square fluctuation
1.The research result demonstrates that along with the increment of Reynolds number, the root mean square value of outer fluctuating magnitude of the external diameter in fall frequency band increases, the root mean square value of fluctuating magnitude of the external diameter in high frequency band decreses, demonstrating that the fluctuation of flexible pipe wall changes fluctuation don field of original rigid pipe, large-size eddy motion increases and small-size eddy motion decreases, this reduces energy loss and increases friction reduction effectiveness.
2.This paper analyzes the previous research on voltage fluctuation and flickermeter, and discusses the method of flicker measurement recommended by International Electrotechnical Commission standard IEC-61000-4-15. Based on IEC standards, the methods of designing square demodulator, bandpass-weighted filter, and smoothing filter are presented.
