共查询到19条相似文献，搜索用时 187 毫秒
1.
推导了两光滑平板间干气密封微尺度流动场的非线性雷诺方程,应用PH线性化方法、迭代法对非线性雷诺方程近似求解,得到气膜压力的近似解析式;利用极坐标下的流线方程,通过Maple程序求解压力方程和流线方程得到流线,此流线就是符合条件的拟合曲线。对拟合曲线槽干气密封气膜刚度进行计算与测试,并与螺旋槽进行比较。研究结果表明：在相同工况下,拟合曲线槽干气密封气膜刚度比螺旋槽大,且气膜刚度比螺旋槽稳定,这在工程实践中具有重要意义和应用价值。 相似文献
2.
气膜浮动密封已广泛应用于透平压缩机械中,但对于其轴套的槽型参数缺少系统的研究。针对气膜浮动密封运行原理与螺旋微槽的结构特点,在气膜润滑理论的基础上,建立了相应的数学模型。采用中心差分法对压力控制方程和气膜厚度方程进行了耦合求解,并验证了编制程序的正确性。计算获得了气膜浮动密封气膜的稳态特性参数,并分析讨论了工况参数改变时槽型结构参数对浮动密封稳态性能的影响。研究表明：当气膜浮动密封在所讨论的工况参数范围内,槽型参数在下列范围取值时能获得较优的综合密封性能：螺旋角α=28.5°,槽长L=12mm,槽数N=18。此研究结果为气膜浮动密封槽型的设计提供了理论依据。 相似文献
3.
以螺旋槽干气密封的动静环和密封气膜组成的系统为研究对象,在Solidworks中建立密封环三维耦合模型,Fluent中计算获得流场动压微气膜分布,将得到的微气膜数据载入Workbench平台的结构场和温度场,设置相应的刚性约束和边界条件,基于热-流-固耦合变形理论来分析密封环在热-流-固耦合下的应力、变形情况,研究不同压差下应力、变形的遵循规律。结果表明：动静环的应力在密封环外径处较大,热-流-固耦合下变形最大区域在中径处。随着压差的增大,密封环的应力、变形均增大,在一定压差范围内动环的应力大于静环,而静环的变形大于动环。 相似文献
4.
《滨州学院学报》2022,(2):5-12
为提高逆流控制矢量喷管的气动性能,提出一种逆流控制矢量喷管的引射设计方案,在喷管外套管尾部沿切线方向引入一股射流,通过改变外套管内部流场及高速气流的卷吸作用,提高整个喷管的推力矢量角。运用数值模拟的方法,对原型喷管与引射式喷管(称为改进型喷管)在相同设计工况下进行计算,先后得到了流场的压力系数、马赫数、流线等分布情况并进行分析。研究表明：引射会对推力矢量角及推力系数产生影响,与同等工况下的原型喷管相比较,改进型喷管的矢量角提高2.89°,推力系数提高0.72%;引射会增大主流两侧压差,同时对主流卷吸使其向上偏转;当引射压强增大时,改进型喷管主流两侧的压差也会随之增大,从而提高推力矢量角。 相似文献
5.
以自主设计的空气静压型快刀伺服系统作为研究对象,建立空气静压导轨的气体润滑基本方程,推导三维稳态Reynolds方程,获得空气静压导轨的承载力和刚度方程.通过FLUENT软件进行CFD仿真,研究空气静压导轨的供气压力、气膜厚度与承载力、刚度的影响关系.结果表明,为获得较强承载力和刚度,气膜设计厚度一般为15～25μm.... 相似文献
6.
基于FLUENT软件对制冷剂R134a在水平螺旋槽管管外沸腾换热进行了三维数值模拟,得到了其饱和泡状沸腾过程中体积含汽率的分布规律和换热系数,并和光管进行了比较。结果表明螺旋槽管外侧能够很好地强化沸腾传热。此外,还通过改变边界条件分析了质量流量、热流密度的变化对螺旋管管外沸腾换热系数的影响。 相似文献
7.
8.
