Exam 2 - Normal and Oblique Shock Waves / Expansion Waves

The angle that dictates the minimum strength and maximum angle (beta) of the oblique shock wave that forms at the tip of the body

What is a vertex angle (theta)?

Angled (beta) flow discontinuity that forms when a supersonic flow encounters a sudden but shallow obstruction or corner. Leads to an immediate decrease in the flow’s speed and an increase in pressure, density, and temperature. Flow typically remains supersonic

What is an oblique shock wave?

An expansion wave is a continuous, isentropic (reversible) flow phenomenon that occurs when a supersonic fluid turns away from itself (e.g., around a convex corner or in a diverging duct), causing the flow to accelerate (Mach number increases) and its static pressure, temperature, and density to smoothly decrease.

What is an expansion wave?

a physical rotation of the airfoil sections about the spanwise axis.

What is geometric twist?

Changes the wing's camber or airfoil section shape along the span, which alters the local zero-lift angle (²$\alpha_{L=0}$) of the airfoil

What is aerodynamic twist?

Thin, non-isentropic flow discontinuity that occurs in a supersonic flow when the fluid is compressed so abruptly that pressure, density, temperature, and entropy increase suddenly, while velocity decreases

What is a shockwave?

A sound wave is an infinitesimal, isentropic (reversible) pressure disturbance that travels at the local speed of sound, whereas a shock wave is a strong, non-isentropic (irreversible) pressure discontinuity that travels faster than sound, causing abrupt jumps in fluid properties and entropy.

What is the difference between a sound wave and a shock wave?

It is the half-angle of the Mach cone that emanates from a moving point source in supersonic flow, calculated as mu = arcsin(1/M)

What is Mach angle (mu)?

It is the angle of the oblique shock wave formed at the tip of a wedge or corner.

What is wave angle (beta)?

It is the angle of the physical solid boundary (like a wedge surface) that causes the flow to turn.

What is deflection angle?

uses the smaller wave angle (beta) and results in a supersonic downstream flow

What is a weak solution for an oblique shock wave?

uses the larger wave angle, resulting in a subsonic downstream flow with greater total pressure loss

What is a strong solution for an oblique shock wave?

the largest possible angle (^theta) that a supersonic flow can be turned by a straight solid surface while maintaining an attached oblique shock wave.

What is the maximum deflection angle?

a straight, stable oblique shock wave that forms directly at the tip (vertex) of a sharp-nosed object, such as a sharp wedge or a cone, when it is placed in a supersonic flow.

What is an attached shock?

a curved, strong shock wave that stands ahead of the nose of the body and is not directly connected to the vertex

What is a detached shock?

a specific type of isentropic (reversible) flow phenomenon that occurs when a supersonic flow (M > 1) is forced to turn away from itself (e.g., around a convex corner or through a gradually diverging duct)

What are Prandtl-Meyer Expansion Waves?