CN103226634A - Computing method for unsteady flow field of rotary jet pump based on three-dimensional dynamic mesh - Google Patents

Computing method for unsteady flow field of rotary jet pump based on three-dimensional dynamic mesh Download PDF

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CN103226634A
CN103226634A CN2013101383374A CN201310138337A CN103226634A CN 103226634 A CN103226634 A CN 103226634A CN 2013101383374 A CN2013101383374 A CN 2013101383374A CN 201310138337 A CN201310138337 A CN 201310138337A CN 103226634 A CN103226634 A CN 103226634A
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黄思
杨富翔
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South China University of Technology SCUT
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Abstract

本发明提供了一种基于三维动网格的旋喷泵非定常流场的计算方法,应用于旋喷泵技术领域,该方法基于三维动网格技术,解决了网格重构的技术问题,实现了旋喷泵的非定常流场计算。

Figure 201310138337

The invention provides a calculation method for the unsteady flow field of a rotary jet pump based on a three-dimensional dynamic grid, which is applied in the technical field of a rotary jet pump. The method is based on a three-dimensional dynamic grid technology and solves the technical problem of grid reconstruction. The calculation of the unsteady flow field of the rotary jet pump is realized.

Figure 201310138337

Description

基于三维动网格的旋喷泵非定常流场的计算方法Calculation method of unsteady flow field of rotary jet pump based on 3D dynamic mesh

技术领域technical field

本发明涉及旋喷泵技术领域,更具体地说,涉及一种用于旋喷泵的非定常流场的计算方法。The invention relates to the technical field of a rotary jet pump, in particular to a calculation method for an unsteady flow field of a rotary jet pump.

背景技术Background technique

小流量高扬程泵在石油、化工、城建、冶金、造纸等诸多行业中有着广泛的应用。该类泵的比转速很低(ns≤30),因此带来的问题是水泵运行效率偏低,能量损耗极其严重。旋喷泵(又称旋转喷射泵、毕托泵)是基于毕托管将流体动能转换成势能原理研制的一种低比转速泵。图1是旋喷泵的流动模型,它包括进水段、叶轮、转子腔和集流管四个主要过流部件,其中叶轮和转子腔固接在一起并随主轴同步旋转,而集流管则是插入转子腔内的静止元件。旋喷泵运行时,液体从进水段进入叶轮,受旋转叶轮叶片作用后获得能量进入转子腔,再随转子腔一起转动获得更高的动能后进入集流管,经过扩散段动能转换为势能后由集流管的直管段流出。与常规的高压泵(如多级泵、往复泵等)相比,旋喷泵具有结构简单、体积小、重量轻、使用方便、工作可靠等特点,逐渐成为小流量高扬程泵的主要选项,在泵效率等性能方面也有较大的提升潜力。从应用的角度讲,如图1所示,集流管的径向长度与转子腔半径相当,集流管的横截面直径约占转子腔轴向尺寸的1/4~1/3。可以想象,当叶轮和转子腔旋转时,固定静止的集流管必然对高速旋转(部分旋喷泵转速在4000rpm以上)的叶轮和转子腔流场产生严重的干扰,集流管本身周围也形成压差产生对集流管较大的作用力,引发振动噪音等不利因素。Low-flow high-lift pumps are widely used in many industries such as petroleum, chemical industry, urban construction, metallurgy, and papermaking. The specific speed of this type of pump is very low (ns≤30), so the problem is that the operation efficiency of the pump is low and the energy loss is extremely serious. Rotary jet pump (also known as rotary jet pump, Pitot pump) is a low specific speed pump developed based on the principle of converting fluid kinetic energy into potential energy by Pitot tube. Figure 1 is the flow model of the rotary jet pump, which includes four main flow-passing components: the water inlet section, the impeller, the rotor chamber and the manifold, where the impeller and the rotor chamber are fixed together and rotate synchronously with the main shaft, while the manifold It is a stationary element inserted into the rotor cavity. When the rotary jet pump is running, the liquid enters the impeller from the water inlet section, gets energy from the blades of the rotating impeller, enters the rotor cavity, and then rotates with the rotor cavity to obtain higher kinetic energy, then enters the header, and converts the kinetic energy into potential energy through the diffusion section Then it flows out from the straight pipe section of the collector. Compared with conventional high-pressure pumps (such as multi-stage pumps, reciprocating pumps, etc.), rotary jet pumps have the characteristics of simple structure, small size, light weight, convenient use, and reliable operation, and have gradually become the main option for low-flow high-lift pumps. There is also a large potential for improvement in performance such as pump efficiency. From the perspective of application, as shown in Figure 1, the radial length of the collector is equivalent to the radius of the rotor cavity, and the cross-sectional diameter of the collector accounts for about 1/4 to 1/3 of the axial dimension of the rotor cavity. It is conceivable that when the impeller and the rotor cavity rotate, the fixed and stationary manifold will inevitably cause serious interference to the flow field of the impeller and rotor cavity rotating at high speed (some rotary jet pumps rotate at speeds above 4000rpm), and there will also be formation around the manifold itself. The pressure difference produces a large force on the collector, causing unfavorable factors such as vibration and noise.

