How does the normal shock affect the different properties of a fluid?
The correct answer and explanation is:
A normal shock is a type of shock wave that occurs when the flow direction of a compressible fluid is perpendicular to the shock front. It typically happens when the flow velocity exceeds the speed of sound, and a sudden decrease in velocity occurs across the shock.
The key properties of a fluid affected by a normal shock include pressure, temperature, density, and velocity.
- Pressure: The pressure across a normal shock increases significantly. The shock compresses the fluid, resulting in a higher pressure downstream compared to upstream. This is one of the most significant changes observed in the flow due to the shock.
- Temperature: Temperature also increases across a normal shock. The kinetic energy of the fluid particles is converted into internal energy, leading to a rise in temperature downstream of the shock.
- Density: The density of the fluid increases after the shock. This is a direct result of the compression of the fluid due to the sudden deceleration caused by the shock wave. The increase in pressure contributes to the increased density.
- Velocity: The velocity of the fluid decreases dramatically as it passes through the shock. The fluid slows down from supersonic speeds to subsonic speeds after the shock. This reduction in velocity is essential for maintaining the stability of the shock wave.
In summary, a normal shock causes an abrupt transition in the flow properties of a compressible fluid. It leads to an increase in pressure, temperature, and density, while velocity decreases significantly. These changes are crucial for understanding the behavior of fluids in supersonic flow regimes, such as in nozzles and diffusers in aerodynamics and fluid dynamics applications.