Honeycomb Structure - Aerodynamics

Aerodynamics

A honeycomb mesh is often used in aerodynamics to reduce or to create wind turbulence. It is also used to obtain a standard profile in a wind tunnel (temperature, flow speed). A major factor in choosing the right mesh is the length ratio (length vs honeycomb cell diameter) L/d.

Length ratio < 1: Honeycomb meshes of low length ratio can be used on vehicles front grille. Beside the esthetic reasons, these meshes are used as screens to get a uniform profile and to reduce the intensity of turbulence.

Length ratio >> 1: Basically, those honeycombs reduce lateral turbulence and eddies of the flow. Early wind tunnels used them with no screens. Unfortunately, this method introduced high turbulence intensity in the test section. Most modern tunnels use both honeycomb and screens.

While aluminium honeycombs are common use in the industry, other materials are offered for specific applications. People using metal structures should take care of removing burrs as they can introduce additional turbulences. Polycarbonate structures are a low-cost alternative.

The honeycombed, screened center of this open-circuit air intake for Langley's first wind tunnel ensured a steady, nonturbulent flow of air. Two mechanics pose near the entrance end of the actual tunnel, where air was pulled into the test section through a honeycomb arrangement to smooth the flow.

Honeycomb is not the only cross-section available in order to reduce eddies in an airflow. Square, rectangular, circular and hexagonal cross-sections are other choices available, although honeycomb is generally the preferred choice.