Calculate the total friction drag on a flat plate of length 3 m and width 1.2 m in a uniform stream of water of velocity 1.2 m/s, when transition occurs at a distance (x) from the leading edge. Also, calculate the boundary layer thickness and the shape factor at transition. (1.14*103 N.s/m²; Pwater = 1000 kg/m³) Assuming the following boundary layer velocity profiles: for laminar part ; 7--2²-(4) = U. Note: You may use the following: For laminar boundary layer: ra μU B 8 and 24 for turbulent part For turbulent boundary layer: r = 0.023 pU μ PU 8

Calculate the total friction drag on a flat plate of length 3 m and width 1.2 m in a uniform stream of water of velocity 1.2 m/s, when transition occurs at a distance (x) from the leading edge. Also, calculate the boundary layer thickness and the shape factor at transition. (1.14*103 N.s/m²; Pwater = 1000 kg/m³) Assuming the following boundary layer velocity profiles: for laminar part ; 7--2²-(4) = U. Note: You may use the following: For laminar boundary layer: ra μU B 8 and 24 for turbulent part For turbulent boundary layer: r = 0.023 pU μ PU 8

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.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.24P: Engine oil at 100C flows over and parallel to a flat surface at a velocity of 3 m/s. Calculate the...

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Engine oil at 100C flows over and parallel to a flat surface at a velocity of 3 m/s. Calculate the thickness of the hydrodynamic boundary layer at a distance 0.3 m from the leading edge of the surface.
Fairings are attached to the front and back of a cylindrical body to make it look more streamlined. What is the effect of this modification on the (a) friction drag, (b) pressure drag, and (c) total drag? Assume the Reynolds number is high enough so that the flow is turbulent for both cases.
The airfoil section of the wing of the British Spitfire of World War II fame is an NACA 2213 at the wing root, tapering to an NACA 2205 at the wing tip. The root chord is 8.33 ft. The measured profile drag coefficient of the NACA 2213 airfoil is 0.006 at a Reynolds number of 9 × 106. Consider the Spitfire cruising at an altitude of 19000 ft. Assume that μ varies as the square root of temperature. At this velocity and altitude, assuming completely turbulent flow, estimate the skin-friction drag coefficient for the NACA 2213 airfoil, and compare this with the total profile drag coefficient. Calculate the percentage of the profile drag coefficient that is due to pressure drag. (Round the final answer to three decimal places.) The skin-friction drag coefficient for the NACA 2213 airfoil is .
Name some applications in which a large drag is desired.
One dimension of a rectangular flat plate is twice the other. Air at uniform speed flows parallel to the plate, and a laminar boundary layer forms on both sides of the plate. Which orientation—long dimension parallel to the wind (Fig. a or short dimension parallel to the wind (Figb —has the higher drag? Explain.
A commercial airplane has a total mass of 70,000 kg and a wing planform area of 150 m2. The plane has a cruising speed of 558 km/h and a cruising altitude of 12,000 m, where the air density is 0.312 kg/m3. The plane has double-slotted flaps for use during takeoff and landing, but it cruises with all flaps retracted. Assuming the lift and the drag characteristics of the wings can be approximated by NACA 23012 , determine (a) the minimum safe speed for takeoff and landing with and without extending the flaps, (b) the angle of attack to cruise steadily at the cruising altitude, and (c) the power that needs to be supplied to provide enough thrust to overcome wing drag.
a)What is the impact of increasing Reynolds number on skin friction and pressure drags over an airfoil? What can be happened for separation in this case? b) What is an adverse pressure gradient and where does it occur on an airfoil (show that on a sketch)? c) Why lift-to-drag ratio is an important parameter for an aircraft? d)How can changing in altitude affect the aircraft power required, PR? Show thatmathematically and graphically?
A) How does an airfoil generate lift? Hint: Support your answer by a sketch. B) Compare between the laminar and turbulent boundary layers? Hint: Show their velocity profiles in a sketch and highlight the main differences. C) Which boundary layer is preferable when it comes to separation? Why? D) Why do golf balls have dimples? Hint: Support your answer by a sketch. E) What will happen to the critical Reynolds number for each of the following cases: i- Pressure gradient is made more adverse. ii- Surface roughness is decreased. iii-Free-stream turbulence is increased.
13.94. A body travels through 60° standard air at 60 mph, and 5.5 hp is required to maintain this speed. If the projected area is 13.5 ft2 , find the drag coefficient. Ans. 0.28
The airfoil section of the wing of the British Spitfire of World War II fame is an NACA 2213 at the wing root, tapering to an NACA 2205 at the wing tip. The root chord is 8.33 ft. The measured profile drag coefficient of the NACA 2213 airfoil is 0.006 at a Reynolds number of 9 × 106. Consider the Spitfire cruising at an altitude of 19000 ft. Assume that μ varies as the square root of temperature. At what velocity is it flying for the root chord Reynolds number to be 9 × 106? (Round the final answer to the nearest whole number.) The velocity at which the spitfire is flying for the root chord Reynolds number to be 9 × 106 is ..........ft/s.
Solve Parts A-C and label Them QUESTION: Suppose you buy a 3 x 7-ft sheet of plywood and put it on your roof rack. You drive home at 45 mi/h. Part A - If the board is perfectly aligned with the airflow, how thick is the boundary layer at the end of the board? Part B - Estimate the drag on the sheet of plywood if the boundary layer remains laminar? Part C - Estimate the drag on the sheet of plywood if the boundary layer is turbulent (assume the wood is smooth) and compare the result to that of the laminar boundary layer case. HINT - 3 X 7-ft sheet of plywood and put it on your roof rack. You drive home at 45 mi/h.
A 17,000-kg tractor-trailer rig has a frontal area of 9.2 m2, a drag coefficient of 0.96, a rolling resistance coefficient of 0.05 (multiplying the weight of a vehicle by the rolling resistance coefficient gives the rolling resistance), a bearing friction resistance of 350 N, and a maximum speed of 110 km/h on a level road during steady cruising in calm weather with an air density of 1.25 kg/m3. Now a fairing is installed to the front of the rig to suppress separation and to streamline the flow to the top surface, and the drag coefficient is reduced to 0.76. Determine the maximum speed of the rig with the fairing.