Question 4 of 4 · Fluid Properties and Flow Regimes · Intermediate · About 17 min

Sound-speed check in a gas-flow tunnel

A diagnostic probe is exposed to a uniform air stream moving at $145\,\mathrm{m/s}$ in a controlled gas-flow tunnel. The absolute air temperature is $292\,\mathrm K$ . Model the gas as ideal with specific heat ratio $k=1.40$ and specific gas constant $R=287\,\mathrm{J/(kg\,K)}$ . Estimate the local speed of sound and the flow Mach number.

Air stream passing a probe in a straight test duct at known temperature. — Schematic, not to scale unless dimensions are given.

Given

Air-stream speed: 145 m/s
Absolute temperature: 292 K
Heat-capacity ratio: 1.40
Gas constant: 287 J/(kg·K)

Find

Speed of sound
Mach number

Assumptions

Ideal gas with constant heat-capacity ratio.
Temperature is absolute.

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Sound-speed check in a gas-flow tunnel

Given

Find

Assumptions

Worked solution