Vorticity of Aircraft Trailing Vortices

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In summary, the conversation discusses the topic of aircraft trailing vortices and the vorticity associated with them. The speaker has been studying the subject and has come across various papers discussing vortices, but is confused about the vorticity. They reference a book by Anderson which states that vortex flow is irrotational except at r = 0, but the vortices they have seen in papers have a non-zero vorticity. The conversation then delves into the concept of streamlines and their relation to vorticity, with the conclusion that vorticity is simply a measure of rotation in a flow.
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Danis
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I've recently been studying aircraft trailing vortices and have been reading various papers regarding vortices. However, my aerodynamics is very rusty, I've been confused about the vorticity of these vortices.

In Fundamentals of Aerodynamics (Anderson), Ch 3, Vortex flow is shown to be irrotational everywhere except when r = 0, which has infinitie voriticity. However, all the vortices that I've come across in various papers have a particular (non-zero) vorticity, eg a Gaussian profile for the Lamb-Oseen vortex.

Could someone please help me with this.

Cheers.
 
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What I think you're referring to are solutions to stream functions and things of that nature. By definition, vorticity is simply:
[tex]
\omega = \vec{\nabla} \times \vec{V}
[/tex]
When we think of flows, we can think of them of a summation of translational and vortical components. Vortices will certainly have both components as they can be thought of as spinning eddys, which translate with the mean flow.
 
  • #3
Danis said:
I've recently been studying aircraft trailing vortices and have been reading various papers regarding vortices. However, my aerodynamics is very rusty, I've been confused about the vorticity of these vortices.

In Fundamentals of Aerodynamics (Anderson), Ch 3, Vortex flow is shown to be irrotational everywhere except when r = 0, which has infinitie voriticity. However, all the vortices that I've come across in various papers have a particular (non-zero) vorticity, eg a Gaussian profile for the Lamb-Oseen vortex.

Could someone please help me with this.

Cheers.

What Anderson is referring to is that the streamlines in a vortex flow are irrotational. In other words if we imagine a parcel of fluid flowing around the streamline of a vortex flow the parcel does not itself rotate as it travels around the "circular" path. The streamline itself is a circular path, but the fluid in the streamline is not spinning. An example would be as if the Earth orbited the sun without the Earth spinning about it's own axis.

Saying that the streamline is irrotational means we are assuming inviscid (non-viscous) flows which simplifies things a whole bunch.

Hope that helps!
 

1. What is vorticity of aircraft trailing vortices?

Vorticity of aircraft trailing vortices refers to the rotating motion or spin of the air behind an aircraft as it moves through the atmosphere. This spinning motion creates a wake of vortices, or swirling air, which can potentially affect other aircraft flying behind it.

2. How are aircraft trailing vortices formed?

Aircraft trailing vortices are formed due to the difference in pressure above and below the wings of an aircraft. As air flows over the curved surface of the wings, it creates a low pressure area above and a high pressure area below. This pressure difference causes the air to rotate, forming the vortices.

3. What are the potential hazards of aircraft trailing vortices?

The primary hazard of aircraft trailing vortices is the potential for a smaller aircraft to encounter the wake turbulence created by a larger aircraft. This can cause loss of control, especially during takeoff and landing, and can be dangerous for aircraft flying in close proximity to each other.

4. How can the vorticity of aircraft trailing vortices be reduced?

There are several methods used to reduce the vorticity of aircraft trailing vortices, including wingtip devices such as winglets, vortex generators, and flared wingtips. These devices help to disrupt the formation of vortices and reduce their strength.

5. How is the vorticity of aircraft trailing vortices measured?

The vorticity of aircraft trailing vortices can be measured using a variety of techniques, including wind tunnel testing, computer simulations, and flight tests. These methods allow researchers to study the behavior and strength of vortices in different flight conditions and improve our understanding of their effects on aircraft.

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