You are asked by your college crew to estimate the skin friction drag on their eight-seat racing shell. The hull of the shell may be approximated as half a circular cylinder with 457 mm diameter and 7.32 m length. The speed of the shell through the water is 6.71 m/s. Estimate the location of transition from laminar to turbulent flow in the boundary layer on the hull of the shell. Calculate the thickness of the turbulent boundary layer at the rear of the hull. Determine the total skin friction drag on the hull under the given conditions.
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
Fox and McDonald's Introduction to Fluid Mechanics
Additional Engineering Textbook Solutions
Applied Statics and Strength of Materials (6th Edition)
Mechanics of Materials
Automotive Technology: Principles, Diagnosis, and Service (5th Edition)
INTERNATIONAL EDITION---Engineering Mechanics: Statics, 14th edition (SI unit)
Engineering Mechanics: Statics & Dynamics (14th Edition)
DeGarmo's Materials and Processes in Manufacturing
- Estimate the drag force on the fuselage shown below for a cruising speed of 210 m/s at 10,000m. Hint 1: To calculate the drag force split the fuselage into 4 parts: front hemisphere,cylindrical body, vertical stabilizer, back hemisphere. Model the front and back hemispheres as flow over a sphere. For simplicity treat the cylindrical body and vertical stabilizer as flat plates.Hint 2: Use Cd vs Reynolds number graphs for sphere and flat plate. If your Reynolds number is greater/smaller than the Cd vs Reynolds graph range, you can instead use the greatest/smallest number available on the graph.arrow_forwardA helicopter is hovering at an altitude where the density of air is 1.165 kg/m³. The helicopter rotor disc has a diameter of 9 m and is rotating at 466 rpm, with the blades having a chord of 0.16 m. Estimate the drag force in newtons per unit span along an elemental strip at the mid-span of the blade. You may assume the drag coefficient of the blade at the mid-span is 0.025.arrow_forwardTwo large fixed parallel planes are 12 mm apart. The space between the surfaces Example is filled with oil of viscosity 0.972 N.s/m². A flat thin plate 0.25 m² area moves through the oil at a velocity of 0.3 m/s. Calculate the drag force: (1) When the plate is equidistant from both the planes, and (ii) When the thin plate is at a distance of 4 mm from one of the plane surfaces. Fixed parallel plane 6 mm Plate 0.3 m/s F 6 mm 12 mmarrow_forward
- Aircraft flying at an altitude of (3 Km) with a velocity of (100 m/sec). The planform area of the wing is (206 m² ). Find the overall drag force acting on this aircraft if you have the following data :- Aspect ratio= 10, Weight of the aircraft = 7.5 x 105 kg.m/s² Span efficiency factor = 0.95 Wing cross section is NACA 4412 airfoll Drag coefficient = 0.006arrow_forwardCurrent Attempt in Progress In the 1930s, the U.S. Navy operated dirigibles. The largest was the U.S.S. Akron with a length of 785 ft and a maximum diameter of 132 ft. Its maximum speed was 84 mph (123.2 ft/sec). Moving at top speed at 10,000 ft standard atmosphere, estimate the power required in horsepower to overcome the friction drag. Disregard effects of fins and other protrusions. Assume the surface of the dirigible is smooth and the friction drag is that over a flat plate. (Hint: "unwrap" the outer surface of the ship.) W = hparrow_forwardYou are designing an airfoil for a new hobby RC plane. Because of your limited knowledge, you have mistakenly approximated your airfoil as an ellipse with a = 75mm and b = 12mm. Here, “a” is the depth of your wing and “b” is the thickness. Your plane travels through the air at approximately 20mph (8.9m/s). As it does so, skin friction produces a drag-induced heat of 800W on your wind, of length 1m. Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), TInfinity = 25oC a) What is the Reynold’s number? Hint: “D” is taken to be the thickness for an elliptical crosssection. b) What is the Nusselt number? c) What is the convection coefficient? d) What is the average temperature of your wing? Assume an ellipse perimeter of approximately 200mm.arrow_forward
- A ship is 150 m long and has a wetted area of 5000 m2.If it is encrusted with barnacles, the ship requires 7000 hpto overcome friction drag when moving in seawater at 15 kn and 20°C. What is the average roughness of thebarnacles? How fast would the ship move with the samepower if the surface were smooth? Neglect wave drag.arrow_forwardA rotary mixer is constructed from two circular disks as shown. The mixer is rotated at 60 rpm in a large vessel containing a brine solution (SG = 1.1, μbrine=1.07×10-3 Pa-s). Determine the appropriate coefficient of drag using Low Reynolds Drag Coefficient. Neglect the drag on the rods and the motion induced in the liquid. Estimate the minimum torque and power required to drive the mixer. only HANDWRITTEN answer needed ( NOT TYPED)arrow_forwardYou are designing an airfoil for a new hobby RC plane. Because of your limited knowledge, you have mistakenly approximated your airfoil as an ellipse with a = 75mm and b = 12mm. Here, “a” is the depth of your wing and “b” is the thickness. Your plane travels through the air at approximately 20mph (8.9m/s). As it does so, skin friction produces a drag-induced heat of 800W on your wind, of length 1m. Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), TInfinity = 25oC a) What is the average temperature of your wing? Assume an ellipse perimeter of approximately 200mm.arrow_forward
- 3) An advertising sign mounted on the roof of a car is 33 inches tall, 15 inches wide and 54 inches long (airflow direction). The underside of the sign is flush with the top surface of the roof. Take air properties to be: p = 0.075 lbm/ft' and u= 1.22x10 lbm/ft.sec. Used a pressure drag coefficient of 1.2 for the advertisement sign. Calculate the total drag on the sign and the power required to overcome its effect if the car is travelling at a constant speed of a) 12 mph and b) 45 mph. Note: Provide a schematic diagram (sketch) of the problem configuration (if applicable). Every numerical calculation must be preceded by the appropriate equation. Do not forget units & dimensions during your calculations.arrow_forwardAn aeroplane has a rectangular planform wing with a span of 12 m and a chord of 2 m. The aircraft is flying at cruising speed of 62 m/s at an altitude of 3,200 m. Assume that the skin-friction drag on the wing can be approximated by the drag on a flat plate of the same dimensions at 0° incidence. Calculate the skin-friction drag and the maximum boundary layer thickness assuming (i) a completely laminar flow, and (ii) a completely turbulent flow. Assume μ = 1.63.10-5 N s/m², p = 0.89 kg/m³. Then, calculate the skin-friction drag accounting for transition at Recr= 5.105. What would the drag benefit be if transition was delayed to a Reynolds number of 106? What reduction in a propeller engine power would this imply in the cruise condition, assuming a propeller efficiency of 0.88?arrow_forwardb. A smooth thin plate 5 m long and 1 m wide is placed in air streamed moving at 3 m/s with its length parallel with the flow. Analyse the drag force on each side of the plate. The density of the air is 1.2 kg/m3 and the kinematic viscosity is 1.6 x 10-5 m²/s.arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY