Description : Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone. (A) Laminar (B) Transition (C) Both 'a' & 'b' (D) Highly turbulent
Last Answer : (D) Highly turbulent
Description : Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. (A) Grashoff (B) Reynolds (C) Both 'a' & 'b' (D) Prandtl & Grashoff
Last Answer : (D) Prandtl & Grashoff
Description : Maximum heat transfer rate is achieved in __________ flow. (A) Co-current (B) Counter-current (C) Turbulent (D) Laminar
Last Answer : (C) Turbulen
Description : Fanning equation is given by (∆P/ρ) = 4f (L/D) (v 2 /2gc ). It is applicable to __________ region flow. (A) Transition (B) Laminar (C) Turbulent (D) Both (B) and (C)
Last Answer : (D) Both (B) and (C)
Description : Pick out the correct statement pertaining to transition/ entrance length in fluid flow. (A) The length of entrance region of pipe, in which full development of fluid flow takes place such that velocity profile does not change ... pipe of diameter 'd' is equal to 50 D (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of (A) Grashoff number (B) Grashoff number & Reynolds number (C) Reynolds number (D) Grashoff number & Prandtl number
Last Answer : Option D
Description : A straight line is obtained on plotting reciprocal of filtration rate vs. the volume of filtrate for __________ flow of filtrate. (A) Compressible cakes and laminar (B) Incompressible cake and laminar (C) Compressible cake and turbulent (D) Incompressible cake and turbulent
Last Answer : (B) Incompressible cake and laminar
Description : Transition from laminar flow to turbulent flow is aided by the (A) Surface roughness and curvature (i.e. sharp corners) (B) Vibration (C) Pressure gradient and the compressibility of the flowing medium (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : When the pipe Reynold's number is 6000, the flow is generally (A) Viscous (B) Laminar (C) Turbulent (D) Transition
Last Answer : (C) Turbulent
Description : In turbulent flow, a rough pipe has the same friction factor as a smooth pipe (A) In the zone of complete turbulence (B) When the roughness projections are much smaller than the thickness of ... ) Everywhere in the transition zone (D) When the friction factor is independent of the Reynold's number
Last Answer : (B) When the roughness projections are much smaller than the thickness of the laminar film
Description : Transition from laminar flow to turbulent flow in fluid flow through a pipe does not depend upon the (A) Length of the pipe (B) Diameter of the pipe (C) Density of the fluid (D) Velocity of the fluid
Last Answer : (A) Length of the pipe
Description : The Graetz number is concerned with the (A) Mass transfer between a gas and a liquid (B) Absorption with chemical reaction (C) Heat transfer in turbulent flow (D) Heat transfer in laminar flow
Last Answer : (D) Heat transfer in laminar flow
Description : Dittus-Boelter equation used for the determination of heat transfer coefficient is valid (A) For fluids in laminar flow (B) For fluids in turbulent flow (C) When Grashoff number is very important (D) For liquid metals
Last Answer : (B) For fluids in turbulent flow
Description : Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low ... Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers
Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension
Description : For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus-Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of (A) 1 (B) 1.74 (C) 6.1 (D) 37
Last Answer : (C) 6.1
Description : In turbulent flow, the (A) Fluid particles move in an orderly manner (B) Momentum transfer is on molecular scale only (C) Shear stress is caused more effectively by cohesion than momentum transfer (D) Shear stresses are generally larger than in a similar laminar flow
Last Answer : (D) Shear stresses are generally larger than in a similar laminar flow
Description : In case of a plate and frame filter press, filtrate flow through the cake follows __________ flow. (A) Plug (B) Turbulent (C) Laminar (D) None of these
Last Answer : (C) Laminar
Description : Transition length for turbulent flow in smooth pipe is equal to __________ times the pipe diameter. (A) 0.5 (B) 5 (C) 50 (D) 500
Last Answer : (C) 50
Description : The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by __________ times, when the number of tube passes is increased to 8. (A) 2 0.8 (B) 4 0.8 (C) 4 0.4 (D) 2 0.4
Last Answer : (B) 4 0.8
Description : A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer coefficient for turbulent flow conditions is proportional to (A) d 0.8 (B) d -0.2 (C) d -1 (D) d -1.8
Last Answer : (B) d -0.2
Description : Bernoulli's equation describes the (A) Mechanical energy balance in potential flow (B) Kinetic energy balance in laminar flow (C) Mechanical energy balance in turbulent flow (D) Mechanical energy balance in boundary layer
Last Answer : (A) Mechanical energy balance in potential flow
Description : Pick out the correct statement. (A) A forced vortex occurs when fluid rotates as a solid about an axis (B) In laminar flow, Newton's law of viscosity does not apply (C) A free vortex occurs, when fluid rotates as a solid (D) In turbulent flow, there are neither cross-currents nor eddies
Last Answer : (A) A forced vortex occurs when fluid rotates as a solid about an axis
Description : Pick out the wrong statement. (A) The form drag is dependent upon the occurrence of a wake (B) The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent ... of viscosity (D) Existence of the boundary layer in fluid flow is because of viscosity of the fluid
Last Answer : (C) An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity
Description : f = 16/NRe , is valid for (A) Turbulent flow (B) Laminar flow through an open channel (C) Steady flow (D) None of these
Last Answer : (D) None of these
Description : The distribution of shear stress in a stream of fluid in a circular tube is (A) Linear with radius for turbulent flow only (B) Linear with radius for laminar flow only (C) Linear with radius for both laminar & turbulent flow (D) Parabolic with radius for both laminar & turbulent flow