从科学研究的角度讲,对于普通叶片泵(如离心泵、轴流泵等)的非定常流动问题,当叶轮旋转时,转子(叶轮)域与定子(泵体、管路)域几何形状始终保持不变;除了相连接的交界面外,转子域与定子域各自独立、互不干涉,因此可采用都是刚性网格的转子域和定子域做相对运动的“滑移网格法”进行瞬态分析。但在旋喷泵流场中,当转子(转子腔和叶轮)域旋转时,转子域与静止的集流管实体发生冲突;若要避开集流管实体的干涉,转子计算域必须随时间做大幅变形,计算网格也需要做相应的调整,因此不能使用上述刚性网格的“滑移网格法”。From the perspective of scientific research, for the unsteady flow problem of ordinary vane pumps (such as centrifugal pumps, axial flow pumps, etc.), when the impeller rotates, the geometric shapes of the rotor (impeller) domain and the stator (pump body, pipeline) domain are always the same. remain unchanged; except for the connected interface, the rotor domain and the stator domain are independent and do not interfere with each other, so the "slip grid method" in which the rotor domain and the stator domain are both rigid grids do relative motion can be used for transient analysis. However, in the flow field of the jet pump, when the rotor (rotor chamber and impeller) domain rotates, the rotor domain conflicts with the stationary manifold entity; to avoid the interference of the manifold entity, the rotor calculation domain must change with time For large deformations, the calculation grid also needs to be adjusted accordingly, so the above-mentioned "slip grid method" for rigid grids cannot be used.

解决流动域及网格的大变形问题,必须采取三维计算旋转域及其网格重构技术,才有可能实现旋喷泵的非定常流场分析。由于三维网格重构的复杂性、计算耗时及新旧网格多次映射插值引起误差等多方面的原因,到目前为止基于三维网格重构技术的流场分析尚处于探索阶段,更没有成熟的工程应用案例。To solve the problem of large deformation of the flow domain and grid, it is necessary to adopt three-dimensional calculation of the rotating domain and its grid reconstruction technology, so that it is possible to analyze the unsteady flow field of the rotary jet pump. Due to the complexity of 3D mesh reconstruction, time-consuming calculation, and errors caused by multiple mapping interpolation of old and new meshes, so far the flow field analysis based on 3D mesh reconstruction technology is still in the exploratory stage, let alone Mature engineering application cases.

1923年Krogh把毕托管工作原理应用到泵的设计中,后被研制成旋喷泵用于二战。20世纪80年代,德国、日本等国投入资金进行旋喷泵的理论研究和产品开发,目前已有很多产品投入市场,但可查阅的旋喷泵资料大都是产品介绍,相关的研究报导和技术资料还很少见。90年代中,Sbom对旋喷泵的工作原理、结构特点及其应用等方面做了全面的介绍。In 1923, Krogh applied the Pitot tube working principle to the design of the pump, which was later developed into a rotary jet pump for World War II. In the 1980s, Germany, Japan and other countries invested in the theoretical research and product development of rotary jet pumps. At present, many products have been put into the market, but most of the available rotary jet pump materials are product introductions, related research reports and technical reports. Information is still rare. In the mid-1990s, Sbom made a comprehensive introduction to the working principle, structural characteristics and applications of the rotary jet pump.

20世纪80年代末我国陆续引进旋喷泵产品,国内也开始了关于旋喷泵工作原理、水力性能等方面的研究。杨军虎、齐学义、马希金等通过样机试验,分析了旋喷泵内流动状况,提出长短叶片相间的复合式叶轮设计方法,给出了集流管的设计公式和选择范围;他们还采用任意准三元正交面法求解旋喷泵叶轮内的准三元流场,并对旋喷泵的流动机理和设计方法进行了初步研究。王成木等将旋喷泵的三种叶轮与四种集流管进行了不同组合试验,发现复合式常规叶片叶轮的效率没有直叶片的叶轮效率高;还发现集流管的断面形状、尺寸和粗糙度除了对流动阻力大小有影响外,还对泵的工作稳定性产生影响。At the end of the 1980s, my country introduced rotary jet pump products one after another, and the country also started research on the working principle and hydraulic performance of rotary jet pumps. Yang Junhu, Qi Xueyi, Ma Xijin, etc. analyzed the flow conditions in the jet pump through prototype tests, proposed a composite impeller design method with alternate long and short blades, and gave the design formula and selection range of the header; they also used any quasi-ternary The quasi-three-dimensional flow field in the impeller of the rotary jet pump is solved by the orthogonal surface method, and the flow mechanism and design method of the rotary jet pump are studied preliminarily. Wang Chengmu et al. conducted different combination tests of three impellers and four headers of the rotary jet pump, and found that the efficiency of the composite conventional blade impeller was not as high as that of the straight blade impeller; it was also found that the cross-sectional shape, size and roughness of the header In addition to affecting the size of the flow resistance, the temperature also affects the working stability of the pump.

