Development Of 3D Hydraulic Design Software For Centrifugal Pump Based On Open CASCADE

Centrifugal pump is widely used because of its wide range of application,uniform flow and small volume.In some special fields,the use amount accounts for more than 70% of the total pump.In order to improve the design accuracy and efficiency of centrifugal pump and keep up with the development trend of informatization and intelligence,it is imperative to develop a professional and high-precision centrifugal pump design software.Through the joint programming of C++,Open CASCADE and Qt,this paper studied the curve optimization and 3D automatic modeling by using NURBS curve and LSPIA optimization method,calculated the geometric parameters of centrifugal pump based on the velocity coefficient method,and finally integrated the curve optimization,3D modeling and centrifugal pump parameter calculation,and developed a systematic centrifugal pump design software LPCAD.The work and conclusions of this paper are summarized as follows:1.The research status of centrifugal pump CAD software and centrifugal pump design software at home and abroad is introduced in detail,and the differences between centrifugal pump CAD software at home and abroad are analyzed;The application of free curve in centrifugal pump design and the research status of NURBS curve fitting optimization method are introduced.2.The platform is built on Visual Studio 2015,focusing on the data transmission methods between different windows.When transmitting values between the main window and the sub window,the signal & slot mechanism of Qt is used to complete the value transmission between the windows by sending signals and triggering slot functions;The static variable mechanism in C++ is used between sub windows,and then the values are stored and read through the static member variables in the class,so as to achieve the data transfer function between sub windows.The realization of data transmission function between different windows provides support for subsequent centrifugal pump design function,modeling function and various human-computer interaction functions.3.The influence of control point,weight and node vector on NURBS curve is studied and analyzed.Combined with the function provided in Open CASCADE,based on the optimization of control point,the LSPIA method is realized by comprehensively using 3 optimization methods: control point optimization,parameter optimization and weight optimization.The combined 3 optimization methods are applied to the design of centrifugal pump.The effectiveness of LSPIA method is analyzed and verified.It is found that:(1)The LSPIA-optimized fitting curve can be widely used in all aspects of centrifugal pump design,including discrete point fitting,blade axial section drawing,streamline drawing in wooden pattern drawing,etc.LSPIA optimization can effectively reduce the curve fitting error and ensure the overall smoothness of the curve.(2)LSPIA optimization effects are different in different scenarios.LSPIA algorithm works best when fitting discrete data points,and the error decreases by more than 99.95% after 10 iterations.(3)After the shape of the curve is approximately stable,LSPIA optimization will reduce the fitting error by a certain percentage,and the fitting error of the curve can be reduced by 48.2% with each average iteration.(4)The unreasonable shape of the curve will affect the effect of LSPIA algorithm.The worst example has a 93.4%reduction in error after 10 iterations.4.The design and modeling algorithm of centrifugal pump impeller and volute are explored,and the three-dimensional hydraulic design software of impeller and volute is developed based on Open CASCADE and speed coefficient method.The research results are as follows:(1)The mathematical models and algorithms of each step in impeller design and volute design are mainly studied,including impeller shaft surface drawing design,F-L drawing,streamline separation point,grid deployment,blade thickening,three-dimensional blade modeling,volute section design,spiral section design,diffusion section design,tongue separation design,etc.On this basis,the software can be used to design the twisted impeller blade,the cylindrical blade,clockwise rotating blade,counter clockwise rotating blade,the middle outlet and the side outlet of the volute.(2)Aiming at the possible extreme situations in 3-D hydraulic design,personalized algorithms such as surface extension,streamline sweeping and adding transition section are researched and developed to improve the robustness of the design software.(3)Three centrifugal pumps with different specific speeds are designed by using the software,and CFD calculation and test verification are carried out.It is found that under the design working condition,the deviation between the design head and the test results of the three centrifugal pumps is within 5%,and the deviation between the efficiency and the test results is within 2%.It is proved that the software is suitable for the design of centrifugal pumps with different specific speeds and has a wide range of application.