5- The wind force on a particular type of building depends on the wind speed, the size of the building, and the density and viscosity of the air. (a) Express the relationship between these variables in terms of dimensionless groups. (b) A scale model is to be used to assess the forces on the building caused by 30-meter-per-hour winds on the full- scale building. If a one-half scale model of the building is tested in a wind tunnel, what airspeed must be used in the model? Using the required airspeed, the measured force on a particular component of the model is 100 N, what is the magnitude of the corresponding force in the

5- The wind force on a particular type of building depends on the wind speed, the size of the building, and the density and viscosity of the air. (a) Express the relationship between these variables in terms of dimensionless groups. (b) A scale model is to be used to assess the forces on the building caused by 30-meter-per-hour winds on the full- scale building. If a one-half scale model of the building is tested in a wind tunnel, what airspeed must be used in the model? Using the required airspeed, the measured force on a particular component of the model is 100 N, what is the magnitude of the corresponding force in the

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 5.18P: The drag on an airplane wing in flight is known to be a function of the density of air (), the...

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5.13 The torque due to the frictional resistance of the oil film between a rotating shaft and its bearing is found to be dependent on the force F normal to the shaft, the speed of rotation N of the shaft, the dynamic viscosity of the oil, and the shaft diameter D. Establish a correlation among these variables by using dimensional analysis.
The drag on an airplane wing in flight is known to be a function of the density of air (), the viscosity of air(), the free-stream velocity (U), a characteristic dimension of the wing (s), and the shear stress on the surface of the wing (s). Show that the dimensionless drag, sU2, can be expressed as a function of the Reynolds number, Us.
A fighter aircraft is to operate at 200 m/s in air at standard conditions (p= 1.2 kg/m³). A model is constructed to 1/20 scale (length ratio) and tested in a wind tunnel at the same air temperature (same air viscosity) to determine the drag force. The drag force Fp is a function of the air density p and viscosity µ, the velocity V and the cross section length of the airplane D. a) Use dimensional analysis to prove that: F, and PV²D² pVD What are these two dimensionless numbers? b) If the model is tested at 50 m/s, what air density should be used in the wind tunnel? Comment the result and give a recommendation. c) If the model drag force is 250 N at 50 m/s, what will be the drag force of the prototype? Lift force 200 m/s Drag force
The drag force on a truck moving at a speed of 95 km/h is to be estimated using the measured data of a similar 1:10 scale model tested in a wind tunnel, Standard air is the fluid in both the prototype and the model, The truck frontal area is 10.7 m and the measured drag force on the model is 3000 N. Determine: a) the air velocity used in the wind tunnel model tests, and b) the prototype drag force in terms of the measured model drag force.
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Question 5 a) A 1:20 scale model of a surface vessel is used to test the influence of a proposed design on the wave drag. A wave drag of 6.2 lb is measured at a model speed of 8.0 ft/sec. What speed does this correspond to on the prototype, and what wave drag is predicted for the prototype? Neglect viscous effects, and assume the same fluid for model and prototype. b) Discuss the modelling and types of similarities
Wind tunnel test section km/h Model FD Moving belt Drag balance The aerodynamic drag of a new Volvo FH truck is to be predicted at a speed of 85 km/h at an air temperature of 25°C (p=1.184 kg/m³, u=1.849x10-5kg/m-s). Volvo engineers build a 1/2 scale model of the FH to test in a wind tunnel. The temperature of the wind tunnel is also 25°C. The drag force is measured with a drag balance, and the moving belt is used to simulate the moving ground. Determine how fast the engineers should run the wind tunnel to achieve similarity between the model and the prototype.
A one-fourth scale model of a car is to be tested in a wind tunnel. The conditions of the actual car are V = 45 km/h and T = 0°C and the air temperature in the wind tunnel is 20°C. In order to achieve similarity between the model and the prototype, the wind tunnel is run at 180 km/h. The properties of air at 1 atm and 0°C: ? = 1.292 kg/m3, ? = 1.338 × 10−5 m2/s. The properties of air at 1 atm and 20°C: ? = 1.204 kg/m3, ? = 1.516 × 10−5 m2/s. If the average drag force on the model is measured to be 70 N, the drag force on the prototype is (a) 66.5 N (b) 70 N (c) 75.1 N (d ) 80.6 N (e) 90 N
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The drag force of a new sports car is to be predicted at a speed of 70 mi/h at an air temperature of 25 C. Automotive engineers build a 0.2 scale model of the car to test in a wind tunnel. The temperature of the wind tunnel air is also 25 C. Determine how fast (in mi/h) the engineers should run the wind tunnel to achieve similarity between the model and the prototype.
Water X 50-mm inside diameter The volume flow rate of the system The pressure at the point "A" The pressure at the point "B" 25-mm diameter As a consultant at one of the country's leading soft drink companies, you are tasked with evaluating the system depicted to determine the following parameters using Bernoulli's Equation if the values assigned to "X" and "Y" are 3m and 0.5m respectively: i. ii. iii.