| 摘要 |
<p>A contra-rotating pump or compressor unit is made axially compact by moving the fluid along concentric annular flow path portions between which the flow direction is reversed. The unit can comprise concentric contra-rotating sleeves (31, 32, 35) provided with impeller vanes or blades and defining the flow path portions between them, or axially adjacent contra-rotating impeller assemblies each comprising concentric rings with impeller vanes between them. The flow direction reversal can be effected either by fixed housing portions co-operating with the sleeves or rings or by annular walls (34, 62) connecting alternate sleeves (31, 32, 35) or rings.</p> |
