The drag force of a new sports car is to be predicted at a speed of 65 mi/h at an air temperature of 25 C. Automotive engineers build a 0.333333333333333 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.

The drag force of a new sports car is to be predicted at a speed of 65 mi/h at an air temperature of 25 C. Automotive engineers build a 0.333333333333333 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.

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 5.8P

See similar textbooks

Similar questions

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 aerodynamic drag of a new sports car is to be predicted at a speed of 60.0 mi/h at an air temperature of 25°C. Automotive engineers build a one-third scale model of the car to test in a wind tunnel. The temperature of the wind tunnel air is also 25°C. The drag force is measured with a drag balance, and the moving belt is used to simulate the moving ground (from the car’s frame of reference). 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
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.
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.
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 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
A model pump has an impeller diameter of 30 cm. During a manufacturer's test, this model achieved an efficiency of 80%. A prototype in the same family (geometrically similar) is 10 times larger than this tested model. Under the same operating conditions dynamically similar to those in the model test, what most approximately will be the efficiency of the prototype pump? O 74% OOOO O 64% O 84% O 94%
Here, there is a human powered submarine. The length of the submarine is 4.85 m and the hope is it can travel fully submerged through water at 0.440 m/s. The water it is being tested in is freshwater at a Temperature of 15 degrees celcius. The submarine model is built on a 1/5 scale and is built in a wind tunnel. A shield surrounds the drag balance strut so that the aerodynamic drag of the strut itself does not influence the measured drag. Here, the wind in the wind tunnel is at 25°C and at one standard atm pressure. What air speed is needed to run the wind tunnel in order to achieve similarity?
The aerodynamic drag of a new sports car is to be predicted at a speed of 60 mph at an air temperature of 25°C. Automotive engineers build a one-third scale model of a car to test in a wind tunnel, shown in the figure below. The temperature of the wind tunnel air is also 25°C. The drag force is measured with a drag balance, and the moving belt is used to simulate the moving ground (from the car's frame of reference). The aerodynamic drag on the model in the wind tunnel is measured to be 34.5 lbf when the wind tunnel is operated at the speed that ensures similarity with the prototype car. Estimate the drag force (in lbf) on the prototype car at the given conditions. For air at T = 25°C and atmospheric pressure, p=1.184 kg/m3 and u-1.849-10-5 kg/m-s. Wind tunnel test section Pm Pm Fo.m Moving belt Drag balance The drag force on the prototype car is estimated to be Ibf.
A dimensional analysis is performed on the drag on a boat. When the effects of viscosity can be neglected, the Euler number based on the drag D experienced by the boat is a function of a Froude number. The effects of the dimensions of the boat can be represented by its length I. The drag on a model of the model is measured as 0.35N. If the ratio of / for a full-scale model to the value of/ for the model is 46, calculate the expected drag on the full-scale boat. Your answer should be to the nearest kN. The properties of the water in the model test matches those for the full-scale boat.
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?