| 摘要 |
FIELD: engines and pumps.SUBSTANCE: engine has front and rear air screws with variable-rake. In cruising flight, engine runs at constant air screw tip peripheral speed. In, at least, liftoff, climb or approach, blade tip peripheral speed exceeds that in cruising speed. Blades are closed from their rake in cruising flight to that in approach. Front air screw 23 has, at least, nine blades (Nf=9) and diameter Df. Rear air screw 24 has maximum number of blades Nr=Nf minus, at least, three. Front and rear air screws 23, 24 are separated by axial clearance x. Ratio x/Df varies from 0.15 to 0.4. Engine may be gas turbine, diesel or gasoline engine, or that running on fuel cells.EFFECT: reduced noise.11 cl, 5 dwg |
