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为了改善对旋风机在非设计工况时的性能,提出了两级叶轮等功率、第二级叶轮变转速匹配运行方法,即在工况变化时,调整第二级叶轮的转速,使第二级叶轮功率始终与第一级叶轮功率相同.利用理论分析、数值模拟和实验研究的方法,分析了对旋风机在两级叶轮等转速运行和第二级叶轮变转速匹配运行时的特性.研究表明:等转速运行时,第二级叶轮压升与功率受流量变化影响剧烈,导致小流量工况时第二级电机过载烧毁及大流量工况时风机压升与效率迅速下降;第二级叶轮变转速匹配改善了第二级叶轮的功率、效率特性,使对旋风机的压升特性更加平稳,由此减小了小流量工况时第二级叶轮的负荷,增大了大流量工况时第二级叶轮的压升与效率,风机的高效工作范围由33.18％拓宽至37.88％,阻塞工况裕度由36.9％拓宽至48.2％.“,”Speed matching for the second impeller with equal power of two impellers is proposed to improve the performances of counter-rotating fan under off-design conditions,where the speed of second impeller is adjusted until the power of second impeller gets equal to one of first impeller.The fan performances during constant speed operating and during the second impeller speed matching operating are presented and discussed by theoretical analysis,numerical simulation and experimental research.It is revealed that the pressure-rise and power of the second impeller are changed significantly with varying mass flow during constant speed operating,leading to overload of the second motor under low flow rates and rapidly lowering pressure-rise and efficiency of the second impeller under high flow rates.The speed matching of the second impeller operating improves power and efficiency characteristics of the second impeller.Thus,pressure-rise and power characteristics of the fan become flatter.The load of the second impeller under low flow rates is lowered,and the pressure-rise and efficiency of the second impeller under high flow rates are heightened.The efficient working range of the fan is widened from 33.18％ to 37.88％,and the blocking condition margin is widened from 36.9％ to 48.2％.