Furthermore, the larger, and volume configurable duct volume behind the fan represents a volume into which the fixed intake aperture air volume is fed, thus representing a diffusion of the intake air mass, and a consequent pressure drop in {HEAD ~ the duct} behind {TAIL ~ the turbine type fan} 
behind
Furthermore , the larger , and volume configurable duct volume behind the fan represents a volume into which the fixed intake aperture air volume is fed , thus representing a diffusion of the intake air mass , and a consequent pressure drop in { HEAD ~ the duct } behind { TAIL ~ the turbine type fan }
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