On a cruise ship, passengers complain about the amount of smoke that becomes entrained behind the cylindrical smoke stack. You have been hired to study the flow pattern around the stack, and have decided to use a 1:15 scale model of the 15-ft smoke stack. What range of wind tunnel speeds could you use if the ship speed for which the problem occurs is 12 to 24 knots?
Want to see the full answer?
Check out a sample textbook solutionChapter 7 Solutions
Fox and McDonald's Introduction to Fluid Mechanics
Additional Engineering Textbook Solutions
Automotive Technology: Principles, Diagnosis, And Service (6th Edition) (halderman Automotive Series)
Thinking Like an Engineer: An Active Learning Approach (3rd Edition)
Mechanics of Materials
Statics and Mechanics of Materials (5th Edition)
Applied Fluid Mechanics (7th Edition)
Engineering Mechanics: Statics & Dynamics (14th Edition)
- Some students want to visualize flow over a spinning baseball. Their fluids laboratory has a nice water tunnel into which they can inject multicolored dye streaklines, so they decide to test a spinning baseball in the water tunnel. Similarity requires that they match both the Rey n olds number and the Strouhal number between their model test and the actual baseball that moves through the air at 90 mi/h and spins at 300 rpm. Both the air and the water are at 68°F. At what speed should they run the water in the water tunnel, and at what rpm should they spin their baseball?arrow_forwardA student team is to design a submarine for a design competition. The overall length of the prototype submarine is 4.85 m. The prototype submarine is expected to moves through freshwater in the lake at 0.440 m/s. The student team builds a one-fifth scale model to test in their university's wind tunnel. Calculate the wind tunnel air speed in order to achieve similarity with the prototype submarine. For water at T= 15 °C and atmospheric pressure, the density is p = 999.1 kg/m³ and the dynamic viscosity is µ = 1.138 x 10³ kg/m-s. For air in the wind tunnel at T= 25 °C and atmospheric pressure, the density is p= 1.184 kg/m³ and the dynamic viscosity is µ = 1.849 x 10-$ kg/m's.arrow_forwardA student wants to estimate drag force on a golf ball of diameter D moving in air at a speed of U at atmospheric conditions. The student has access to a wind-tunnel and develops a replica of the ball that is 5 times smaller in diameter sets the wind speed 5 times larger than the actual golf ball. Compared to the force on the replica, the estimated drag force on the actual golf ball will bearrow_forward
- A student needs to measure the drag on a prototype of characteristic length d, moving at velocity U, in air at sea-level conditions. She constructs a model of characteristic length dm such that the ratio d,/dm drag under dynamically similar conditions in sea-level air. The student claims that the drag force on the prototype will be = a factor f. She then measures the model identical to that of the model. Is her claim correct? Explain, showing your work (no credit for just guessing).arrow_forwardA 1:7 scale model simulates the operation of alarge turbine that is to generate 200 kW with a flowrate of 1.5 m3/s.What flow rate should be used inthe model, and what power output is expected?(a) Water at the same temperature is used in bothmodel and prototype.(b) The model water is at 25°C and the prototypewater is at 10°C.arrow_forwardWe want to predict the drag force on a remote-control airplane as it flies through air having a density of 1.21 kg/m³ and a viscosity of 1.76x10- Pa-s. The airplane's fuselage has a diameter of 200 mm and the airplane will fly through air at a speed of 32 m/s. A model of the airplane's fuselage will be tested in a pressurized wind tunnel. The diameter of the model is 75 mm and the density and viscosity of the air in the wind tunnel are 3.00 kg/m³ and 1.82× 10-5 Pa-s, respectively. a) The diameter of the airplane's fuselage will be used to define the Reynolds number Re, for the flow around the fuselage. Compute the Reynolds number for the flow around the airplane's fuselage (answer: Re, = 4.40x 10'). b) Find the speed of the air that should be used to test a model of the fuselage in the wind tunnel to correctly model dynamic conditions (answer: 35.6 m/s). c) The model is tested in the wind tunnel at four speeds that bracket the speed computed above. The measured drag forces on the…arrow_forward
- Inside a ship building R&D center, a model of a ship was to be put under experimental analysis, for estimating its wave drag. If the speed the actual full scale ship is 1 m/s, then at what speed must be model must be tested?arrow_forwardIn the design and development competition in a University, a team of students has planned to develop a prototype submarine with 6.5 meter length that would travel fully submerged at X m/s speed in a fresh lake water. The team has designed a model which has one-sixth of a prototype size to test in the university wind tunnel to study the effect of various parameters, such as drag force on the prototype (Figure Q2). Considering the necessary assumptions (a) determine the speed of the wind the team has to blow into the tunnel in order to achieve similarity. (b) With all the same conditions the team change their mind and want to develop a smaller size of model to save money and time. Targeting the maximum acceptable speed of the air blown not to exceed 125 m/s to avoid compressibility of air, what should be the minimum length of the model? (c) What will happen to the length of the model if the temperature of the blowing wind increases as a result of the season change? Discuss the reason.arrow_forwardA 1:20 scaled-down model of a hydrofoil is tested in a water channel, at a velocity of 0.179 m/s. At this velocity, a drag force of 2.2 N is measured. Determine the drag force of the original hydrofoil, at a velocity of 0.8 m/s.arrow_forward
- A blimp is designed to move in air at C at 7 m/s. If a 1:20 scale model is tested in water at 20 "C, what should the water velocity be? If the measured water drag on the model is 3.2kN, calculate the drag on the prototype blimp and the power required to propel it. (For water u 1.02x10 pa.s, p 1000 kg/m' and for air a 1.81x10 pa.s, p 1.2kg/m')arrow_forwardA tanker 300 m long is to be tested by a 1: 50 scale model. If the ship is to travel at 46 km/h, at what speed must the model be towed to obtain dynamic similarity (neglecting friction) with its prototype?arrow_forwardA model of an aircraft is being tested in a wind-tunnel. If the model was replaced by one that is half the size but is otherwise identical, what would be the ratio of the drag on the large model to the drag on the small model for exactly the same flow conditions. Give your answer to two decimal places. The model is in a region where drag coefficent is independent of Reynolds number.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