A numerical investigation of internal surface roughness and its influence on additively manufactured inlet manifold performance

What is it about?

Additive manufacturing techniques are being extensively used in an automotive industry where custom, high-performance manifolds are often required. One of the important factors in achieving high intake manifold performance is internal surface roughness. It is important to know the maximum permissible internal surface roughness value for a given complicated geometry of intake manifold in order to achieve an optimum performance. This study attempts to objectively assess the impact of different interior surface roughness on an intake manifold's performance using the simulation program Ansys Fluent. An arbitrary surface roughness value (Ra) is translated into an equivalent roughness of sand grain height for analysis and simulation. To address turbulence, a k-Ɛ turbulent model with a standard wall function is proposed. Outcome of the investigation indicates that air flow velocity close to the intake manifold’s outlet was affected by surface roughness. The maximum velocity at the intake manifold outlet of a 1.25 mm rough surface is found to be 18% lower than that of a smooth surface.

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