Last Answer : (C) Linear with radius for both laminar & turbulent flow
Description : Pick out the wrong statement. (A) A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocit (B) Newton's law of viscosity is not applicable to the ... types of bearings (D) Rise of water in capillary tubes reduces with the increasing diameter of capillary tubes
Last Answer : (B) Newton's law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution
Description : The laminar boundary layer thickness in zero pressure gradient flow over a flat plate along the x-direction varies as x0.5 while the thickness of turbulent boundary layer varies as (where, x = distance from the leading edge) (A) x1.5 (B) x0.8 (C) x-1.5 (D) x-0.8
Last Answer : (B) x0.8
Description : Nusselt number is related to the Reynolds number (Re) in turbulent & laminar flow respectively as (A) Re0.5, Re0.8 (B) Re0.8, Re-0.5 (C) Re0.8, Re0.5 (D) Re-0.8, Re0.5
Last Answer : (C) Re0.8, Re0.5
Description : Nusselt number is related to Grashoff number (Gr) in turbulent & laminar flow respectively, in respect of free convection over a vertical flat plate as (A) Gr0.25, Gr (B) Gr0.25, Gr0.33 (C) Gr, Gr0.25 (D) Gr0.33, Gr0.25
Last Answer : Option A
Description : A flow in which the viscosity of fluid is dominating over the inertia force is called (A) Steady flow (B) Unsteady flow (C) Laminar flow (D) Turbulent flow
Last Answer : Answer: Option C
Description : General energy equation holds for (A) Steady flow (B) Turbulent flow (C) Laminar flow (D) Non-uniform flow
Last Answer : Answer: Option D
Description : A large Reynold number is indication of (A) Smooth and streamline flow (B) Laminar flow (C) Steady flow (D) Highly turbulent flow
Description : The velocity at which the flow changes from laminar flow to turbulent flow is called (A) Critical velocity (B) Velocity of approach (C) Sub-sonic velocity (D) Super-sonic velocity
Last Answer : Answer: Option A
Description : The flow in a pipe is neither laminar nor turbulent when Reynold number is (A) Less than 2000 (B) Between 2000 and 2800 (C) More than 2800 (D) None of these
Last Answer : Answer: Option B
Description : Define : (i) Laminar flow (ii) Turbulent flow
Last Answer : Laminar flow: - 1. Laminar flow occurs when the fluid flows in infinitesimal parallel layers with no disruption between them. For laminar flow Reynolds number Re < 2300 OR 2. The flow in which ... such a way that its velocity changes irregularly, such type of flow is known as turbulent flow.
Description : Compare i) Steady and uniform flow ii) Laminar and turbulent flow
Last Answer : Steady flow:- The flow is said to be steady when the flow characteristics, such as velocity, pressure, density and temperature do not change with time. Water flowing through a tap at a constant rate is an ... called as turbulent flow. e.g. The flow of river at the time of flood is turbulent flow.
Description : Define laminar flow and turbulent flow.
Last Answer : Laminar flow : When a fluid flowing through the pipe at different speeds (fast at center and slow at edges), and the fluid particles move in layers with one layer sliding over the adjacent ... successive cross sections, then this flow is called as turbulent flow. Reynolds no is greater than 4000
Description : The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are (A) Re.Gz (B) Nu, Pr (C) Nu, Pr, Re (D) Nu, Gz
Last Answer : (D) Nu, Gz
Description : For a laminar flow of fluid in a circular tube, 'h1 ' is the convective heat transfer co-efficient at velocity 'V1 '. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is (A) 1.26 h1 (B) 0.794 h1 (C) 0.574 h1 (D) 1.741 h1
Last Answer : (B) 0.794 h1
Description : The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re 0.8 , where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient ... pipe diameter (D) as (A) D-1.8 (B) D-0.2 (C) D0.2 (D) D1.8
Last Answer : (B) D-0.2
Description : All analogy equations connecting friction factor and heat transfer coefficient apply only to (A) Wall or skin friction (B) Form friction (C) Both (A) and (B) (D) Turbulent flow
Last Answer : (A) Wall or skin friction
Description : Transition length for a turbulent fluid entering into a pipe is around __________ times the pipe diameter. (A) 5 (B) 50 (C) 500 (D) 5000
Last Answer : (B) 50
Description : What is the ratio of total kinetic energy of fluid passing per second to the value obtained on the basis of average velocity (for laminar flow through a circular pipe)? (A) 0.5 (B) 1 (C) 1.5 (D) 2
Last Answer : (D) 2
Description : Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is (A) > 10 (B) < 10 (C) > 100 (D) < 100
Last Answer : (B) < 10
Description : For the Stoke's law to be valid in the case of a falling sphere in a fluid, the (A) Reynolds number (based on sphere diameter) should be < 1 (B) Flow around the sphere should be in turbulent region (C) Sphere must be metallic (D) Fluid density should be constant
Last Answer : (C) Sphere must be metallic
Description : Combustion in compression ignition engine is a. homogeneous b. heterogeneous c. laminar d. turbulent
Last Answer : ANSWER b. heterogeneous
Description : Even though heat transfer co-efficient in boiling liquids is large, use of fins is advantageous, when the entire surface is exposed to __________ boiling. (A) Film (B) Nucleate (C) Transition (D) All modes of
Description : Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In ... layers over a flat plate are of equal thickness, if Schmidt number is equal to unity
Last Answer : (C) For Laminar flow over a plate of length L, the local mass transfer coefficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s
Description : Pick out the wrong statement. (A) Momentum transfer in laminar flow results from velocity gradient (B) A fluid in equilibrium is not free from shear stress (C) The viscosity of a non-Newtonian fluid is a function of temperature only (D) Both (B) and (C)
Description : Momentum transfer in laminar flow of fluids results due to the (A) Viscosity (B) Density (C) Velocity gradient (D) None of these
Last Answer : (C) Velocity gradient