曾岳凯 《商情·科学教育家》2013,(26)
为了探究新型复合竹层积材在木结构中的实际应用性,填补其横纹销槽承压强度的计算公式.本文进行了7个测试组,每组4个重复试件,共28个竹层积材横纹销槽承压试件的试验研究,分析了竹层积材厚度、端距和销直径等因素对竹层积材销槽承压的刚度、屈服载荷、屈服位移和承压强度等力学性能的影响.研究表明:承压强度随竹层积材厚度的增加,先增加后减小;端距对承压强度的影响较小,可忽略不计;承压强度随销直径的增加,大致呈线性递减.通过回归拟合的竹层积材厚度的影响系数、销直径的影响系数,建立了竹层积材横纹销槽承压强度的理论计算公式,且理论计算结果与实测结果吻合良好. 相似文献
9.
采用有限元分析方法考察梁和柱的截面尺寸、角型连接件尺寸、铆钉直径及端距等对节点性能的影响,根据计算得到的弯矩-转角曲线拟合出三参数模型中形状系数n 值的近似计算公式。结果表明,柱翼缘厚度和角型件厚度对节点初始刚度和极限承载力影响显著,梁高和铆钉端距的影响次之。形状系数建议公式计算结果与试验结果吻合较好,可为该类连接节点设计方法提供理论依据。 相似文献
10.
为了提高叶栅的气动性能,通过研究叶栅流场的流动结构改变几何参数以达到对叶栅进行流动控制的目的。该研究在原有干净叶栅的尾缘附近从下翼面到上翼面之间开了一个通槽,利用CFD商用软件数值模拟了干净叶栅和开槽叶栅在不同雷诺数下的气动性能,分析了雷诺数对二者气动性能的影响以及流场结构。研究表明:在低雷诺数下,这种槽道结构能够提高叶栅的总压损失系数同时适当的增大气流转折角;随着雷诺数的继续增加,在高雷诺数下槽道结构对叶栅的气动性能提高有限。 相似文献
11.
Cubic Spline Solutions of Nonlinear Bending and Buckling of Circular Plates with Arbitrarily Variable Thickness 总被引：2，自引：0，他引：2
The cubic B-splines taken as trial function, the large deflection of a circular plate with arbitrarily variable thickness,as well as the buckling load, have been calculated by the method of point collocation. The support can be elastic. Loads imposed can be polynomial distributed loads, uniformly distributed radial forces or moments along the edge respectively or their combinations. Convergent solutions can still be obtained by this method under the load whose value is in great excess of normal one. Under the action of the uniformly distributed loads, linear solutions of circular plates with linearly or quadratically variable thickness are compared with those obtained by the parameter method. Buckling of a circular plate with identical thickness beyond critical thrust is compared with those obtained by the power series method. 相似文献
12.
A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area. 相似文献
13.
倪振利 《石家庄铁路工程职业技术学院学报》2014,(2):74-77
盾构机是城市地铁和隧道施工的主要机械装备,盾构机各项参数的设定对于掘进速度和施工质量影响重大。从盾构机刀盘扭矩和转速、千斤顶总推力、推进速度、螺旋输送机转速和压力、注浆流量和压力、加泥加泡沫流量和压力等参数分析入手,详细分析各项参数的设置对掘进性能的影响。并以北京地铁盾构施工为例,设计各项参数优化的具体实现思路,为盾构施工的科学组织和优化管理提供理论指导。 相似文献
14.
The pressure increasing process within a twin screw multiphase pump, under the condition of high gas volume fractions (GVFs),
induces large temperature and pressure changes that cause the rotors to deform. Rotor deformations heavily influence the backflow
of the multiphase fluid through clearances within the twin screw multiphase pump and these deformations may even lead to pump
failures. An accurate temperature and pressure distribution on the screw rotors need be obtained before the deformation analysis
can be carried out. By means of small temperature and pressure sensors embedded into the groove at the root of the rotors,
the temperatures of 12 points on the rotors and the pressure distributions of a twin screw multiphase pump under high GVFs
conditions were recorded. Temperature test results were adopted to perform a heat transfer analysis for determining the temperature
distribution on the screw rotors. Then deformation analyses, including thermal deformation, force deformation, and total deformation,
were conducted according to the pressure and temperature distributions. Deformation analysis for different materials was also
conducted under the same boundary conditions. A material was suggested for the manufacturing of rotors in a twin screw multiphase
pump under the condition of high gas volume fractions. 相似文献
15.
