A small wind tunnel in a university's undergraduate fluid flow laboratory has a test section that is 20 by 20 in in cross section and is 4.0 ft long. Its maximum speed is 145 ft s. Some students wish to build a model 18-wheeler to study how aerodynamic drag is affected by rounding off the back of the trailer. A full-size (prototype) tractor-trailer fig is 52 ft long. 8.33 ft wide, and 12 ft high. Both the air in the wind tunnel and the air flowing over the prototype are at
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Fluid Mechanics Fundamentals And Applications
- 1:25 scale model of a submarine is tested at 180 ft/s in a wind tunnel using sea-level standard air. What is the prototype speed in seawater at 20°C for dynamic similarity? If the model drag is 1.6lb, what is the prototype drag?arrow_forwardProblem 4: The power P developed by a wind turbine is a function of diameter D, air density p, wind speed V, and rotational rate @. Viscous effect is negligible. (4a) Rewrite the above relationship in a dimensionless form; (4b) In a wind tunnel, a small model with a diameter of 90cm, rotating at 1200 RPM (revolution per minute), delivered 200 watts when the wind speed is 12m/s. The data are to be used for a prototype of diameter of 50m and wind speed of 8 m/s. For dynamic similarity, what will be (i) the rotational speed of the prototype turbine? (ii) the power delivered by the prototype turbine? Assume air has sea-level density.arrow_forward3. In the study of aerodynamic drag on a stationary body, an appropriate non-dimensional grouping has been found to be: QAU3 where, P is the power lost, p is the density of the fluid, A is a typical area, and U is the velocity of the fluid. In laboratory tests with a 1:10 scale model (ratio of the length) at 25°C, the power lost was measured as 5 w when the air velocity was 0.5 m/s. Calculate the power lost in the prototype (kW) at 25°C when the air velocity is 1 m/s.arrow_forward
- A student team is to design a human-powered submarine for a design competition. The overall length of the prototype submarine is 95 (m), and its student designers hope that it can travel fully submerged through water at 0.440 m/s. The water is freshwater (a lake) at T = 15°C. The design team builds a one-fifth scale model to test in their university’s wind tunnel. A shield surrounds the drag balance strut so that the aerodynamic drag of the strut itself does not influence the measured drag. The air in the wind tunnel is at 25°C and at one standard atmosphere pressure. At what air speed do they need to run the wind tunnel in order to achievesimilarity?arrow_forwardAn underwater device which is 2m long is to be moved at 4 m/sec. If a geometrically similar model 40 cm long is tested in a variable pressure wind tunnel at a speed of 60 m/sec with the following information, Poir at Standard atmospheric pressure = 1.18kg/m³ Pwater = 998kg/m3 Hair = 1.80 x 10-5 Pa-s at local atmospheric pressure and Hwater = 1 × 10-3 Pa-s then the pressure of the air in the model used times local atmospheric pressure isarrow_forwardA paramecium is an elongated unicellular organism with approximately 50 μmin diameters and 150 μmin lengths. It swims through water by whip-like movements of cilia, small hairs on the outside of its body. Because it moves "head first" through the water, drag is determined primarily by its diameter and only secondarily by its length, so it's reasonable to model the paramecium as a 70-μm diameter sphere. A paramecium uses 2.0 PW of locomotive power to propel itself through 20∘C water, where 1 pW = 1 picowatt = 10−12W. What is its swimming speed in μm/s? Express your answer in micrometers per second.arrow_forward
- > | E9 docs.google.com/form تبديل الحساب Questions 7 نقاط Q1/ The power of 6-blade flat blade turbine agitator in a tank is a function of diameter of impeller, number of rotations of the impeller per unit time, viscosity and density of liquid. From a dimensional analysis, obtain a relation between the power and the four variables. 3. صفحة 2 منarrow_forwardDimensional analysis can be used in problems other than áuid mechanics ones. The important variablesaffecting the period of a vibrating beam (usually designated as T and with dimensions of time) are the beamlength `, area moment of inertia I, modulus of elasticity E, material density , and Poissonís ratio , so thatT = f cn(`; I; E; ; )Recall that the modulus of elasticity has typical units of N/m2 and Poissonís ratio is dimensionless.(a) Find dimensionless version of the functional relationship.(b) If E and I must always appear together (meaning that EI is e§ectively a single variable), Önd a dimensionless version of the functional relationship.arrow_forward8.1. An airplane wing of 3 m chord length moves through still air at 15°C and 101.3 kPa at a speed of 320 km/h. A !:20 scale model of this wing is placed in a wind tunnel, and dynamic similarity between model and prototype is desired. (a) What velocity is necessary in a tunnel where the air has the same pressure and temperature as that in flight? (b) What velocity is necessary in a variable-density wind tunnel where absolute pressure is 1 400 kPa and temperature is 15°C? (c) At what speed must the model move through water (15°C) for dynamic similarity?arrow_forward
- P1.20 A baseball, with m = 145 g, is thrown directly upward from the initial position z = 0 and Vo = 45 m/s. The air drag on the ball is CV², as in Prob. 1.19, where C~ 0.0013 N: s*/m". Set up a differential equation for the ball motion, and solve for the instantaneous velocity V(t) and position z(1). Find the maximum height zmax reached by the ball, and compare your results with the classical case of zero air drag.arrow_forwardKindly solve with full solution and explain. Thank you very mucharrow_forward(c) If a drag force of 214 N is measured o wind tunnel, a 1:20 scale model is created and tested at the same air temperature in order to determine the drag. A blimp typically flies at 20 m/s in air at standard conditions. In order to model the blimp's behavior in a LOAD (a) What is the AMO At a model velocity of 75 m/s, what is the appropriate air pressure in the wind tunnel? DO dimensionless parameter to use so that dynamic similarity is maintained? DO prototype be? CHE CHEGO EXAM yOT UPL OT on the model, what would the corresponding drag on the UPZ EXAM EXAM NOT U 20 NOT TO CHEC DADarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning