[shaoyikai813]

Hello everyone,
Any of you has done Tumble ratio report? I have got tumble ratio of 0.002 from what I have done. It is clearly wrong. Hope any of you can point out what I have done wrong? Thank you

As the picture shows below, I am going to have the tumble ratio at engine speed of 4500rpm along the axis which is pointed out with star in this picture.


I created a Cartesian coordinate shows below, therefore Z aixs will be the aixs crankshaft spins.


Settings:


I am not sure what mean by Tumble origin. In tutorial says center of cylinder. But my axis is not at center.

[pary07]

Hi shaoyikai813,

Just want to clarify and ask, were you able to calculate tumble using this method of the report?

[Mikemon]

Have you guys been able to use Tumble Ratio and to get reasonable values? I'm getting resoults like 0,00005

[ping]

from looking at that old first vector scene image the user has not created the local csys at the required tumble center location and at the correct orientation. i have used this report in the past with success but you need to follow the help directions carefully. and a very low result might mean your engine has very low tumble of course

[MRI]

In the steve-portal there is a best practice guide for steady state port flow. In a nutshell there are the following points to consider:

• create a local coord-sys for the cylinder
• create a single region for the cylinder part (the displacement chamber)
• Always use the swirl report in ice-cases. Switch the coordinate to consider swirl or tumble (z-axis for swirl, x- and y-axis for tumble)

With that you get swirl = sum{rho_i V_i [(X_i-X_m)v_i-(Y_i-Y_m)u_i]} / (2 pi n/60 sum{rho_i V_i [(X_i-X_m)^2+(Y_i-Y_m)^2]} ) I think that is the same like pary07 looked for in antother thread.

For what do you need the tumble values? For further 1D-Simulations?