液压滑阀V型节流槽气穴流仿真分析及结构优化研究

利用Fluent软件的mixture混合模型及RNGκ-ε湍流模型对液压滑阀V型节流槽气穴流动进行模拟分析。通过动网格分析发现V型节流槽在小开度及大开度情况下气穴发生的位置及大小均不同。通过模拟分析发现,结构参数中节流槽楔形角W、节流槽夹角D对节流槽气穴流动的影响明显。根据V型节流槽气穴模拟分析结果,以参数W、D为自变量,以V型节流槽气体体积分数最大值为目标值,以Gauss函数为相关函数,采用常数回归模型,分别得到在小开度及大开度情况下的Kriging代理模型。利用改进遗传算法对Kriging近似代理模型进行优化计算,得到的优化V型节流槽结构抑制气穴性能明显。

气穴瞬变流基本方程特征根问题研究

建立了气穴瞬变流基本方程，并重点讨论了下述三种情况的基本方程的特征根问题：ａ．ｐ－ｐｉ≠０且计入附加质量力；ｂ．ｐ－ｐｉ＝０且计入附加质量力；ｃ．ｐ－ｐｉ＝０且不计入附加质量力．

Numerical simulation of bubble chaotic motion in a cavitating water jet

A computational fluid dynamics (CFD) method is developed to investigate the radical motion of single cavitating bubble in the oscillating pressure field of a cavitating water jet. Regarding water as a compressible fluid, the simulation is performed at different oscillating frequencies. It is found that the bubble motion presents obvious nonlinear feature, and bifurcation and chaos appear on some conditions. The results manifest the indetermination of the cavitating bubble motion in the oscillating pressure field of the cavitating water jet.

Computational Cavitation Flows at Inception and Light Stages on an Axial-Flow Pump Blade and in a Cage-Guided Control Valve

Cavitation flows induced around an axial-flow pump blade and inside a high pressure cage-type valve are simulated by a two-dimensional unsteady Navier-Stokes analysis with the simplest treatment of bubble dynamics. The fluid is assumed as a continuum of homogeneous dispersed mixture of water and vapor nuclei. The analysis is aimed to capture transient stages with high amplitude pressure change during the birth and collapse of the bubble especially at the stage of cavitation inception. By the pump blade analysis, in which the field pressure is moderate, cavitation number of the inception and locations of developed cavitation are found to agree with experimental results in a wide flow range between high incidence and negative incidence. In the valve flow analysis, in which the water pressure of 5MPa is reduced to 2MPa, pressure change responding to the bubble collapse between the vapor pressure lower than 1 KPa and the extreme pressure of higher than 104 KPa is captured through a stable computation. Location of the inception bubble and pressure force to the valve plug is found agree well with the respective experimental features.

Clinical study of optimizing acupoint combining in treatment of bronchial asthma with acupoint application

Objective:To observe the therapeutic efficacy of acupoint application at different groups of acupoints in treating bronchial asthma in remission stage.Methods:A total of 120 patients with bronchial asthma in remission stage were recruited and divided by the random number table method into acupoint application group 1,acupoint application group 2 and acupoint application group 3,with 40 cases in each group.In all the three groups,Tiantu(CV 22),Dazhui(GV 14)and Feishu(BL 13)were selected,with Dingchuan(EX-B 1)added in acupoint application group 1,Shenshu(BL 23)added in acupoint application group 2,and Gaohuang(BL 43)added in acupoint application group 3.Before intervention,one month and 3 months after intervention,clinical symptoms,peak expiratory flow(PEF)and forced expiratory volume in 1 second percentage of predicted value(FEV1%)of the three groups were observed,and their clinical efficacies were evaluated.Results:Comparing the therapeutic efficacy regarding traditional Chinese medicine symptoms and signs,after 1-month treatment,the total effective rate was 87.5%in acupoint application group 1,versus 62.5%in acupoint application group 2 and 55.0%in acupoint application group 3,and the between-group differences were statistically significant.After 3-month treatment,the total effective rate was 95.0%in acupoint application group 1,versus 70.0%in acupoint application group 2 and 65.0%in acupoint application group 3,and the between-group differences were statistically significant.After intervention,the three groups all showed significant improvements in pulmonary function with statistical significance;among the three groups,the improvement in acupoint application group 1 was more significant than that in the other two groups.Conclusion:Tiantu(CV 22),Dazhui(GV 14)and Feishu(BL 13)as basic prescription plus Dingchuan(EX-B 1)can improve symptoms of bronchial asthma in remission stage,and it works better in improving pulmonary function than the basic prescription plus Shenshu(BL 23)or Gaohuang(BL 43).

Influence of acupuncture on pulmonary function of patients with asthma： a review

Asthma is a common disease with recurrent onset which severely affects patients＇ quality of life. Acupuncture can improve pulmonary functions in asthma patients and thus treat this disorder. To summarize the status of acupuncture treatment for asthma, we have collected clinical literatures published in the recent 20 years and analyzed the influence of acupuncture on pulmonary functions in asthma patients from the aspects of frequently used points, needling techniques, manipulation and mechanisms to provide references for treating asthma with acupuncture.