How do different fan mesh patterns affect fan and chassis airflow?

Is your chassis still equipped with this old style exhaust fan mesh? How about replacing a better one to improve performance?

The cooling performance of chassis is not
only determined by fan size, the number of fans, and the airflow
layout, but also by the type of exhaust fan grille/mesh that the fan is
attached to. It is impossible to reach the maximum air flow in a
computer system because the components inside the chassis cause
resistance, which prevents fans from achieving their maximum air flow
capability (please refer to the previous article: What is air
pressure?). To understand how we can achieve more efficient air flow by
using the right fan grille/mesh, we need to calculate the ratio of the
opening. The higher the exhaust ratio is, the lower the air resistance
and therefore, resulting in higher maximum air flow from the fans.

Why lower area ratio of exhaust air will result in higher air flow resistance and noise?

When the ratio of exhaust
air is lower, more air flow produced by the fan is pressing against the
grille/mesh, resulting is higher energy loss. Therefore, the higher the
ratio of exhaust air, the better air flow performance becomes.

The following table is a
comparison of different styles of fan grille/mesh. This data retrieved
from all grille/mesh are conducted under identical condition. The
results clearly show that wire grille has the best performance of all
fan grille/mesh solutions.

Why wire grille can result in lower noise?

Stamped out mesh pattern
found on many chassis, regardless of the venting holes shape, have
areas that sits vertical to the air flow path. This results in air
bouncing back from non-vented area of the mesh, creating small pockets
of air swirls and turbulence. Air turbulence such as these is a major
contributor to chassis noise. With wire grille, the air flows more
smoothly due to the rounded shape of the grille so the noise is
significantly lower.

The air flow line of mesh venting holes section

Since 2005, nearly all mainstream and premium SilverStone chassis models have implemented wire grilles as standard equipment.