Q1: The drag on a 2m-diameter satellite dish due to an 80 km/hr wind is to be determinedthrough a water tunnel test using a geometrically similar 0.25m-diameter model dish.(a) At what water speed should the model test be run?(b) With all similarity conditions satisfied, the measured drag on the model was determined to be200 N. What is the predicted drag on the prototype dish?(c) What is the Mach number, Ma = u/a where a is the speed of sound, for the prototype air flowand the one in the water tunnel?PS: The kinematic viscosity of air is 1.56 x10-5 m²/s.-The kinematic viscosity of water is 1.0 x10-6 m²/s. The speed of sound is 340 m/s in air and 1500 m/s in water.

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Answered: Q1: The drag on a 2m-diameter satellite…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

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(b) A wind-tunnel experiment is performed on a small 1:5 linear-scale model of a car, in order to assess the drag force F on a new full-size car design. A dimensionless "drag coefficient" Ca is defined by C, =- pu'A where A is the maximum cross-sectional area of the car in the flow. With the model car, a force of 3 N was recorded at a flow velocity u of 6 m s. Assuming that flow conditions are comparable (i.e., at the same Reynolds number), calculate the expected drag force for the full-sized car when the flow velocity past it is 31 m s (equivalent to 70 miles per hour). [The density of air p= 1.2 kg m.]
(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 DAD
2) A prototype ship is 50 m long and designed for cruising speed of 10 m/s. The drag is to be simulatedby a 1-m-long model that will be towed in a towing tank. Using Froude scaling, determine the tow speedand the ratio of the model to prototype drag and power.
1. (a) The motion of a floating vessel through the surrounding fluid results in a drag force D which is thought to depend upon the vessel's speed v, its length I, the density p and dynamic viscosity μ of the fluid and the acceleration due to gravity g. Show that:- D = pv²1² (1) (b) In order to predict the drag on a full scale 50m long ship traveling at 7m/s in sea water at 5°C of density 1027.7225 kg/m³ and viscosity 1.62 x 103 Pa.s, a model 3m long is tested in a liquid of density 805 kg/m³. What speed does the model need to be tested at and what is the required viscosity of the liquid?
using pure water at 20°C. The velocity of the prototype in seawater (p = A 1/18 scale model of the submarine is to be tested in the water tunnel 1015 kg/m³, v = 1.4x106 m²/s) is 3 m/s. Determine: a) the speed of the water in the water tunnel for dynamic similarity D) the ratio of the drag force on the model to the drag force on the prototype
A prototype automobile is designed for cold weather inDenver, CO ( - 10 ° C, 83 kPa). Its drag force is tobe tested on a one-seventh-scale model in a wind tunnelat 150 mi/h, 20 ° C, and 1 atm. If the model and prototypeare to satisfy dynamic similarity, what prototypevelocity, in mi/h, needs to be matched? Comment onyour result.
2 A prototype car is designed for cold weather operation in Denver (-10°C, 83 kPa, altitude 1600m, µ = 1.741 × 10-5 Pas). It's drag force is to be tested in a 1:7 model in a wind tunnel at 150 mph under standard sea level conditions. If the model and prototype satisfy dynamic similarity what prototype velocity, in mph, is matched? Is this a reasonable test? 1 mile = 1609 m HINT: p = pRT
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')
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).
Question 3 The aerodynamic derivative X, may be determined from the following expression: X -pU SCD %3D where p is the air density, S is the wing area, U is the airspeed, and Cp is the drag coefficient. Consider an aircraft of weight 68 kN and wing area 43 m?, flying straight and level under international standard atmosphere (ISA) conditions, where p 1.018 kg/m, at an airspeed of 155 m/s. The aircraft %3D has a drag polar Cp = 0.011 + where Ci is the lift coefficient. Calculate the value of X, at this flight condition. Give your answer in units of Ns/m.
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An 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 is

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