随着计算技术的快速发展,近年来一些学者相继开展了旋喷泵粘性流场的数值模拟研究。王云芸、陈次昌、杨昌明等运用Fluent软件,采用标准k-ε湍流模型及SIMPLEC算法,分析了旋喷泵叶轮内的流动规律。程云章、朱兵、陈红勋等在相对参考系下对旋喷泵叶轮和转子腔、在绝对参考系下对集流管内流动进行了三维数值模拟,模拟结果显示集流管在拐角处和截面内有明显的回流和旋涡。邹雪莲、陈红勋建立了旋喷泵直叶片叶轮的流动数学模型,对叶轮内流动进行了三维计算和对比分析。许洪元、田爱民、王晓东等对集流管内流动做了深入研究,了解了集流管内压力、流速以及湍流的分布规律,得知集流管扩散段的形状对泵效率有较大的影响。余惠琼、季全凯、符杰等对旋喷泵内流场进行了数值模拟,探讨了叶轮和集流管等有关几何参数对泵性能影响。易同祥、王春林运用ANSYS-CFX软件对旋喷泵内流场进行了大涡数值模拟,分析了集流管进口形状和翼型对泵性能的影响,分析了不同工况下固体颗粒对旋喷泵壁面的磨损情况,在不计集流管对旋转流场干涉的条件下,研究了泵内的脉动压力。宋怀德、刘宜对旋喷泵的集流管和转子腔进行了内流场的数值模拟,针对不同集流管形状、进口尺寸所构成的旋喷泵进行了研究。黄思、苏丽娟等人运用数值模拟结合性能实验,探讨了立式旋喷泵叶轮形式(单侧开式、单侧闭式和双侧开式)、叶片形状(直叶片、弯曲叶片和长短叶片组合)、叶片数、集流管外形、集流管流道截面、集流管转弯半径等参数对泵性能的影响。With the rapid development of computing technology, some scholars have carried out numerical simulation research on the viscous flow field of the jet pump in recent years. Wang Yunyun, Chen Cichang, Yang Changming, etc. used Fluent software, adopted the standard k-ε turbulence model and SIMPLEC algorithm, and analyzed the flow law in the impeller of the jet pump. Cheng Yunzhang, Zhu Bing, Chen Hongxun et al. carried out three-dimensional numerical simulation of the impeller and rotor cavity of the jet pump in the relative reference system, and the flow in the manifold in the absolute reference system. The simulation results show that the manifold has Significant backflow and swirl. Zou Xuelian and Chen Hongxun established the flow mathematical model of the straight blade impeller of the rotary jet pump, and carried out three-dimensional calculation and comparative analysis of the flow in the impeller. Xu Hongyuan, Tian Aimin, Wang Xiaodong, etc. have conducted in-depth research on the flow in the manifold, understood the distribution of pressure, flow velocity and turbulence in the manifold, and learned that the shape of the diffuser section of the manifold has a greater impact on pump efficiency. Yu Huiqiong, Ji Quankai, Fu Jie et al. carried out numerical simulation of the flow field in the rotary jet pump, and discussed the influence of geometric parameters such as impeller and manifold on the performance of the pump. Yi Tongxiang and Wang Chunlin used ANSYS-CFX software to carry out large eddy numerical simulation of the flow field in the rotary jet pump, analyzed the influence of the shape of the inlet of the manifold and the airfoil on the performance of the pump, and analyzed the impact of solid particles on the rotary jet pump under different working conditions. The wear condition of the wall surface of the jet pump was studied, and the pulsating pressure in the pump was studied under the condition that the collecting pipe interfered with the rotating flow field. Song Huaide and Liu Yi carried out numerical simulation of the internal flow field of the header and rotor cavity of the rotary jet pump, and studied the rotary jet pumps with different header shapes and inlet sizes. Huang Si, Su Lijuan and others used numerical simulation combined with performance experiments to discuss the impeller forms (one-side open, one-side closed and double-side open), blade shapes (straight blades, curved blades, and long and short blades) of vertical jet pumps. Combination), the number of blades, the shape of the manifold, the cross section of the manifold, the turning radius of the manifold and other parameters on the performance of the pump.

由于之前提到的因集流管实体干涉,造成转子计算域和计算网格必须随时间做大幅变形调整问题,因此上述旋喷泵的流场计算只能局限于定常的计算,即对转子域(叶轮和转子腔)采取了“转子冻结法”:转子域与定子域(集流管)都是刚性的,它们之间没有相对运动。显然,定常模拟是不能反映旋喷泵的瞬时流动状况的,尤其是固定集流管对高速旋转的叶轮和转子腔流场产生严重干扰,集流管自身周围也形成压差产生对集流管较大的作用力并可能引发振动噪音的现象。Due to the previously mentioned problem that due to the interference of the manifold entity, the calculation domain and the calculation grid of the rotor must be greatly deformed and adjusted over time, so the flow field calculation of the above-mentioned rotary jet pump can only be limited to the steady calculation, that is, for the rotor domain (Impeller and rotor cavity) adopted the "rotor freezing method": both the rotor domain and the stator domain (manifold) are rigid, there is no relative motion between them. Obviously, the steady state simulation cannot reflect the instantaneous flow conditions of the rotojet pump, especially the fixed header will seriously interfere with the high-speed rotating impeller and the flow field of the rotor chamber, and the pressure difference around the header itself will also generate pressure on the header. Large force and may cause vibration noise phenomenon.

关于水力机械的非定常计算方法,水力机械的非定常流动问题大致可分为以下3类:(1)物体静止而流动为非定常问题,如静止叶栅的分离流动等;(2)单个物体作刚性运动的非定常流动问题,如转子绕轴的转动等;(3)多体作相对运动或变形运动的非定常问题,如齿轮泵啮合、阀门的开启关闭、活塞在缸中的往复运动等等。With regard to the unsteady calculation method of hydraulic machinery, the unsteady flow problems of hydraulic machinery can be roughly divided into the following three categories: (1) the object is stationary but the flow is unsteady, such as the separation flow of stationary cascades, etc.; (2) a single object Unsteady flow problems with rigid motion, such as the rotation of the rotor around the shaft, etc.; (3) Unsteady problems with relative motion or deformation motion of multiple bodies, such as gear pump meshing, valve opening and closing, and piston reciprocating motion in the cylinder etc.

对于上述的第(1)类非定常问题,静态的刚性网格就能满足要求。对于第(2)类非定常问题,仍可采用静态的刚性网格,但需选取非惯性系或多参考系(惯性系+非惯性系)进行定常或非定常计算。例如,对于水力机械最常见的转子流动问题。因为转子是周期性的掠过求解域,对于惯性系讲,流动是非定常的。然而在不考虑静止部件的情况下,取旋转部件一起运动的计算域在旋转参考系(非惯性系)下,流动则可视为定常的,使问题得到了简化。如果除了旋转部件,也要考虑静止部件的话,如在涡轮中同时有转子和定子的流动问题,这种情况就必须采用多参考系(Multiple Reference Frame,简称MRF)进行分析。采用静止的刚性网格,可省去使用动网格计算所带来的诸多麻烦(如几何守恒率、运动边界等),因此绝大部分CFD软件都集成了多参考系MRF技术。但必须指出的是,MRF系下转子与定子的位置关系仅仅是某一时刻它们之间的相互位置,称之为“转子冻结法”(Frozen Rotor Approach)。很明显,转子冻结法不能解决因转子与定子作相对运动所引起的非定常流动问题。For the unsteady problems of type (1) mentioned above, a static rigid grid can meet the requirements. For unsteady problems of type (2), static rigid grids can still be used, but non-inertial frames or multiple reference frames (inertial frames + non-inertial frames) need to be selected for steady or unsteady calculations. For example, the most common rotor flow problem for hydraulic machinery. The flow is unsteady for an inertial frame because the rotor is periodically grazing the solution domain. However, in the case of not considering the stationary components, the calculation domain that moves with the rotating components is in the rotating reference frame (non-inertial frame), and the flow can be regarded as steady, which simplifies the problem. If stationary components are also considered in addition to rotating components, such as the flow problem of both rotor and stator in the turbine, this situation must be analyzed using Multiple Reference Frame (MRF for short). Using a static rigid grid can save many troubles (such as geometric conservation rate, motion boundary, etc.) caused by using dynamic grid calculations. Therefore, most CFD software integrates multi-reference frame MRF technology. However, it must be pointed out that the positional relationship between the rotor and the stator under the MRF system is only the mutual position between them at a certain moment, which is called the "Frozen Rotor Approach". Obviously, the rotor freezing method cannot solve the unsteady flow problem caused by the relative motion of the rotor and the stator.

对于第(3)类非定常问题,涉及到物体的相对运动或变形,常见的解决办法有滑移网格和动网格等方法。滑移网格的基本思想是在运动部件的运动轨迹周围预先划出一个滑移子域。在滑移子域与其他区域的交界面处,利用边界条件与其他区域对接,从而实现整体流场的计算。滑移网格技术严格来说属于刚性运动网格的一种。在整个运动过程中,计算网格随物体按已知的运动方式一起作刚体运动,计算网格无须重新生成,因此计算量小,并可保持初始网格的质量。滑移网格技术在常规的旋转叶轮机械、车辆交会等非定常流动问题中应用广泛,Ansys-CFX、Fluent等CFD软件中也集成了该网格技术。但滑移网格法不能解决变形体或多体相对运动等复杂问题,而旋喷泵转子域正是属于变形体一类。For the type (3) unsteady problems involving relative motion or deformation of objects, common solutions include sliding mesh and moving mesh. The basic idea of the slip mesh is to pre-draw a slip subdomain around the motion trajectory of the moving part. At the interface between the slip subdomain and other regions, the boundary conditions are used to connect with other regions, so as to realize the calculation of the overall flow field. Sliding mesh technology is strictly a kind of rigid moving mesh. During the whole movement process, the computational mesh performs rigid body motion together with the object in a known motion mode, and the computational mesh does not need to be regenerated, so the calculation amount is small, and the quality of the initial mesh can be maintained. Slip grid technology is widely used in unsteady flow problems such as conventional rotating impeller machinery and vehicle intersection, and this grid technology is also integrated in CFD software such as Ansys-CFX and Fluent. However, the sliding mesh method cannot solve complex problems such as deformable bodies or relative motions of multiple bodies, and the rotor domain of the rotary jet pump belongs to the category of deformable bodies.

