along the pipe in the Fluid Friction apparatus?

• To measure flow rate directly

• To determine water density

• To measure head loss due to friction

• To calculate pump efficiency

Answer explanation

The primary purpose of using pressure taps at different points along the pipe is to measure head loss due to friction. This helps in understanding how friction affects fluid flow within the system.

In the experiment, which type of pipe allows evaluation of turbulence effects due to increased surface area?

• Smooth pipe

• Coated pipe

• Rough pipe

• Plastic pipe

Answer explanation

A rough pipe has an increased surface area that enhances turbulence effects, making it ideal for evaluating how surface texture influences fluid flow compared to smooth or coated pipes.

Why is a hydraulics bench integrated into the Fluid Friction setup?

• To store experimental data

• To simulate vacuum pressure

• To provide controlled water flow and drainage

• To detect impurities in water

Answer explanation

The hydraulics bench is integrated into the Fluid Friction setup to provide controlled water flow and drainage, ensuring accurate measurements and consistent experimental conditions.