Air at 20 C flows at a velocity of 2 m/s across a rectangular flat plate . The plate is 25 cm long in the direction of flow and 5 cm wide. It is at a temperature of 160 C. ( a ) What types of boundary layers are on the plate, laminar or turbulent ? (b) What is the boundary layer thickness at a distance 15 cm downstream of the leading edge ? (c) What are the velocity components u and y at a location 15 cm downstream of the leading edge and at the middle of the boundary layer ?

Air at 20 C flows at a velocity of 2 m/s across a rectangular flat plate . The plate is 25 cm long in the direction of flow and 5 cm wide. It is at a temperature of 160 C. ( a ) What types of boundary layers are on the plate, laminar or turbulent ? (b) What is the boundary layer thickness at a distance 15 cm downstream of the leading edge ? (c) What are the velocity components u and y at a location 15 cm downstream of the leading edge and at the middle of the boundary layer ?

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.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.55P

See similar textbooks

Similar questions

Water (T= 10 C, , k=0.644 W/m.C, u = 5.54× 10^-7 m2/s, Pr=3.55), flow over plate 1m x 1m , with velocity 2 m/s. the plate surfące temperature is 90 C. Give the answer for the following |-the flow tyPe 2-total het transfer 3-theavargeheat transfer cafficient 4- Nu ?
Topic: Heat transfer Completely solve and box the final answer. A 20degC water flows to 50cmx60cm flat plate with velocity of 6m/s . The flat plate surface temperature is maintained at 40deg C. The air flows parallel to the 50cm side of the plate. If the kinematic viscosity of water is 78x10-8 m2/s, at what length the flow become turbulent? If the average laminar heat transfer coefficient of water is 7740W/m2 degC, what is the overall heat transfer at the laminar section?
Atmospheric boundary layers can be estimated using turbulent flow approximations over a flat-plate and the velocity profile given for the ‘Turbulent Core’ applies across the entire boundary layer. Assume the wind is blowing at 10 m/s at a height of 80 m above a smooth and flat beach. Air temperature can be assumed to be 20oC. (a) Estimate the shear stress produced by the wind on the beach surface in Pa if the air is at standard sea-level conditions. (b) Determine the wind velocity striking your nose if you are standing and your nose is 170 cm off the ground. (c) Determine the wind velocity striking your nose if you are lying on the beach and your nose is 17 cm off the ground?
(a) What is boundary layer flow and what are the key assumptions used in simple analytical solutions. What are the outputs from simple solutions and to what practical configurations do they apply most closely and why.
(b) In turbulent flows contrast the approaches that are used to represent the velocity profile within the boundary layer and comment on any limitations that each may offer.
Air at 20-C and 1 atm flows over a flat plate at 35 m/s. The plate is 75 cm long and is maintained at 60-C. AJASsuming unit depth in the z direction, calculate the heat transfer from the plate. Calculate the turbulent-boundary-layer thickness at the end of the plate assuming that it develops B) from the leading edge of the plate and C) from the transition point at Recrit =5x105.
Air at standard pressure flows across a flat plate at 3m/s. The temperature surface is 50oC and the surrounding temperature is 20o Consider a point 1m away from the leading edge of the plate. See Table A-15 in Appendix 1 for properties of air. Determine the Reynold’s number and Prandtl number for this flow at the location described above. Determine the local flow boundary layer thickness. Determine the local thermal boundary layer thickness for this flow.
Atmospheric air with free flow velocity U_∞= 30 m/s flows through a circular cylinder at T_∞= 250 K and D = 2.5 cm diameter. The surface of the circular cylinder is kept at a uniform temperature T_w = 350 K.The CD drag coefficient is 1.1. (D=1 cm- 3 cm and U_∞= 10 m/sec 30 m/s)(a) Calculate the average heat transfer coefficient ( h ̅_m,W/m2K)(b) Determine the amount of heat transfer (Q, W) per 1 m length of the cylinder(c) Calculate the drag force (FD, N) acting on the 1 m length of the cylinder FD=0.1 A=0.34 D=2.9 cd=1.2
Atmospheric air with free flow velocity U_∞= 30 m/s flows through a circular cylinder at T_∞= 250 K and D = 2.5 cm diameter. The surface of the circular cylinder is kept at a uniform temperature T_w = 350 K. The CD drag coefficient is 1.1. (D=1 cm- 3 cm and U_∞= 10 m/sec 30 m/s)(a) Calculate the average heat transfer coefficient ( h ̅_m,W/m2K)(b) Determine the amount of heat transfer (Q, W) per 1 m length of the cylinder(c) Calculate the drag force (FD, N) acting on the 1 m length of the cylinder
Air at standard pressure flows across a flat plate at 3m/s. The temperature surface is 50oC and the surrounding temperature is 20o Consider a point 1m away from the leading edge of the plate. See Table A-15 in Appendix 1 for properties of air. Determine the Reynold’s number and Prandtl number for this flow at the location described above. Determine the local flow boundary layer thickness. Determine the local thermal boundary layer thickness for this flow. Find the local Nusselt number. Based on this Nusselt number, what is the local convective heat flux from the plate to the air?
Consider an airflow over the surface of a flat plate with a temperature Ts = 250 °C. At some distance from y the origin, the temperature profile of the airflow is given by the following function: q/A As, Ts T(y) = T, -(T. -T3)exp -u. y a fluido dAs The airflow at atmospheric pressure has a free flow velocity u.. = 0.06 m/s and a temperature T = 15°C. The thermal diffusivity of the fluid is aluid = 3.872E-05 m?/s and its thermal conductivity Afluid = 0.03383 W/(m K). 1. Determine the heat flux over the surface of the plate. q/A = W/m? 2. Determine the convection coefficient of the airflow. h = W/(m² K)
Engine oil at 100°C flows on the top surface of a 1-m-long flat plate maintained at 20°C. The oil’s freestream speed (u infinity) is 0.1 m/s. Find the engine oil properties from the table A.5 A. Evaluate the Reynolds number, local convection coefficient, heat flux and shear stress at the end of the plate (x = L). Is the air flow laminar or turbulent over the plate?B. Evaluate the average convection coefficient, average heat flux, average shear stress and drag force over the plate.