理论上讲,动网格方法是解决非定常流动问题的通用办法,一般用来解决流场形状由于边界运动而随时间改变的问题。边界的运动方式可以是预先已知的,也可以是预先未知的,即边界的运动要由前一步的计算结果决定,网格的更新则根据边界的变化情况自动完成。动网格方法的基本思想是在每个时间步内,通过对流体域的网格更新以实现由于边界运动而引起的求解域的变化,采用任意拉格朗日—欧拉(ALE)方法描述流体运动的控制方程,新网格的物理量通过插值运算从旧网格映射得到,并对每个时间步网格上的物理量进行迭代求解,以此来获得流动的动态演化结果。Theoretically speaking, the moving mesh method is a general method to solve unsteady flow problems, and is generally used to solve the problem that the shape of the flow field changes with time due to boundary motion. The movement mode of the boundary can be known or unknown in advance, that is, the movement of the boundary is determined by the calculation result of the previous step, and the update of the grid is automatically completed according to the change of the boundary. The basic idea of the dynamic grid method is to update the grid of the fluid domain in each time step to realize the change of the solution domain due to boundary motion, and use the arbitrary Lagrangian-Eulerian (ALE) method to describe The governing equation of fluid motion, the physical quantities of the new grid are mapped from the old grid through interpolation operations, and the physical quantities on the grid of each time step are iteratively solved to obtain the dynamic evolution results of the flow.

常见的动网格方法有以下三种:基于弹簧理论的弹簧光滑法(Spring-basedsmoothing)、动态分层法(Dynamic layering)以及网格重构法(Remeshing)。There are three common dynamic grid methods: Spring-based smoothing, Dynamic layering and Remeshing based on spring theory.

(l)弹簧光滑法是将各网格边简化为具有一定刚度并通过节点连接的弹簧。以边界位移量作为弹簧的边界条件,通过求解弹簧系统的力平衡方程得到节点的位移增量,最终得到新网格的节点位置。弹簧光滑法中新旧网格节点的拓扑关系保持不变,因此能够保证计算精度。但弹簧光滑法通过改变网格节点位置来拉伸或压缩网格,容易造成网格过密或过疏;当计算域变形较大时,变形后的网格会产生较大的倾斜度使网格质量恶化、影响计算精度;严重时甚至出现负体积网格,使计算出错而终止。(l) The spring smoothing method simplifies each grid edge into a spring with a certain stiffness and connected by nodes. Taking the boundary displacement as the boundary condition of the spring, the displacement increment of the node is obtained by solving the force balance equation of the spring system, and finally the node position of the new grid is obtained. In the spring smoothing method, the topological relationship of the old and new grid nodes remains unchanged, so the calculation accuracy can be guaranteed. However, the spring smoothing method stretches or compresses the grid by changing the position of the grid nodes, which may easily cause the grid to be too dense or too sparse; The grid quality deteriorates and affects the calculation accuracy; in severe cases, even negative volume grids appear, which makes the calculation error and terminated.

(2)动态分层法是根据边界的位移量动态地增加或减少边界上的网格层,即先在边界上假定一个理想的网格层高度,在边界发生运动时,如果紧邻边界的网格层高度同理想高度相比拉伸到一定程度时,就将其分为两个网格层;如果临近网格被压缩到一定程度时,就将紧邻边界的两个网格层合并为一个层,使边界上的网格层保持一定的密度。动态分层法在生成网格时速度较快,但它要求运动边界附近的网格为六面体(三维),这对于复杂外形的流动域来说是不适合的。(2) The dynamic layering method is to dynamically increase or decrease the grid layer on the boundary according to the displacement of the boundary, that is, first assume an ideal grid layer height on the boundary, and when the boundary moves, if the grid layer next to the boundary When the height of the grid layer is stretched to a certain extent compared with the ideal height, it will be divided into two grid layers; if the adjacent grid is compressed to a certain extent, the two grid layers adjacent to the boundary will be merged into one layer to maintain a certain density on the mesh layer on the boundary. The dynamic layering method is faster in generating meshes, but it requires the meshes near the motion boundary to be hexahedral (three-dimensional), which is not suitable for flow domains with complex shapes.

(3)网格重构法是对弹性光滑法的补充,弹性光滑法一般只能处理小变形流场问题。对于水力机械的某些问题,如齿轮泵啮合、阀门开关过程等问题,大变形不可避免。因此,需要利用网格重构法对流场网格进行重新划分。网格重构法是以网格尺寸和畸变率等作为评判标准,当边界的移动和变形过大,局部网格发生严重畸变时,则对这些区域重新划分网格。新网格上的物理量通过体积守恒定律和插值映射从旧网格中获得。需要说明的是,网格重构法在每次变形移动时都需要重新划分网格,因而耗费较多的计算时间。(3) The mesh reconstruction method is a supplement to the elastic smoothing method, and the elastic smoothing method can generally only deal with small deformation flow field problems. For some problems of hydraulic machinery, such as gear pump meshing, valve switching process, etc., large deformation is inevitable. Therefore, it is necessary to use the mesh reconstruction method to re-divide the flow field mesh. The grid reconstruction method uses the grid size and distortion rate as the evaluation criteria. When the movement and deformation of the boundary are too large, and the local grid is severely distorted, the grid is re-divided for these areas. The physical quantities on the new grid are obtained from the old grid by volume conservation laws and interpolation mapping. It should be noted that the mesh reconstruction method needs to re-mesh every time the deformation moves, thus consuming more calculation time.

