1. In flow over a surface, velocity and temperature profiles are of the forms u(y)=Ay+By²-Cy³ and T(y)=D+Ey+Fy²+Gy³ where the coefficients A through G are constants. Obtain expressions for the friction coefficient Cf and the convection coefficient h in terms of u∞, T∞, and appropriate profile coefficients and fluid properties. Answer: h = -krE D T∞

1. In flow over a surface, velocity and temperature profiles are of the forms u(y)=Ay+By²-Cy³ and T(y)=D+Ey+Fy²+Gy³ where the coefficients A through G are constants. Obtain expressions for the friction coefficient Cf and the convection coefficient h in terms of u∞, T∞, and appropriate profile coefficients and fluid properties. Answer: h = -krE D T∞

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.35P

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1. In flow over a surface, velocity and temperature profiles are of the forms u(y)=Ay+By²-Cy³ and T(y)=D+Ey+Fy²+Gy³ where the coefficients A through G are constants. Obtain expressions for the friction coefficient Cf and the convection coefficient h in terms of u∞, T∞, and appropriate profile coefficients and fluid properties. Answer: h= -k[E D To
Q2) In flow over a surface, velocity and temperature profiles are of the forms u(y) = Ay + By² + Cy3 and T(y) = D+ Ey + Fy? - Gy3 where the coefficients A through G are constants. Obtain expressions for the friction coefficient C, and the convection coefficient h in terms of uo, To, and appropriate profile coefficients and fluid properties. Q3) Water at a temperature of T = 25°C flows over one of the surfaces of a steel wall (AISI 1010) whose temperature is Ts1 = 40°C. The wall is 0.35 m thick, and its other surface temperature is Ts,2 = 100°C. For steady state conditions what is the convection coefficient associated with the water flow? What is the temperature gradient in the wall and in the water that is in contact with the wall? Sketch the temperature distribution in the wall and in the adjoining water.
Please answer and explain why each statement must be true or may not be true.
Cooling water for a power plant is stored in a pond 900 m in length and 400 m wide. A dry wind at 300 K blows in a horizontal direction parallel to the 900 m side of the pond at a velocity of 2 m/s. The cooling water is at 300 K. Known the air dynamic viscosity v= 1.67 x10m?/s.; the Re transition from laminar flow to turbulent flow is 500,000; and the saturated water vapor pressure at 300 K is 3580 Pa; gas constant R= 8.3144 J/mole.K. 1.) At what position across the pond is the air flow no longer laminar? Would it reasonable to assume that the mean gas-film mass transfer coefficient for water vapor in air is dominated by turbulent flow mass transfer? 2.) As part of an engineering analysis to predict the evaporation rate of water from the pond, determine the mean gas film mass transfer co-efficient. 3.) Calculate the rate of water evaporation from the pond.
What are the physical and quantitative evidence of turbulence in fluid flow?
Air flows inside a tube 60 mm in diameter (d) and 2.1 m long (l) at a velocity w = 5 m/sec. Find the heat-transfer coefficient α if the mean air temperature tf = 100oC. Note: Write your answer in space provided without the unit (the answer is in kcal/m2-hr-oC, one decimal places)
7-2 Air and water flow at 0.08 kg/s and 0.32 kg/s respectively in a horizontal tube of inside diameter 25 mm. The mean pressure is 9.90 bar (absolute) and the pressure drop across a length of 5 m is 342 FLUID FLOW FOR CHEMICAL ENGINEERS 0.215 bar. What is the value of the friction factor? Assume isothermal conditions. Data: at 9.90 bar, VG = 8.28 x 10-2 m³/kg, V₁ = 1.02 X 10-3 m³/kg.
A thin plate of very large area is placed in a gap of height h with oils of Еxample viscosities u' and u" on the two sides of the plate. The plate is pulled at a constant velocity V. Calculate the position of plate so that : The shear force on the two sides of the plate is equal (i) The force required to drag the plate is minimum. Assume viscous flow and neglect all end effects. SO Position of the plate, y: Thin plate
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A fluid Prandti number Pr=1 at 500K flows over a plate of 2.5 m length, maintained at 300K. The velocity of the fluid is 20m/s. Assuming kinematic viscosity v= 20*10^-6 m2/s. Determine the thermal boundary layer thickness at 0.6 m from the leading edge ?
A plate is cooled by a fluid with Prandtl number Pr >> 1. Surface temperature varies with distance form the leading edge according to where C is constant. For such a fluid it is reasonable to assume that axial velocity within the thermal boundary layer is linear given by u=V% y Determine the local Nusselt number and show that surface heat flux is uniform. Use a third degree polynomial temperature profile and assume laminar boundary layer flow y YA To Vo T₁(x,0)=T +C√√x U -8 &₁ X T₁(x) = T₁ +C√x
2. In a particular application involving airflow over a heated surface, the boundary layer temperature distribution may be approximated as T − Ts T∞ — Ts - = 1 – exp (−Pr- uooy ט where y is the distance normal to the surface and the Prandtl number, Сри Pr = = : 0.7 k is a dimensionless fluid property. If T∞= 400 K, Ts= 300 K, and u∞/v = 5000 m²¹, what is the surface heat flux?