| 摘要 |
A vehicle turbine of the gas-coupled type propels the vehicle through a change-speed transmission. To reduce vehicle acceleration time with an acceptable penalty with respect to fuel consumption, the compressor of the engine has variable inlet guide vanes which are shifted into a positive prewhirl angle at idling speeds when the transmission is shifted into a drive condition. Thus the engine gas generator has a low speed idle, with axially oriented guide vanes and normal air entrance, when the transmission is in neutral, and a high speed idle with positive prewhirl when the transmission is in drive condition. Also, the vanes are shifted at full speed of the gas generator to provide negative prewhirl and thus reduce the engine speed corresponding to maximum power output. Because of the higher idle and lower maximum speeds, the acceleration time of the gas generator, and thus of the power turbine, is reduced. Because positive prewhirl reduces compressor pressure ratio at the high speed idle, the power turbine does not have an undue tendency to cause creep of the vehicle in the high speed idle.
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