Study On The Influence Of Geometrical Parameters Of A Balanced Orifice Plate & Development Of Design Software

As a new type of non-standard orifice plate,the balanced orifice plate has the advantages of shorter straight pipe length requirement,small permanent pressure loss and wide measurement range compared with the standard orifice plate,and has a wide application prospect in flow measurement.However,the application of balanced orifice plate technique was limited due to lack of a complete mechanical parameter design theory and method.In this work,influences of the main mechanical factors on the performance of a balance orifice plate are investigated using numerical simulation and experiment methods.Based on the database of optimal balanced orifice plate parameters obtained in the work,a balance orifice plate design software was developed.The main contents and results are as follows:(1)Analysis of balanced orifice plate flow measurement principle and influence factors.Based on the Bernoulli’s equation and the continuity equation,the volume flowrate formula for a orifice plate is derived.Three orifice plate pressure taking types are introduced,i.e.diameter distance pressure taking,flange pressure taking and angle connection pressure taking,and it is determined that the flange pressure taking method will be used in this work.The discharge coefficient and pressure loss coefficient are the two main parameters for a balanced orifice plate,the standard deviation and linearity are chosen to evaluate the stability of the discharge coefficient.(2)Numerical simulation on the mechanical parameter influences to a balance orifice plate.The effects of the number of function holes,distribution position,orifice thickness,equivalent diameter ratio and pipe diameter on the discharge coefficient,pressure loss coefficient,momentum difference and other performance indexes of the balanced orifice plate are systematically studied.It is proposed to use the momentum difference as an auxiliary index to evaluate the performance of a balanced orifice plate.The method to determine the size of the function orifice of a balanced orifice plate was studied,then the optimized data of the optimal function orifice number and position,and orifice plate thickness,for a series balanced orifice plates DN50～DN1000 were obtained by numerical simulation.At the end,the relationship between some quantities and the equivalent diameter ratio were obtained,including optimal mechanical parameters,the pressure loss coefficient,and the ratio of pressure loss coefficient to differential pressure.(3)Software design and experimental validation.Based on the database of optimized mechanical parameters of balanced orifice plate obtained by the numerical simulation,the balanced orifice plate design software was developed using computer language C#.Several sets of balanced orifice plate were designed with the developed design software,and the designed orifice plates was tested experimentally.The results show that the accuracy of the designed balanced orifice plate reached 0.5%after flow calibration,and the deviation of the discharge coefficient between experimental calibration and software design is within 8.5%,which can meet the engineering design needs.