A student needs to measure the drag on a prototype of characteristicdimension d p moving at velocity U p in air at standardatmospheric conditions. He constructs a model ofcharacteristic dimension d m , such that the ratio d p / d m issome factor f . He then measures the drag on the model atdynamically similar conditions (also with air at standardatmospheric conditions). The student claims that the dragforce on the prototype will be identical to that measured onthe model. Is this claim correct? Explain.

You are designing an airfoil for a new hobby RC plane.  Because of your limited knowledge, you have mistakenly approximated your airfoil as an ellipse with a = 75mm and b = 12mm.  Here, “a” is the depth of your wing and “b” is the thickness.  Your plane travels through the air at approximately 20mph (8.9m/s).  As it does so, skin friction produces a drag-induced heat of 800W on your wind, of length 1m. Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), TInfinity = 25oC a) What is the average temperature of your wing?  Assume an ellipse perimeter of approximately 200mm.

An ongoing research to investigate the unsteady aerodynamics of insect flight is being conducted at the Fluid Mechanics Laboratory in NUS; the outcomes of which are important in the development Flapping Micro-Air-Vehicles. As part of this research, an experiment has been conducted on a simplified two-dimensional elliptic wing to study the effect of sinusoidal heaving (i.e. moving up and down) and pitching (1.e. oscillating) motion of the wing on the generation of propulsion force. The wing has a chord length (distance between the leading and trailing edge of the wing) of c, and is pitching about the mid-chord (i.e. c/2 from the leading edge) as shown in Figure 3(a). The thrust or propulsive force of the wing (I) is expected to be a function of free stream velocity (U), chord length (c), frequency of heaving (f), amplitude of heaving (A), frequency of pitching (2), angular amplitude of pitching (a), density of fluid (p) and dynamic viscosity (u). Rewrite this relation in non-dimensional…

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.

The drag force (Fdrag) exerted by air on a moving car depends on a dimensionless drag coefficient (Carag), the specific volume of air (Vair), the velocity of the car (Var), and the frontal area of the car (Afront). (a) Based on unit considerations alone, obtain an equation for the drag force. Be sure to explicitly demonstrate that the final units are correct. (b) Explain, based on your equation, what happens to the drag force when each variable is changed in isolation. Indicate whether this predicted behaviour matches your intuition in each case.

This exercise is part of a series of problems aimed at modeling a situation by progressively refining our model to take into account more and more parameters. This progressive approach is very close to what professional scientists do! context We want to lower a suspended load in a controlled way so that it hits the ground with a speed whose modulus is not too great. To slow down the descent, a spring has been added behind the mass (A), The suspended load (B) is connected by a rope passing through a pulley to this mass (A), which slides on a horizontal surface with friction.   Information The masses of the charges A and B are known.The mass of the rope itself is negligible (very small compared to the loads).The pulley has negligible mass and can rotate without friction.The charge B is initially stationary and is at a known height h.The surface on which mass A sits is tilted upwards at a known angle theta from the horizontal.There is friction under mass A: the kinetic friction…

Step by step work starting with the formula.

When tested in water at 20 ° C fl owing at 2 m/s, an 8 - cmdiametersphere has a measured drag of 5 N. What will bethe velocity and drag force on a 1.5-m-diameter weatherballoon moored in sea-level standard air under dynamicallysimilar conditions?

A prototype ship is 50 m long and designed for cruising speed of 10 m/s. The drag is to be simulated by a 1-m-long model that will be towed in a towing tank. Using Froude scaling, determine the tow speed and the ratio of the model to prototype drag and power.

Some engineers want a good estimate of drag and boundary-layerthickness at the trailing edge of a miniature wing. The chord and span ofthe wing are 6 mm and 30 mm, respectively and a typical flight speed is5 m/s in air (kinematic viscosity = 15 × 10−6 m2/s; density = 1.2kg/m3). An engineer may decide to make a superseding model withchord and span of 150 mm and 750 mm, respectively. Measurements onthe model in a water channel flowing at 0.5 m/s (kinematic viscosity = 1× 10−6 m2/s, density = 1000 kg/m3) give a drag of 0.19 N and aboundary-layer thickness of 3 mm. Estimate the corresponding values forthe prototype