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-   -   Perforated sheet with hexagonal holes!? (http://www.cfd-online.com/Forums/cfx/115973-perforated-sheet-hexagonal-holes.html)

oj.bulmer April 10, 2013 09:34

Perforated sheet with hexagonal holes!?
 
Hi

I want some good literature on performance of perforated sheet with hexagonal holes. While Idelchik's "Handbook of Hydraulic Resistance" has abundant information about circular hole patterns, it has no mention of hexagonal holes.

Entire day of searching and I could stumble upon just two references. One is a published paper claiming hexagonal holes produce smaller pressure drop than circular ones, and other is a patent (yea, I have to search patents now, in the absence of literature :rolleyes:) which claims the velocity distribution for hex holes is smooth etc.

I want some good literature beforehand that gives resistance coefficients \left( \zeta =\frac {\Delta P} {\frac{1}{2} \rho v^2} \right) for different percentages of open areas and thickness to hole diameter ratio etc, or at least something. I can always do a unitary cell symmetric arrangement of hexagonal hole to understand the characteristics, but it is time consuming and it is not possible to cover all types of perf sheets in limited time.

Thanks
OJ

evcelica April 11, 2013 23:11

These types of parametric analyses are what workbench is good at. You can do you unitary cell symmetric arrangement, but define your geometry parametrically, and make an expression for the pressure drop that is an output parameter. Then set up your ranges of input parameters and hit update all results.


I hate searching all day and coming up with nothing! at least if the computers running you are making some progress and feel better.

oj.bulmer April 12, 2013 23:03

Thanks but such a comprehensive study is my last resort. I always insist on some literature search before I launch a serious investigation. I have already done a study of symmetrical unitary cell for circular holes and the results seem to be sensitive to meshes. I had to use close to 5 million cells to achieve a mesh independence solution. But then, I did this study just to compare the results versus Idelchik's data, to understand if my approach is reasonable, and my results were within 1% of that of Idelchik's predictions.

Since different open areas and t/d ratios will alter the geometry signifiacantly, the mesh independence for a range of these cases would be necessary, and the computational effort thus is mammoth.

It always is beneficial to have a bit of patience while combing through literature. I have (pleasantly) surprised myself for enough no. of times to believe that :)

OJ


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