If the air is not drawn into the fan inlet evenly <a title="Cheap Zach Collins Jersey" http://www.cheapnbablazersjerseys.com/zach-collins-jersey/ , performance deficiencies will result from the combined effects of turbulence and uneven air distribution. When the system attempts to change the direction of flow, the air hugs the outside of the inlet elbow entering the fan. This causes uneven, turbulent airflow into the fan. Fans perform correctly when air flows straight into the inlet. Air should be drawn into the fan inlet with an evenly distributed velocity profile.