Nonlinear Modified Method on K-factor of Vortex Flowmeter Based on CPLD

There is a good repeatability of output frequency signals of vortex flowmeter in a wide flowrate range.However,the K-factor remains a constant in a narrow scope,which restraints the measurement range of vortex flowmeter.A nonlinear modified method of K-factor based on CPLD was given.The spline interpolation method was adopted to approximate relation curve of flowrate and K-factor.The modified algorithm was realized by optimization on look-up-table which was embedded in CPLD.Through experiments,it is indicated that the measurement range is expanded within accuracy level by vortex flowmeter with nonlinear modified method.Furthermore,this method is applicable in any other flowmeters which have the same nonlinear problem of K-factor.