Chemical Engineering - MCQ Practice Questions

The Reynolds number for a fluid flow is defined as the ratio of inertial forces to viscous forces. For a pipe flow with diameter 0.05 m, velocity 2 m/s, and kinematic viscosity 1.0×10⁻⁶ m²/s, calculate the Reynolds number.

Which of the following statements about laminar flow in a circular pipe is correct?

A fluid flows through a horizontal pipe of diameter 0.1 m at a velocity of 3 m/s. If the pipe suddenly contracts to 0.05 m diameter, what is the velocity in the contracted section (assuming incompressible flow)?

The friction factor 'f' in the Darcy-Weisbach equation depends on Reynolds number and relative roughness. For laminar flow (Re < 2300), friction factor is given by:

Water flows through a pipe at 15°C (ρ = 999 kg/m³, μ = 1.139×10⁻³ Pa·s). If flow rate is 0.05 m³/s through a 0.1 m diameter pipe, is the flow laminar or turbulent?

In open channel flow, the Froude number (Fr) determines the type of flow. For a rectangular channel with depth 0.5 m and velocity 1.5 m/s, calculate the Froude number (g = 9.81 m/s²).

For turbulent flow in smooth pipes, which equation is commonly used to estimate friction factor?

The minor losses in pipe fittings are expressed as K×(V²/2g) where K is the loss coefficient. For a 90° elbow with Re = 50,000, typical K value is:

In a centrifugal pump, the head developed is given by Euler's pump equation. If impeller outlet tangential velocity is 20 m/s and inlet tangential velocity is 4 m/s, calculate theoretical head (g = 9.81 m/s²):

A manometer shows a pressure difference of 50 mm of mercury (ρ_Hg = 13,600 kg/m³). What is the equivalent pressure difference in Pa?

In boundary layer theory on a flat plate, the displacement thickness δ* represents:

For compressible flow through a nozzle, if pressure drops significantly and reaches sonic conditions, the Mach number at that point is:

A hydraulic jump occurs in open channel flow when:

The Moody diagram is used to determine friction factor for pipe flow. It shows that friction factor increases with:

For a fluid flowing over a submerged object, the drag force is given by F_D = ($\frac{1}{2}$)ρV²AC_D. If velocity doubles and drag coefficient remains constant, drag force increases by a factor of:

In computational fluid dynamics (CFD), the Courant number (Co = U×Δt/Δx) is important for numerical stability. For explicit schemes, the Courant number should be:

For a reciprocating pump with bore diameter 0.08 m, stroke length 0.15 m, and operating at 60 RPM with 90% volumetric efficiency, the discharge is approximately:

In a convergent-divergent (de Laval) nozzle for compressible flow, the pressure reaches minimum (maximum acceleration) at:

The Navier-Stokes equation for incompressible flow includes terms for pressure gradient, viscous forces, and inertial forces. Under creeping flow conditions (Re → 0), which term becomes negligible?

For a horizontal pipe with diameter variation from D₁ to D₂, if pressure difference is ΔP and ignoring losses, the velocity ratio V₁/V₂ is: