Calculate mean path length of a magnetic circuit

[TheRedDevil18]

Given this magnetic circuit:

With these dimensions:

With this equivalent circuit:

If I am using F = HL to calculate the mmf drops in RcoreAB(see equivalent circuit) and RcoreBCDA(see equivalent circuit) then how would I calculate L in the formula ?

 

[Hesch]

You have two loops ( left/right ). For the left loop you will have the drawn path length:

L_iron + L_air
L_air = 2s.

In air the permeability is μ₀, and in iron the permeability is μ = μ₀*μ_r.

The mean length is the length of the drawn path. So you could ask: What is the mean permeability in the loop ?

 

[Hesch]

#2: Figure comes here:

 

[TheRedDevil18]

So can I just sum the path directly in the middle of the loop or lamination ?, I heard that the center of the core is where the flux travels the most

 

[Hesch]

So can I just sum the path directly in the middle of the loop or lamination ?

Yes, as the dashed lines in the figure indicates.

I think the flux will be spread almost equally in the cross section area of the core.

It cannot be calculated precisely anyway, because the practical μ_r for iron depends on the direction wherein the iron plates have been rolled: A flux direction parallel to the roll-direction results in the greatest μ_r. But then there is a problem with the corners of the core, where the flux must change direction, crossing the roll-direction.

PS: You mean the center leg? Yes of course: double up. But normally the center leg has the double cross section area as well ( compared to the left/right leg ).