Consider the flow field over a circular cylinder mounted perpendicular to the flow in the test section of a low-speed subsonic wind tunnel. At standard sea level conditions, if the flow velocity at some region of the flow field exceeds about 250 mi/h, compressibility begins to have an effect in that region. Calculate the velocity of the flow in the test section of the wind tunnel above which compressibility effects begin to become important, i.e., above which we cannot accurately assume totally incompressible flow over the cylinder for the wind tunnel tests.
Want to see the full answer?
Check out a sample textbook solutionChapter 3 Solutions
Fundamentals of Aerodynamics
Additional Engineering Textbook Solutions
Vector Mechanics for Engineers: Statics and Dynamics
Engineering Mechanics: Statics & Dynamics (14th Edition)
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
INTERNATIONAL EDITION---Engineering Mechanics: Statics, 14th edition (SI unit)
Vector Mechanics for Engineers: Dynamics
Vector Mechanics for Engineers: Statics and Dynamics
- Consider a cone at zero angle of attack in a hypersonic flow. (Hypersonic flow is very high-speed flow, generally defined as any flow above a Mach number of 5.) The half-angle of the cone is θc, as shown inthe figure. An approximate expression for the pressure coefficient on the surface of ahypersonic body is given by the newtonian sine-squared law : Cp = 2 sin2 θcNote that Cp, hence, p, is constant along the inclined surface of the cone. Along the base of the body, we assume that p = p∞. Neglecting the effect of friction, obtain an expression for the drag coefficient of the cone, where CD is based on the area of the base Sb.arrow_forwardAssume an inviscid, incompressible flow. Also, standard sea level density and pressure are 1.23 kg/m3 (0.002377 slug/ft3) and 1.01 × 105 N/m2(2116 lb/ft2), respectively. Prove that the flow field specified is not incompressible;i.e., it is a compressible flow as stated without proof .arrow_forwardAn explosion occurs which creates a plane normal shock wave propagating into a region of air that is at rest (stagnation pressure po=1.0135×105Pa) and (stagnation temperature of To=290K). The speed of the shock is 1700 m/s. The air is modelled as an inviscid fluid, specific heat ratio γ=1.4 and gas constant R=287~J/kg⋅K. Calculate the air speed in m/s, relative to a stationary observer in the region behind the shock?arrow_forward
- Consider a wing mounted in the test-section of a subsonic wind tunnel. The velocity of the airflow is 160 ft/s. If the velocity at a point on the wing is 195 ft/s, what is the pressure coefficient at this point?arrow_forwardAn engineer is designing a subsonic wind tunnel. The test section is to have a cross-sectional area of 4 m2 and an airspeed of 60 m/s. The air density is 1.2 kg/m3. The area of the tunnel exit is 10 m2. The head loss through the tunnel is given by hL=0.025VT2/2g, where VT is the airspeed in the test section. Calculate the power needed to operate the wind tunnel. Hint: Assume negligible energy loss for the flow approaching the tunnel in region A, and assume atmospheric pressure at the outlet section of the tunnel. Assume α = 1.0 at all locations.arrow_forwardAssume an inviscid, incompressible flow. Also, standard sea level density and pressure are 1.23 kg/m3 (0.002377 slug/ft3) and 1.01 × 105 N/m2(2116 lb/ft2), respectively. Consider the flow field over a circular cylinder mounted perpendicular tothe flow in the test section of a low-speed subsonic wind tunnel. Atstandard sea level conditions, if the flow velocity at some region of theflow field exceeds about 250 mi/h, compressibility begins to have an effectin that region. Calculate the velocity of the flow in the test section of thewind tunnel above which compressibility effects begin to become important, i.e., above which we cannot accurately assume totallyincompressible flow over the cylinder for the wind tunnel tests.arrow_forward
- The actual car will be running at V= 35 km/h at p-1 atm and T=0°C (the air density and viscosity are 1.292 kg/m3, and 1.338 x 105 m2/s, respectively). A one-fifth scale car model is being tested at the wind tunnel at 198.3 km/h at 1 atm and 20°C. (The air density and viscosity are 1.204 kg/m³, and 1.516 x 10$ m²/s, respectively). The average drag force on the model is 50 N. What is the drag force on the prototype? Note that dimensionless drag is Cp 1/2pV² A O 41.8 N O 50 N O 15.0 N O 44.2 N O 8.4 N O 38.9 Narrow_forwardConsider a typical air flow around a cruising jetliner at 10km altitude. The speed is now 810 km/h, while the ambient conditions are 0.414 kg/m³ , 0.261 atm and -50°C. At the stagnation point, the temperature rises over by 25°C, while the density and pressure changes by more than 30% and 45 % respectively. Classify the following situations as compressible/incompressible flowarrow_forwardConsider a low-speed open-circuit subsonic wind tunnel. The tunnel is turned on, and the pressure difference between the inlet (the settling chamber) and the test section is read as a height difference of 10 cm on a U-tube mercury manometer. (The density of liquid mercury is 1.36 × 104 kg/m3.) Assume that a Pitot tube is inserted into the test-section flow of the wind tunnel. The tunnel test section is completely sealed from the outside ambient pressure. Calculate the total pressure measured by the Pitot tube, assuming the static pressure at the tunnel inlet is atmospheric. Given that A2/A1 = 1/12. (Round the final answer to two decimal places.) The total pressure measured by the Pitot tube is × 105 N/m2.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning