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How do shock waves increase drag?
When an aircraft approaches the speed of sound, the airflow over the wing reaches supersonic speed before the airplane itself does, and a shock wave forms on the wing. The airflow behind the shock wave breaks up into a turbulent wake, increasing drag.
Why can shock wave boundary layer interaction cause flow separation?
The supersonic boundary layer separation is a “free interaction” process between the boundary layer and the outer supersonic flow. The incident shock forms sharp adverse pressure gradients in the boundary layer, which causes the separation of the boundary layer.
What is a Mach stem?
If the explosion occurs above the ground, when the expanding blast wave strikes the surface of the earth, it is reflected off the ground to form a second shock wave traveling behind the first. The reflected blast wave merges with the incident shock wave to form a single wave, known as the Mach Stem. …
How are shockwaves related to the boundary layer?
If the air flowing over the blades in the engine was still supersonic, it would create shockwaves across the blades which would generate oscillations that would damage the system. The role of diffusers is to create oblique shockwaves that slow airflow to subsonic speeds before it enters the fan for the engine.
How are shock waves created in a diffuser?
They typically do this by inducing shock waves prior to the engine inlet. In this report several diffuser geometries were modeled to create oblique shock waves to reduce air speed with less stagnation pressure losses and drag than normal shock waves would create. These geometries include single ramp, double ramp, curved ramp, and a
Why are oblique shockwaves used in supersonic engines?
Oblique shockwaves are preferred because they create less pressure loss and drag throughout the system and make the engine more efficient. The two major geometries utilized in supersonic nozzle design are conic geometries and ramp geometries. Conic inlets are the most common design for air breathing engines and are