The following formulas are commonly used by engineers to predict the lift and drag of an airfoil: where L and Dare the lift and drag forces, V is the airspeed, S is the wing span, is the air density, and CL and CD are the lift and drag coefficients. Both CL

The following formulas are commonly used by engineers to predict the lift and drag of an airfoil: where L and Dare the lift and drag forces, V is the airspeed, S is the wing span, is the air density, and CL and CD are the lift and drag coefficients. Both CL

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

(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.]
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
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.
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.
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
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?
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.
(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
A sphere is moving in water with a velocity of 1.6 m/s. Another sphere of twice the diameter is placed in a wind tunnel and tested with air which is 750 times less dense and 60 times less viscous (dynamically) than water. The velocity of air that will model dynamically similar conditions is
2. A student team is to design a human-powered submarine for a design competition. The overall length of the prototype submarine is 4.85 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, as shown in the Fig. 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 achieve similarity? Take for water at T = 15 °C and atmospheric pressure, p = 999.1 kg/m³ and µ = 1.138 × 10-³ Pa.s. Take for air at T = 25 °C and atmospheric pressure, p = 1.184 kg/m³ and µ = 1.849 × 10-³ Pa.s. V Por P Wind tunnel test section Model Shield FD Drag balance Strut
(Review experimental scaling) A lightweight parachute is being designed for military use. Its diameter D is 20 ft and the total weight W of the falling payload, parachute, and equipment is 190 lb. The design terminal settling speed V. (or terminal velocity) of the parachute at this weight is 16 ft/s. A one-twelfth scale model of the parachute is tested in a wind tunnel. The wind tunnel temperature and pressure are the same as those of the prototype, which is 70 °F and standard atmospheric pressure. a) Calculate the drag coefficient of the prototype. (Hint: At terminal velocity, speed is constant so weight is in equilibrium with aerodynamic drag.) b) At what speed should the wind tunnel be run in order to achieve dynamic similarity? c) Find the aerodynamic drag force of the model parachute in the wind tunnel in pounds. Payload
Given the following measurements of velocity for a falling object with m = 3kg: v, meters/seconds t, seconds 0 -1.424 -2.778 -4.068 -5.274 -6.426 -7.519 0 0.05 0.10 0.15 0.20 0.25 0.30 Use 4th Order Runge-Kutta to approximate the coefficient of drag, k, given the model: mv' = -mg - kv Approximate the terminal velocity and the time to reach terminal velocity of the falling object. Use g = 9.81m/s².