目前动网格技术在水力机械的应用主要是偏心泵或齿轮泵的转动、阀门的开启与关闭过程、活塞在缸中的往复运动等三个方面。这些工作的一般做法是在流动软件中使用动边界文件(Profile)或用户自定义函数(User-DefinedFunction,简称UDF)来定义已知的齿轮、阀芯或活塞等动边界的运动方式,采用动网格技术(弹簧光滑法、动态分层法以及网格重构法)对计算域内的非定常流动状态进行模拟计算、可视化分析,得出流场与受力随时间的变化情况。但动网格技术在推广到三维网格变形时,不仅算法复杂性增加、网格变形效率降低,而且变形后的网格质量往往不理想而导致计算终止,因此上述动网格技术应用基本局限于二维(如在齿轮泵模型中,近似认为流动参数在旋转轴方向没有变化;在阀门启闭、缸中活塞往复运动中做轴对称假设)或准三维(由二维域在轴向拉伸成为三维域)的简化模型计算。At present, the application of dynamic grid technology in hydraulic machinery is mainly in three aspects: the rotation of eccentric pump or gear pump, the opening and closing process of valves, and the reciprocating motion of piston in cylinder. The general practice of these tasks is to use a dynamic boundary file (Profile) or a user-defined function (User-Defined Function, referred to as UDF) in the flow software to define the known movement of the dynamic boundary of the gear, spool or piston. Grid technology (spring smoothing method, dynamic layering method and grid reconstruction method) performs simulation calculation and visual analysis on the unsteady flow state in the calculation domain, and obtains the change of flow field and force with time. However, when the dynamic mesh technology is extended to 3D mesh deformation, not only the complexity of the algorithm increases and the efficiency of mesh deformation decreases, but also the quality of the deformed mesh is often unsatisfactory and the calculation is terminated. Therefore, the application of the above dynamic mesh technology is basically limited. In two-dimensional (such as in the gear pump model, it is approximately considered that the flow parameters do not change in the direction of the axis of rotation; axisymmetric assumptions are made in the opening and closing of the valve and the reciprocating motion of the piston in the cylinder) or quasi-three-dimensional (the two-dimensional domain is drawn in the axial direction extended into a three-dimensional domain) for simplified model calculations.

综上所述,由于旋喷泵静止的集流管严重干涉了转子域,因此目前所有旋喷泵的流场分析只能是建立在转子冻结法的定常计算基础上,旋喷泵的非定常流场计算至今仍是空白。To sum up, because the static header of the rotary jet pump seriously interferes with the rotor domain, the flow field analysis of all current rotary jet pumps can only be based on the steady calculation of the rotor freezing method, and the unsteady calculation of the rotary jet pump Flow field calculation is still blank.

发明内容Contents of the invention

本发明的目的在于克服现有技术的不足,提供一种基于三维动网格的旋喷泵非定常流场的计算方法,该方法基于三维动网格技术,解决了网格重构的技术问题,实现了旋喷泵的非定常流场计算。The purpose of the present invention is to overcome the deficiencies of the prior art and provide a calculation method for the unsteady flow field of a rotary jet pump based on a three-dimensional dynamic grid. The method is based on a three-dimensional dynamic grid technology and solves the technical problem of grid reconstruction , the calculation of the unsteady flow field of the rotary jet pump is realized.

为了达到上述目的,本发明采用如下的技术方案:基于三维动网格的旋喷泵非定常流场的计算方法,其特征在于,包括如下步骤:In order to achieve the above object, the present invention adopts the following technical scheme: the calculation method of the unsteady flow field of the rotary jet pump based on the three-dimensional dynamic grid, it is characterized in that, comprises the following steps:

第一步,将旋喷泵中转子腔、叶轮、进水段和集流管定义为计算域,其中,转子腔和叶轮定义为计算域中的旋转域,使用机械制图软件构造计算域的三维实体,形成三维实体文件;In the first step, the rotor cavity, impeller, water inlet section and header in the jet pump are defined as the calculation domain, in which the rotor cavity and the impeller are defined as the rotation domain in the calculation domain, and the three-dimensional calculation domain is constructed using mechanical drawing software Entity, forming a three-dimensional entity file;

第二步,使用网格划分软件读取三维实体文件,对计算域进行网格划分,得到三维的初始网格,形成网格文件;The second step is to read the 3D entity file by using the meshing software, mesh the computational domain, obtain the 3D initial mesh, and form a mesh file;

