Enunciado

Da Tabela 7.2, o coeficiente de arrasto de uma placa larga ao escoamento é aproximadamente 2,0. As condições do escoamento são U ∞ e p ∞ . Se a pressão média sobre a parte frontal da placa for aproximadamente igual à pressão de estagnação da corrente livre, qual será a pressão média na parte traseira?

Passo 1

E vamo lá!

Bora lá, se temos o coeficiente de atrito igual a 2,0, podemos fazer que:

F a r r a s t e = 2,0 ρ 2 U ∞ 2 A p l a c a ≈ p e s t a g n a ç ã o - p t r a s e i r a A p l a c a

Ou,

p t r a s e i r a ≈ p e s t a g n a ç ã o - ρ U ∞ 2

De Bernoulli, teremos

p e s t a g n a ç ã o = p ∞ + ρ 2 U ∞ 2

Assim, obteremos que:

p t r a s e i r a ≈ p ∞ - ρ 2 U ∞ 2

Resposta

p t r a s e i r a ≈ p ∞ - ρ 2 U ∞ 2

Ver Outros Exercícios desse livro

Exercícios de Livros Relacionados

The AMTRAK Acela train passes through Kingston, RI, at130 mi/h, scaring all the villagers daily. Its total weight is624 short tons, with a rolling resistance Crr
It is diffi cult to defi ne the “frontal area” of a motorcycledue to its complex shape. One then measures the drag area(that is, CDA) in area units. Hoerner [12] reports the dragarea of a typical moto
A delivery vehicle carries a long sign on top, as in Fig.P7.56. If the sign is very thin and the vehicle moves at65 mi/h, (a) estimate the force on the sign with no crosswindand (b) discuss the effect
The Army’s new ATPS personnel parachute is said to beable to bring a 400-lbf load, trooper plus pack, to ground at16 ft/s in “mile-high” Denver, Colorado. If we assume thatTable 7.3 is valid, what is
If a missile takes off vertically from sea level and leavesthe atmosphere, it has zero drag when it starts and zerodrag when it finishes. It follows that the drag must be amaximum somewhere in between