The Numerical Method Of Finite Element Analysis For High Pressure Cavity 3D Flow Fields And Its Application Research For Optimize Design In The Spherical Regulated Pressure Units

This study employed a wide combination of various established techniques,including analytic fluid dynamics, computational fluid mechanics, numericalcomputing methods of flow field, scientific computation and visualization,experimental visualization in fluid flow, and computer digital image processing.Utilizing these tools, I derived the mathematical models that govern flow incomplicated conduits, including the two-equation model of turbulence and theinfinitesimal calculus equations of three-dimensional boundary layers. The finiteelement numerical calculation method was applied to simulate the velocity flow fieldand static/dynamic pressure field within high pressure cavity complex. The 3-Dnumerical simulation results were visualized based on computational visualizationtools. Based on these simulations, the detailed relationship between the fluid vibrationnoise, energy loss and the flow field structure were further analyzed qualitatively andquantitatively. In order to validate the numerical analysis, we tried to optimize thedesign of the spherical regulated pressure units, based on the finite element numericalcalculation and genetic algorithm. Finally, the optimized design was confirmedthrough experimental measures on the pressure loss and pressure pulsation. This workis of great significance for the future design of high-efficiency, low-energy-loss andlow-noise spherical regulated pressure units. The main research contents are asfollows:1. The hydraulic power system and its developing trends were reviewed, and theresearch purpose and significance of the thesis are related. I summarized variousnumerical methods of computational fluid mechanics and current applications ofcomputational fluid dynamics in hydraulic technique. Following that, I outlinedcurrent computational visualization technique of flow field, and surveyed variousflow field experimental visualization methods. The application of computer digitalimage processing technique in experimental visualization of flow field is furtherdiscussed.2. According to the principle of finite element, I derived the integral formula ofelliptic equation based upon continuity equation and Navier-Stokes equation. TheRanold shear stress shift equation, the turbulence one-equation model, and theturbulence two-equation model were further developed. Next, I discussed the physicalsignificances of each items and determined the value of the parameters. Thefundamental differential equation and the momentum integral equation forthree-dimensional thin boundary layer are obtained based on the derivationsmentioned above.3. The steps of fluid finite element numerical calculation were related in detail. Iapplied the fluid finite element method to simulate the three-dimensional flow field.The results were applied to the finite element analysis towards three-dimensionalflow field of the spherical regulated pressure units. Through the analysis, velocityvector distribution and static/dynamic pressure distribution for flow field wereobtained based on various model parameters. The influence of vortex on fluid noiseand energy loss were analyzed quantitatively.4. Based on the genetic optimization theory, I developed a method aiming atobtaining optimized structure parameters for spherical regulated pressure units.Lowering the pressure loss and reducing the pressure pulsation were set as theoptimization objectives. And under the constraint of a series of functions, the opticalgeometric and flow parameters are solved to minimize the pressure loss and pulsationof the spherical regulated pressure units. The pressure loss and pressure pulsationwere measured and the error was analyzed.