关键词: 涡轮机;风扇;压气机;涡轮

Abstract: Review on counter-rotating turbomachinery(CRT) is first presented.Then,two technique challenges on aspects of flow preswirl and off-design operation are analyzed by using velocity triangle method.It is shown that the range of preswirl angle will be more narrow and the off-design operation will be more complex in CRT except for more severe noise,vibration and perhaps high cycle fatigue problems.Some suggestions have been obtained.First,the precondition of adopting counter-rotation scheme is that the narrowed range of preswirl would still satisfy the engine cycle requirements.Secondly,CRT is more suitable for ones with low speed ratio and low flow coefficients.As to CRT with high speed ratio and high flow coefficients,the exit flow angle of preceding rotor should satisfy β1<40°～50°.Otherwise,the downstream rotor will have to change its stagger angle for counter-rotating fan or compressor.In some circumstances,the rotor also needs to change its stagger angle to resolve problems encountered in off-design operation with different speed.The present results can be directly used to judge the applicability of CRT and determine basic rules and ranges in selecting design parameters of CRT.

Key words: Turbine engine;Fan;Compressor;Turbine