Question

What is the characteristic of a normal shock flow?

1) Stagnation speed of sound
2) Stagnation temperature
3) Stagnation pressure
4) Stagnation density

Answer 1

A characteristic of normal shock flow in fluid dynamics is a significant drop in stagnation pressure, with other properties like temperature and density also undergoing changes.

Step-by-step explanation:

The characteristic of a normal shock flow in fluid dynamics is that there are abrupt changes in various properties of the flow. Among the options provided: stagnation speed of sound, stagnation temperature, stagnation pressure, and stagnation density, the stagnation pressure is a key characteristic that sees a significant drop across a normal shock. The other properties such as temperature and density will also change, with the temperature increasing and density rising as the fluid slows down across the shock. These changes occur because the normal shock represents a very rapid compression process wherein the fluid transitions from a supersonic to a subsonic state, leading to these alterations in the flow properties.

Answer 2

The characteristic of a normal shock flow is a decrease in stagnation pressure. Thus option (3) Stagnation pressure is correct answer.

Step-by-step explanation:

In a normal shock flow, as a fluid transitions from supersonic to subsonic speed, there's a sudden increase in pressure across the shock wave. The stagnation pressure, represented as p₀, decreases across the shock. This pressure decrease is governed by the relation across a normal shock, given by the equation p₂ / p₁ = 1 + ((γ - 1) / 2) * (M₁² - 1), where p₂ is the pressure after the shock, p₁ is the pressure before the shock, γ is the specific heat ratio, and M₁ is the Mach number before the shock. The decrease in stagnation pressure indicates a loss in total pressure due to the conversion of kinetic energy into pressure energy during the shock process.

Stagnation temperature and speed of sound remain unchanged across a normal shock. Stagnation temperature, denoted as T₀, remains constant in an adiabatic and isentropic process across the shock. The stagnation density, ρ₀, might change due to pressure and temperature variations, but it's not a defining characteristic of a normal shock. The key characteristic is the abrupt change in stagnation pressure while the stagnation temperature and speed of sound remain constant. This pressure change plays a vital role in understanding and analyzing compressible flow through various engineering applications.