第三步,使用计算流体动力学软件读取网格文件,并进行物性参数设置;所述物性参数设置包括运动边界的设置;所述运动边界的设置是指,运动边界的界面设置为流体与转子腔和叶轮所接触的表面,运动规律设置为绕轴转动,运动方式设置为Profile方式;The third step is to use computational fluid dynamics software to read the grid file, and to set the physical parameter setting; the physical parameter setting includes the setting of the motion boundary; the setting of the motion boundary means that the interface of the motion boundary is set as fluid and The contact surface between the rotor cavity and the impeller, the motion rule is set to rotate around the axis, and the motion mode is set to Profile mode;

第四步,使用计算流体动力学软件,依次对计算周期中各个时间步的数值进行计算;每个时间步的数值计算在计算所得的数值收敛后完成;当一个时间步的数值计算完成后,通过更新旋转域网格和临近旋转域部分的网格节点,重构下一时间步网格,重构下一时间步网格采用两种方案:(1)对网格尺寸和畸变率在容许范围内的区域,先采用弹簧光滑法得到下一时间步的网格节点,然后通过插值运算从现有网格得到下一时间步网格的物理量,从而重构下一时间步的网格;(2)对网格尺寸和畸变率超出容许范围的区域,重新划分网格作为下一时间步网格;下一时间步网格重构后,计算下一时间步的数值,直到完成最后时间步的计算。The fourth step is to use computational fluid dynamics software to calculate the values of each time step in the calculation cycle in turn; the numerical calculation of each time step is completed after the calculated value converges; when the numerical calculation of a time step is completed, By updating the grid of the rotation domain and the grid nodes adjacent to the rotation domain, the grid of the next time step is reconstructed. There are two schemes for reconstructing the grid of the next time step: (1) The grid size and distortion rate are within the tolerance In the area within the range, first use the spring smoothing method to obtain the grid node of the next time step, and then obtain the physical quantity of the grid of the next time step from the existing grid through interpolation operation, so as to reconstruct the grid of the next time step; (2) For the area where the grid size and distortion rate exceed the allowable range, the grid is re-divided as the grid of the next time step; after the grid reconstruction of the next time step, the value of the next time step is calculated until the last time step is completed step calculation.

由于旋喷泵结构的特殊性,目前国内外关于旋喷泵的流场计算只能采用“转子冻结”的定常方法,而关于旋转叶轮机械非定常流场计算的通用办法是采用“滑移网格法”,但该方法仍不能解决旋喷泵流场的非定常计算;本发明方法采取了旋转域与刚性域相结合的计算策略,基于三维网格,采用弹簧光滑法结合局部网格重构法实现网格重建,计算各个时间步的数值,实现了旋喷泵的非定常流场计算,为旋喷泵的瞬态流动特性分析提供有力工具。Due to the particularity of the structure of the rotary jet pump, the current calculation of the flow field of the rotary jet pump at home and abroad can only use the steady method of "rotor freezing", while the general method for the calculation of the unsteady flow field of the rotary impeller machine is to use the "slip net Grid method", but this method still cannot solve the unsteady calculation of the flow field of the jet pump; the method of the present invention adopts the calculation strategy of combining the rotating domain and the rigid domain, based on the three-dimensional grid, using the spring smoothing method combined with the local grid weight The construction method realizes grid reconstruction, calculates the value of each time step, realizes the unsteady flow field calculation of the jet pump, and provides a powerful tool for the analysis of the transient flow characteristics of the jet pump.

进一步的方案是:所述第四步中的采用弹簧光滑法得到下一时间步的网格节点是指,对网格尺寸和畸变率在容许范围内的区域,采取弹簧光滑法,将该区域的网格边简化为具有一定刚度并通过网格节点连接的弹簧,通过改变网格节点位置来拉伸或压缩网格;以边界移动量为弹簧的边界条件,通过求解弹簧系统的力平衡方程得到网格节点的位移增量,最终得到下一时间步的网格节点位置。A further solution is: in the fourth step, using the spring smoothing method to obtain the grid node of the next time step refers to adopting the spring smoothing method for the area where the grid size and distortion rate are within the allowable range, and the area The grid edge of the grid is simplified to a spring with a certain stiffness and connected by grid nodes, and the grid is stretched or compressed by changing the position of the grid nodes; the boundary movement is used as the boundary condition of the spring, and the force balance equation of the spring system is solved Get the displacement increment of the grid node, and finally get the grid node position in the next time step.

所述第四步中的计算周期是指,旋转域旋转360°所需的时间。The calculation cycle in the fourth step refers to the time required for the rotation domain to rotate 360°.

所述第四步中的数值收敛的判断方法有两种:(一)以残差值的变化判断;(二)编写程序对数值进行监测。There are two methods for judging the numerical convergence in the fourth step: (1) judging by the change of the residual value; (2) writing a program to monitor the numerical value.

更进一步的方案是:所述第三步中的物性参数设置还包括:设置计算域入口为压力边界条件;设置计算域出口为质量流量边界条件;设置非定常流动计算采用标准k-ε湍流模型;设置时间步长Δt;设置非定常流动计算的初始条件,所述初始条件采用旋喷泵内定常流动的收敛解。A further solution is: the physical parameter setting in the third step also includes: setting the inlet of the calculation domain as a pressure boundary condition; setting the outlet of the calculation domain as a mass flow boundary condition; setting the standard k-ε turbulence model for unsteady flow calculation ; Set the time step Δt; Set the initial conditions for the unsteady flow calculation, the initial conditions adopt the convergent solution of the steady flow in the jet pump.

