【作者】 王永安；

【导师】 田树军；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2009， 博士

【摘要】 液压集成块是集成式液压系统的核心零部件,其内部流动特性直接影响液压系统的能耗和工作性能。从工程实用的角度,液压集成块不仅应具有良好的结构形态,还要具有与其所属液压系统的既定设计要求相匹配的通流品质。本文结合国家自然科学基金项目,以在结构优化设计的基础上实现性能寻优为目标,系统地研究了集成块内流系统的微观流动特性和耗能机理,建立起提高液压集成块通流性能的性能设计准则,依次实现对集成块设计方案的性能评价和方案优选;同时定量校验所得集成块设计结果的性能品质,取得了预期的成果。通过对国内外同类研究现状和成果的总结,本文提出针对液压集成块结构优化设计所得结果群体实施性能优选和校验,从而实现对液压集成块性能优化的的设计策略。这是一种复杂的带多性能约束的工程设计问题。其中,性能约束来源于对液压管流特性的深入研究,隶属于流体力学的研究范畴。根据液压集成块性能评估系统的功能需求,采用功能驱动的系统规划原理,对液压集成块的设计方案考核、性能评价优选、性能校验以及三者的集成方式进行了详细规划,建立起液压集成块性能评估系统的结构体系和总体工作流程。在此基础上,针对液压集成块管网的结构特点及液压管流的理化特性,提出用于液压集成块管流特性研究的计算流体力学(CFD)关键性建模技术,并实验验证了方法的可行性及结果的可靠性。为全文的研究奠定了基础。针对液压管流雷诺数相对较低的特点,运用等效流场分布和分布参数方法建立了局部阻力系数的计算模型,由此得出局部液阻的低雷诺数局部阻力系数,实现了对局部液阻阻力特性的量化评价,而且对其规律进行了合理的阐述。该方法涵盖了局部液阻引起的全部损失,消除了管壁对流体固有摩擦的影响,提高了局部阻力系数结果的准确性和计算效率。在此基础上,深入研究典型局部液阻的液压管流特性及能耗机理,建立起以获得优良通流品质为目标的局部液阻结构设计规则。为了全面性、多角度地评价集成块复杂管网的通流品质,将无因次压降系数和耗散率分别作为评价复杂管网的阻力特性和能耗特性的性能指标。通过对典型复杂管网的CFD研究,揭示了其内部管流的复杂机理,分析了局部液阻之间的相互影响关系,阐述了管网组合方式、工艺孔属性和进出油孔道属性等对管网性能品质产生的影响,并量化评价了三类组合管网的性能品质。在此基础上,确定了面向集成块性能优化的管网结构设计规则。另外,建立了面向多工艺孔复杂管网的虚拟分块原则,为其流动特性的快速分析提供依据。为实现集成块结果群体中的方案寻优,提出基于多目标决策方法的集成块性能优选设计策略。将性能约束规则转化成性能子目标,采用线性加权和法建立起集成块性能品质的多目标决策模型;根据实施性能优化必备的原始设计信息,设计科学合理的信息数据结构,从性能优选设计的需求出发,科学地建立面向性能优选的开放式工程数据库系统;通过数据库技术自动识别结构设计结果的孔道结构特征,实现对集成块设计方案的性能考核;依据性能考核结果实施集成块性能品质的量化评价;根据结果样本的性能评价函数值,实现集成块设计方案的性能优选。为了快速、准确地校验液压集成块的管网性能,运用CFD和最小二乘支持向量机(LS-SVM)相结合的方法实现了管网压降的建模和预测。基于CFD的基础研究,确定出压降预测模型的参数驱动变量,并借鉴正交实验的方法提取模型的训练数据和测试数据,从而建立基于LS-SVM的压降预测模型。经对比研究确立适合用于管网压降参数化预测的核函数,并与基于BP神经网络的预测模型在预测精度、必要的训练样本数及训练时间等方面进行了对比。开发了面向工程应用的液压集成块管网压降校验的实用性工具软件系统。基于上述研究,应用VC++6.0开发环境和ObjectARX开发工具包,实现各个子模块的衔接及封装,开发出基于MDT环境的液压集成块性能评估系统,成功实现了液压集成块设计结果的性能优选设计。该软件系统主要包括数据输入模块、性能评价优选模块和管网性能校验模块三部分。通过典型工程实例验证了本系统的有效性及本文所用方法的可行性。更多还原

