a. The flow velocity in the test section of a low-speed subsonic wind tunnel is 100 mph. The test section is vented to the atmosphere, where atmospheric pressure is 1.01 × 105 N/m2. The air density in the flow is the standard sea-level value of 1.23 kg/m3. The contraction ratio of the nozzle is 10-to-1. Calculate the reservoir pressure in atmospheres.
b. By how much must the reservoir pressure be increased to achieve 200 mph in the test section of this wind tunnel? Comment on the magnitude of this increase in pressure relative to the increase in test-section velocity.