New numerical solution for self-acting gas journal bearings 总被引：1，自引：0，他引：1
Taking a small pressure change in the gas film of self-acting gas-lubricated journal bearings into account, the corresponding nonlinear Reynolds equation is linearized through appropriate approximation and a modified Reynolds equation is derived and solved by means of the finite difference method （FDM）. The gas film pressure distribution of a self-acting gas-lubricated journal bearing is attained and the load capacity is calculated. The numerical solution has a better agreement with experimental data than a direct numerical solution for different values of the bearing number. It is of interest to note that the eccentricity ratio, at which the new numerical solution is in better agreement with experimental data, is different when the bearing number is changing. The new numerical solution is slightly larger when the eccentricity ratio is smaller, and becomes slightly smaller when the eccentricity ratio is larger. 相似文献
16.
A quasi 1D model of two-phase flow for a urea-selective catalytic reduction (SCR) system is developed which can calculate not only the generation of reducing agent but also the formation of deposits in the exhaust pipe. The gas phase flow is solved through Euler method, variables are stored on staggered grids, and the semi-implicit method for pressure-linked equation (SIMPLE) algorithm is applied to decouple the pressure and velocity. The liquid phase is treated in a Lagrangian way, which solves the equations of droplet motion, evaporation, thermolysis, and spray wall interaction. A combination of a direct decomposition model and a kinetic model is implemented to describe the different decomposition behaviors of urea in the droplet phase and wall film, respectively. A new 1D wall film model is proposed, and the equations of wall film motion, evaporation, thermolysis, and species transport are solved. The position, weight, and components of deposits can be simulated following implementation of the semi-detailed kinetic model. The simulation results show that a decrease in the exhaust temperature will increase the wall film region and the weight of deposits. Deposit components are highly dependent on temperature. The urea-water-solution (UWS) injection rate can affect the total mass of wall film and expand the film region, but it has little influence on deposit components. An increase in exhaust mass flow can decrease the total weight of deposits on the pipe wall because of the promotion of the mass and heat transfer process both in the droplets and wall film. 相似文献
17.
开发了一套可在控温、控湿环境中开展不同形态薄层液膜下CO2腐蚀测试的实验装置,以适应薄层液膜下的CO2腐蚀机制及规律研究需求。实验装置主要由环境控制系统、液膜厚度测量系统和腐蚀电化学测试系统组成。环境控制系统主体为有机玻璃做成的密闭环境腔,既可以开展控温、控湿以及承压环境下的实验测试,同时又可方便地观察腔体内情况。薄层液膜形态包括不同厚度的均一液膜和存在厚度梯度的不均一液膜,由液膜厚度测量系统获得不同液膜形态下的CO2腐蚀行为。结果表明:金属CO2腐蚀速率随液膜厚度的不同而不同,液膜厚度相同但均一性不同时,CO2腐蚀行为也存在差异。 相似文献
18.
AWAD Samir Hamid 《重庆大学学报(英文版)》2005,4(1)
1 Introduction Weight saving materials such as aluminum and its alloys are becoming increasingly important and have been attracting increasing attention over the past decade, specially in the automotive, aerospace and chemical industries, and electrical devices because of their high strength-to-weight ratio, high electrical and thermal conductivities, processability and recyclability and good resistance to degradation in some corrosive environments [1,2]. In the automotive industry, there is d… 相似文献
19.
Mechanical model of domestic gas explosion load 总被引：3，自引：0，他引：3
With the increase of domestic gas consumption in cities and towns in China,gas explo-sion accidents happened rather frequently,and many structures were damaged greatly.Rational physical design could protect structures from being destroyed,but the character of explosion load must be learned firstly by establishing a correct mechanical model to simulate vented gas explo-sions.The explosion process has been studied for many years towards the safety of chemical in-dustry equipments.The key problem of these studies was the equations usually involved some ad-justable parameters that must be evaluated by experimental data,and the procedure of calculation was extremely complicated,so the reliability of these studies was seriously limited.Based on these studies,a simple mathematical model was established in this paper by using energy conservation,mass conservation,gas state equation,adiabatic compression equation and gas venting equation.Explosion load must be estimated by considering the room layout; the rate of pressure rise was then corrected by using a turbulence factor,so the pressure-time curve could be obtained.By using this method,complicated calculation was avoided,while experimental and calculated results fitted fairly well.Some pressure-time curves in a typical rectangular room were calculated to inves-tigate the influences of different ignition locations,gas thickness,concentration,room size and venting area on the explosion pressure.The results indicated that: it was the most dangerous con-dition when being ignited in the geometry centre of the room; the greater the burning velocity,the worse the venting effect; the larger the venting pressure,the higher the peak pressure; the larger the venting area,the lower the peak pressure. 相似文献