Operational Mode and Optimization of Ducting Fans.

The paper first examines the theoretical basis underlying the reciprocal relationship between the wall forces originating from the fan blade and the pressure forces involved in fan air flow, and thus derives the basic Euler equation for turbo-machines. The various designs of ducting fans in current use in German coal mines are described. The ducting fan characteristic is then demonstrated based on such basic concepts as volume flow and pressure increase coupled with throughput and drive capacity; special emphasis is placed on parallel and series switched multiple ducting fan layouts. There follows a description of a test stand for fan characteristics designed according to present-day standards.