An air tank of volume 1.5 m3 is initially at 800 kPa and20 °C. At t = 0, it begins exhausting through a convergingnozzle to sea-level conditions. The throat area is 0.75 cm2.Estimate (a) the initial mass flow in kg/s, (b) the timerequired to blow down to 500 kPa, and (c) the time atwhich the nozzle ceases being choked.

Methane (CH4) fl ows through an insulated 15-cm-diameterpipe with f -0.023. Entrance conditions are 600 kPa,1008C, and a mass fl ow of 5 kg/s. What lengths of pipe will(a) choke the fl ow, (b) raise the velocity by 50 percent, or(c) decrease the pressure by 50 percent?

Air, with stagnation conditions of 800 kPa and 100°C, ex pands isentropically to a section of a duct where A_{1} = 20 cm² and p_{1} = 47kPa . Compute (a) Ma₁, (b) the throat area, and (c) m. At section 2 between the throat and section 1, the area is 9 cm². (d) Estimate the Mach number at section 2.

The converging–diverging nozzle shown in Fig. P3.22expands and accelerates dry air to supersonic speeds at theexit, where p 2 = 8 kPa and T 2 = 240 K. At the throat, p 1=284 kPa, T 1 = 665 K, and V 1 = 517 m/s. For steadycompressible fl ow of an ideal gas, estimate ( a ) the mass fl owin kg/h, ( b ) the velocity V 2 , and ( c ) the Mach number Ma 2 .