【Abstract】 Hydraulic Manifold Block(HMB) is the key part of the integrated hydraulic system, and energy loss and working performance of the hydraulic system are directly influenced by the flow performance. For engineering application, the design result of HMB need have good structure and the performance in according with the fixed design demand of hydraulic system. Combination with the National Natural Science Foundation project and taking permormance optimization baesd on structure optimization for object, the microcosmic flow and energy-loss mechanism is systematically investigated, and the design rules for enhancing through flow quality are established in the paper. Based above, the permormance appraisal and result optimization are achieved. And that the resistance characteristic of the design scheme is validated. The prospective achievements are obtained.After summarizing the research status at home and abroad, the optimization strategy is put forward to performance optimization by performance evaluation for structure design result population. It is a complex optimization design problem with muti-performance constraints which are derived from the thorough research on the hydraulic pipe flow, and belongs to the research category of hydrodynamics.According to the function requirements of performance evaluation system for HMB, a detailed planning is carried out based on functional driven system planning principle,including design scheme evaluation, performance appraisal and optimization, and performance validation. The architecture and work flow of the system are established.Based above, the key Computational Fluid Dynamics (CFD) technology for investigating on pipe flow mechanism inside HMB is presented, in accordance with the structure characteristic of the pipe inside HMB and the physicochemical properties of hydraulic pipe flow. The method possibility and the results reliability are validated by experiments.The work lays a foundation for the the paper.According to the characteristic of low Reynolds number inside hydraulic pipe flow, the computation modle of the local resistance number is established by the equivalent flow field and the distributed method, and the local resistance number at low Reynolds number are obtained. The resistance characteristic of local block is furthmore quantified, and the rules are reasonably explained. All local loss is included in the mothod, and the influence of wall on fluid is eliminated. The computation efficiency and the accuracy of local resistance coefficient are enhanced. Based above, the hydraulic pipe-flow characteristic and energy-comsuption mechanism are analyzed, and the structure design rules for local block inside HMB are determined to improve the throughflow performance.To comprehensivly evaluate the throughflow performance of the complex pipe inside HMB, the dimensionless pressuredrop coefficient and dissipation rate are used for evaluation index of resistance characteristic and energy-comsuption characteristic.by the CFD research on the typical complex channel, the complicated mechanism is revealed, and the nonlinear influence is analyzed. The influence of combination mode, attribute of aid hole and the input and output hole are described, and the throughflow quality of three combination channels are quantitatively evaluated. The structure design rules are determined for performance optimization of HMB. In addition, the virtual block rules are established for complex channel with fabrication holes, and its provide reference for engineering personnal to quickly analyze the complex flow characteristic.To realize the optimization for HMB results population, the optimization stratety based on Multi-Object Decision-Making method is presented. The perforamance constraints rules are converted to performance subgoals, and the Multi-Object Decision-Making model for HMB performance quality is established by linear weighted method.According to the original design data for performance optimization, the data structure is scientifically designed. From the requirement of performance optimization design, the engineering database system is built up. The automatic recognition of channel feature is achieved by database technology to appraisal the performance of the design scheme. The performance quality is quantitatively evaluated by the judgement result. The good scheme is determined by comparison with evaluation function value of the result sample.To calibrate the performance quality of HMB fastly and accurately, CFD in combination with Least Square Support Vector Machine (LS-SVM) is used to build the parametric model for pressuredrop prediction of channel. Based on the basic research by CFD, the parametric driving variables are determined, the training date and test date of the model are obtained by Orthogonal Experiments, and the pressuredrop prediction model is established with the kernel of LS-SVM model. By contrast, the kernel function suitable for pressuredrop prediction of channel is determined. The model is also compared with the prediction model based on BPNN in prediction accuracy, the number of necessary training samples and the training time. Practical tool software is successfully developed for engineering application to predict the pressurdrop of channel inside HMB.Based above research, VC++6.0 developing environment and ObjectARX developing toolkit are used to realize the connection and package of every submodules, the performance evaluation system is developed based on MDT software, and the performance optimization of the HMB design results are successfully achieved. Data input module, performance evaluation and selection module, and performance verification module of pipeline are incuded in the system. The effectiveness of the system and the feasibility of the method applied in the paper are validated by typical engineering example.更多还原