飞秒激光电子激发标记测速方法及其在超声速射流中的试验验证

Femtosecond laser electronic excitation tagging for velocity measurement in supersonic jet

  • 摘要: 为了研究飞秒激光电子激发标记测速方法在超声速流场中的适用性,利用该技术进行了超声速速度场的测量与二维轴向速度场重建的研究。将飞秒激光激发流场空气中的氮气分子作为示踪分子,示踪分子随流场移动并发出荧光,通过测量示踪分子所发出的荧光信号在固定时间内的位移来进行测速。运用该技术研究了轴对称的超声速自由射流的速度场分布情况,获得了超声速射流的轴向速度变化和不同高度速度的一维分布,在此基础上重建了超声速射流的二维轴向速度场,并给出了速度测量误差。

     

    Abstract: The velocity profile of supersonic jet measured by femtosecond laser electronic excitation tagging (FLEET) is discussed in order to study the applicability of the FLEET in the supersonic flow field. A femtosecond laser is used to excite nitrogen molecules as tracer molecules in the flow field. The tracer molecules move with the flow field and emit fluorescence, and the velocity is calculated by the ratio of the displacement of fluorescence emission to a certain time. The velocity field of an axisymmetric supersonic free jet is studied. The axial velocity and one-dimensional velocity distribution at different axial heights are obtained. On this basis, the two-dimensional axial velocity profile of the supersonic jet is reconstructed, and the velocity measurement error is given.

     

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