Apparatus for maintaining constant mass flow

An apparatus intended for placing in the path of a fluid flow, e.g. an airstream to maintain a substantially constant mass flow in the flow path downstream of the apparatus independent of pressure alterations in the flow path upstream of the apparatus, said apparatus comprising a regulator housing (1) with a fluid inlet (2) to which the flow path upstream of the apparatus is connected, a fluid outlet (3) to which the flow path downstream of the apparatus is connected and a plurality of throughput passages in the housing, extending from the inlet to the outlet, in said passage, there being arranged a plurality of movable damper elements (7) operable from outside the housing, the adjustment of which causes alteration of the throughput cross-sectional area of the passages, each damper element comprising a damper blade (7), angular in cross section, and having a substantially planar forward blade portion (9) and a substantially planar rear blade portion (10) connected thereto which forms an obtuse angle with the forward blade portion, each said damper blade being carried by and attached to a damper shaft (11) pivotally mounted in the housing and extending transversely through the passage, whereby the throughput cross-sectional area is determined primarily by the size of a gap (35) between each rear blade portion (10) and a first, fixed wall portion in an adjacent passage, and secondarily by an intermediate space (36) between each forward blade portion (9) and a second fixed or movable wall portion in an adjacent passage and that the damper blade position in the passages is determined by the torque equilibrium about the damper shafts resulting from the fluid forces generated by the fluid mass flow on the forward and rear blade portions, and a torque with which the damper shafts are affected by an adjustable mass body system (14) carried by and acting on a counterweight neck (13) interconnected with the damper shafts and projecting outwardly from the outside of the housing, a baffle plate (15) mounted transverse to the passage and attached to the housing for each damper blade (7), the baffle plate extending between the parallel side walls (4) of the passage, and extending with a planar, forward plate portion (17) in the flow direction from the region of the damper blade shaft (11) down to a line parallel with this shaft beneath and downstream of the shaft, from which line the plate continues outwards with a planar rear plate portion (18) parallel to the top (5) and bottom (6) walls of the passage towards the fluid outlet (3).