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Non-axisymmetric wake impact experiments were carried out after the best exciting frequency for a low speed axial compressor had been found by axisymmetric wake impact experiments. When the number and circumferential distribution of inlet guide vanes (IGV) are logical, the wakes of non-axisymmetric IGVs can exert beneficial unsteady exciting effect on their downstream rotor flow fields and improve the compressor's performance. In the present paper, four non-axisymmetric wake impact plans were found working better than the axisymmetric wake impact plan. Compared with the base plan, the best non-axisymmetric plan increased the compressor's peak efficiency, and the total pressure rise by 1.1 and 2%, and enhanced the stall margin by 4.4%. The main reason why non-axisymmetric plans worked better than the axisymmetric plan was explained as the change of the unsteady exciting signal arising from IGV wakes. Besides the high-frequency components, the nonaxisymmetric plan generated a beneficial low-frequency square-wave exciting signal and other secondary frequency components. Compared with the axisymmetric plan, multifrequency exciting wakes arising from the non-axisymmetric plans are easier to get coupling relation with complex vortices such as clearance vortices, passage vortices and shedding vortices. 相似文献
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Rapid internal conversion in a symmetric molecule LD 700 studied by means of femtosecond fluorescence depletion 下载免费PDF全文
The rapid internal conversion dynamics at room temperature is
determined by using the femtosecond time-resolved fluorescence
depletion measurements of a complex solvated molecule of LD 700
(rhodamine 700) combined with steady-state absorption and
fluorescence spectroscopy, as well as quantum chemical calculation.
The molecule is excited by a 50fs laser pulse at 400nm which
directly populated the highly excited singlet state, the rapid
internal conversions (ICs) are observed, which leads to the
directional changes of the emission transition moment following
photoexcitation to the highly excited singlet state S5 of LD
700. 相似文献