A wind tunnel is used to measure the pressure distribution

Chapter 7, Problem 32P

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Problem 32P

A wind tunnel is used to measure the pressure distribution in the airflow over an airplane model (Fig. P7-34). The air speed in the wind tunnel is low enough that compressible effects are negligible. As discussed in Chap. 5, the Bernoulli equation approximation is valid in such a flow situation everywhere except very close to the body surface or wind tunnel wall surfaces and in the wake region behind the model. Far away from the model, the air flows at speed V͚ and pressure P͚ , and the air density ρ is approximately constant. Gravitational effects are generally negligible in airflows. so we write the Bernoulli equation as

Nondimensionalize the equation, and generate an expression for the pressure coefficient Cp, at any point in the flow where the Bernoulli equation is valid. Cp is defined as