Influence of periodic temperature excitation on mixing performance and small signal gain coefficient of mixing gasdynamic CO2 laser
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摘要: 将基于周期性温度激励的主动控制技术引入混合型气动CO2激光器（MGDL）研究，通过数值计算深入研究了周期性温度激励对MGDL主/副气流混合特性及小信号增益系数的影响。研究结果表明：与未施加周期性温度激励的情形相比，在MGDL副喷管出口位置施加特定幅值及特定频率的周期性温度激励后，可以显著增强主/副气流的混合效果并大幅提高混合喷管中的小信号增益系数。激励幅值和激励频率对主/副气流混合特性及小信号增益系数有重要影响：随着激励幅值的增加，小信号增益系数先增大后减小；在混合喷管下游区域，文中所选的六种激励频率条件下获得的小信号增益系数均高于未施加周期性温度激励时的情形；随着激励频率的增加，主/副气流的混合效果越来越好，但当激励频率增加到一定值后，主/副气流的混合效果不再发生变化。
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关键词:
- 混合型气动CO2激光器 /
- 周期性温度激励 /
- 混合增强 /
- 小信号增益系数
Abstract: Initiative control technology based on periodic temperature excitation was used for mixing gasdynamic CO2 laser(MGDL). Through numerical simulation, influences of periodic temperature excitation on mixing characteristic of donor and assistant flows and small signal gain coefficient of mixing gasdynamic CO2 laser were studied. Investigation results indicate that compared with the case that has no periodic temperature excitation, mixing efficiency of donor and assistant flows can be enhanced and small signal gain coefficient in mixing nozzle can be improved when periodic temperature excitation with certain excitation amplitude and excitation frequency is imposed at the outlet of assistant nozzle. Excitation amplitude and excitation frequency have important effects on mixing efficiency of donor and assistant flows and small signal gain coefficient. As the excitation amplitude increases, the small signal gain coefficient first increases and then decreases. In downstream area of mixing nozzle, small signal gain coefficients under the condition of the six excitation frequencies selected by this paper are all higher than the state without periodic temperature excitation. With the increase of excitation frequency, mixing efficiency of donor and assistant flows becomes better and better; but when the excitation frequency increases up to a certain value, mixing efficiency of donor and assistant flows will not change any more. -
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