Turbulence results in the generation of noise and an increased static pressure drop in the system. Therefore, the airflow at the entrance and exit of a fan
should be as smooth as possible to minimise the generation of turbulence. For this reason, fitting (such as elbows and transitions) should not be placed
too close to a fan. This is illustrated in Figure 58 and Figure 59, which show examples of good and bad air flow conditions for fan installation