Table of Contents
What happens in a convergent nozzle?
A convergent nozzle is a nozzle that starts big and gets smaller-a decrease in cross-sectional area. As a fluid enters the smaller cross-section, it has to speed up due to the conservation of mass. To maintain a constant amount of fluid moving through the restricted portion of the nozzle, the fluid must move faster.
What does boundary layer depend on?
Boundary layers may be either laminar (layered), or turbulent (disordered) depending on the value of the Reynolds number. For lower Reynolds numbers, the boundary layer is laminar and the streamwise velocity changes uniformly as one moves away from the wall, as shown on the left side of the figure.
Why does a boundary layer become turbulent?
Boundary layer flow over a wing surface begins as a smooth laminar flow. As the flow continues back from the leading edge, the laminar boundary layer increases in thickness. At some distance back from the leading edge, the smooth laminar flow breaks down and transitions to a turbulent flow.
What is boundary layer condition?
boundary layer, in fluid mechanics, thin layer of a flowing gas or liquid in contact with a surface such as that of an airplane wing or of the inside of a pipe. The flow in such boundary layers is generally laminar at the leading or upstream portion and turbulent in the trailing or downstream portion.
What is converging diverging?
Divergence generally means two things are moving apart while convergence implies that two forces are moving together. Divergence indicates that two trends move further away from each other while convergence indicates how they move closer together.
Why we use converging diverging nozzle?
In convergent-divergent type of nozzles we can increase the flow velocity much higher than sonic velocity that is why these type of nozzles have a wide applications such as propelling nozzles in jet engines or in air intake for engines working at high rpms.
What happens when a liquid enters a converging chamber?
When a liquid which is not swirling approaches an orifice through a converging chamber, it converges from all points of a cross-section, only decreasing in velocity in the boundary layer near the wall.
How does the boundary layer affect the shape of an object?
The external flow reacts to the edge of the boundary layer just as it would to the physical surface of an object. So the boundary layer gives any object an “effective” shape which is usually slightly different from the physical shape.
What are the effects of boundary layer on lift and drag?
The effects of the boundary layer on lift are contained in the lift coefficient and the effects on drag are contained in the drag coefficient. HISTORICAL NOTE: The theory which describes boundary layer effects was first presented by Ludwig Prandtl in the early 1900’s.
When was the boundary layer theory developed?
HISTORICAL NOTE: The theory which describes boundary layer effects was first presented by Ludwig Prandtl in the early 1900’s. The general fluids equations had been known for many years, but solutions to the equations did not properly describe observed flow effects (like wing stalls).