Forced air at
Estimate the surface temperature of the chip if it is dissipating 30 mW.
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- Air at 1000C flows at an inlet velocity of 2 m/s between two parallel flat plates spaced 1 cm apart. Estimate the distance from the entrance to the point where the boundary layers meet.arrow_forwardOn March 16, 1990, an Air Force SR-71 set a new continental speedrecord, averaging a velocity of 2112 mi/h at an altitude of 80,000 ft.Calculate the temperature (in degrees Fahrenheit) at a stagnation point onthe vehicle.arrow_forwardAir enters a pipe of 1-cm diameter and 1.2-m length at p1 = 220 kPa and T1 = 300 K. If f = 0.025 and the exit pressure is p2 = 140 kPa, estimate the mass flow for (a) isothermal flow and (b) adiabatic flow.arrow_forward
- Imagine a plate 1 m long by 1 m wide at a temperature of 80 °C. Water is passed over its surface at a speed of 1 m/s with a temperature of 40 °C.Calculate the heat dissipated by the plate. Assume the following properties of water at 60 °C: k=0.651 W/mK, Pr=3.02, v =0.478 x 10-6 m²/s.arrow_forwardThe shock waves on a vehicle in supersonic flight cause a component ofdrag called supersonic wave drag Dw. Define the wave-drag coefficient asCD,w = Dw/q∞S, where S is a suitable reference area for the body. Insupersonic flight, the flow is governed in part by its thermodynamicproperties, given by the specific heats at constant pressure cp and atconstant volume cv. Define the ratio cp/cv ≡ γ . Using Buckingham’spi theorem, show that CD,w = f (M∞, γ ). Neglect the influence of friction.arrow_forwardConsider a Lear jet flying at a velocity of 250 m/s at an altitude of 10 km,where the density and temperature are 0.414 kg/m3 and 223 K,respectively. Consider also a one-fifth scale model of the Lear jet beingtested in a wind tunnel in the laboratory. The pressure in the test section ofthe wind tunnel is 1 atm = 1.01 × 105 N/m2. Calculate the necessaryvelocity, temperature, and density of the airflow in the wind-tunnel testsection such that the lift and drag coefficients are the same for thewind-tunnel model and the actual airplane in flight.arrow_forward
- An airfoil is in a freestream where p.(assigned altitude)atm, p(density) (assigned altitude) kg/m3, and V 980 m/s. At a point on the airfoil surface, the pressure is 0.5 atm. Assuming isentropic flow, calculate the velocity at that point. assigned altitude 36.22kmarrow_forwardOne type of supersonic wind tunnel is a blow-down tunnel, where air is stored in a high-pressure reservoir, and then, upon the opening of a valve, exhausted through the tunnel into a vacuum tank or simply into the open atmosphere at the downstream end of the tunnel. For this example, weconsider just the high-pressure reservoir as a storage tank that is being charged with air by a high-pressure pump. As air is being pumped into the constant-volume reservoir, the air pressure inside the reservoir increases. The pump continues to charge the reservoir until the desired pressure is achieved.Consider a reservoir with an internal volume of 30 m3. As air is pumped into the reservoir, the air pressure inside the reservoir continually increases with time. Consider the instant during the charging process when the reservoir pressure is 10 atm. Assume the air temperature inside the reservoir is held constant at 300 K by means of a heat exchanger.Air is pumped into the reservoir at the rate of 1…arrow_forwardAir at 20°C flows at V = 80.0 m/s over a smooth flat plate of length L = 17.5 m. Plot the turbulent boundary layer profile in physical variables (u as a function of y) at x = L. Compare the profile generated by the one-seventh-power law, the log law, and Spalding’s law of the wall, assuming that the boundary layer is fully turbulent from the beginning of the plate.arrow_forward
- Assume 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_forwardAir flows at Q=5 m³/s in a 1-m diameter stainless steel duct (roughness of 0.002 mm) the air properties are (-1.23 kg/m³ and -1.8 x 10^5N-s/m²). Approximate the minimum length of the duct so that entrance lengths can be ignored in the calculation of the pressure drop. a.41.1 m b.206 m c.20.6 m d.0411 Option a is incorrectarrow_forwardAn expression for the laminar velocity profile on a flat plate is u=C1sin(C2y)+C3 Where the argument of the sine function is in radians. Using the three common physicalconditions that the velocity profile should satisfy, determine d) the skin friction coefficient, Cf as a function of lengthe) displacement thickness (δ*/x) as a function of lengthf) the momentum thickness (θ/x) as a function of lengthg) the drag force (FD) on both sides of the platearrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning