A student engineer is given a summer job to find the drag force on a new unmaned aerial vehicle that travels at a cruising speed
of 320 km/h in air at 15 C. The student decided to build a 1/50 scale model and test it in a water tunnel at the same temperature.
(a) What conditions are required to ensure the similarity of scale model and prototype.
(b) Find the water speed required to model the prototype.
(c) If the drag force on the model is 5 kN, determine the drag force on the prototype
(a) What conditions are required to ensure the similarity of scale model and prototype.
(b) Find the water speed required to model the prototype.
(c) If the drag force on the model is 5 kN, determine the drag force on the prototype
1 answer:
Answer:
b. 1232.08 km/hr
c. 1.02 kn
Explanation:
a) For dynamic similar conditions, the non-dimensional terms R/ρ V2 L2 and ρVL/ μ should be same for both prototype and its model. For these non-dimensional terms , R is drag force, V is velocity in m/s, μ is dynamic viscosity, ρ is density and L is length parameter.
See attachment for the remaining.
You might be interested in
Answer:
Final length of the rod = 13.90 in
Explanation:
Cross Sectional Area of the polythene rod, A = 0.04 in²
Original length of the polythene rod, l = 10 inches
Tensile modulus for the polymer, E = 25,000 psi
Viscosity,
Weight = 358 lbs - f
time, t = 1 hr = 3600 sec
Stress is given by:
Based on Maxwell's equation, the strain is given by:
Strain = Extension/(original Length)
0.39022 = Extension/10
Extension = 0.39022 * 10
Extension = 3.9022 in
Extension = Final length - Original length
3.9022 = Final length - 10
Final length = 10 + 3.9022
Final length = 13.9022 in
Final length = 13.90 in