所述第三步中的时间步长Δt的取值范围为:

Figure BDA00003074961400071
其中,n为旋喷泵的转速值,Z为叶片数,k为>1的整数。The value range of the time step Δt in the third step is:
Figure BDA00003074961400071
Wherein, n is the rotational speed value of the rotary jet pump, Z is the number of blades, and k is an integer >1.

所述第三步中的初始条件采用的定常流动的收敛解是通过转子冻结法计算得出。The convergent solution of the steady flow adopted by the initial conditions in the third step is calculated by the rotor freezing method.

所述第二步中的网格划分软件采用ICEM软件。The grid division software in the second step adopts ICEM software.

所述第三步和第四步中的计算流体动力学软件采用Ansys-Fluent软件。The computational fluid dynamics software in the third step and the fourth step adopts Ansys-Fluent software.

本发明相对于现有技术具备如下的突出优点和效果:Compared with the prior art, the present invention has the following outstanding advantages and effects:

1、本发明方法采取了旋转域与刚性域相结合的计算策略,解决了三维计算域网格重构的技术问题,攻克了现有技术不能计算旋喷泵非定常流场这一技术难点,实现了旋喷泵的非定常流场计算,为旋喷泵的瞬态流动特性分析提供有力工具;1. The method of the present invention adopts the calculation strategy of combining the rotating domain and the rigid domain, solves the technical problem of grid reconstruction in the three-dimensional calculation domain, and overcomes the technical difficulty that the existing technology cannot calculate the unsteady flow field of the jet pump, The calculation of the unsteady flow field of the rotary jet pump is realized, which provides a powerful tool for the analysis of the transient flow characteristics of the rotary jet pump;

2、本发明方法有效运用弹簧光滑法结合局部网格重构法实现网格重建,不用耗费过多的计算时间。2. The method of the present invention effectively uses the spring smoothing method combined with the local mesh reconstruction method to realize mesh reconstruction without consuming too much calculation time.

附图说明Description of drawings

图1是旋喷泵的剖面图;Figure 1 is a sectional view of a rotary jet pump;

图2是本发明方法的流程图;Fig. 2 is a flow chart of the inventive method;

图3(a)是t=0时计算域表面网格示意图;Figure 3(a) is a schematic diagram of the computational domain surface grid at t=0;

图3(b)是t=5Δt时计算域表面网格示意图;Figure 3(b) is a schematic diagram of the computational domain surface grid at t=5Δt;

图3(c)是t=10Δt时计算域表面网格示意图;Figure 3(c) is a schematic diagram of the computational domain surface grid at t=10Δt;

图3(d)是t=15Δt时计算域表面网格示意图;Figure 3(d) is a schematic diagram of the computational domain surface grid at t=15Δt;

图4(a)是t=0时计算域中心截面上集流管入口附近计算域的网格示意图;Fig. 4(a) is a schematic diagram of the computational domain near the inlet of the collector on the central section of the computational domain at t=0;

图4(b)是t=5Δt时计算域中心截面上集流管入口附近计算域的网格示意图;Figure 4(b) is a schematic diagram of the computational domain near the inlet of the collector on the central section of the computational domain at t=5Δt;

图5是利用本发明方法得出的旋喷泵出口流量图;Fig. 5 is the outlet flow figure of the rotary jet pump that utilizes the inventive method to draw;

图6是利用本发明方法得出的无量纲径向力

Figure BDA00003074961400081
图;Fig. 6 is the dimensionless radial force that utilizes the method of the present invention to draw
Figure BDA00003074961400081
picture;

图7是利用本发明方法得出的无量纲径向力

Figure BDA00003074961400082
图;Fig. 7 is the dimensionless radial force that utilizes the method of the present invention to draw
Figure BDA00003074961400082
picture;

其中,1为转子腔、2为叶轮、3为进水段、4为集流管、4.1为集流管出口。Among them, 1 is the rotor cavity, 2 is the impeller, 3 is the water inlet section, 4 is the header, and 4.1 is the outlet of the header.

具体实施方式Detailed ways

下面结合实施例对本发明作进一步详细的描述,但本发明的实施方式不限于此。The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

实施例Example

本发明计算非定常流场的方法,应用于旋喷泵,其流程图见图2,包括如下步骤:The method for calculating the unsteady flow field of the present invention is applied to a rotary jet pump, and its flow chart is shown in Figure 2, including the following steps:

第一步,将旋喷泵中转子腔、叶轮、进水段和集流管定义为流体的计算域,其中,转子腔和叶轮为旋转域,进水段和集流管为刚性域;使用机械制图软件(如Pro/E软件)构造计算域的三维实体,形成三维实体文件;In the first step, the rotor cavity, impeller, water inlet section and header in the jet pump are defined as the calculation domain of the fluid, in which the rotor cavity and impeller are rotating domains, and the water inlet section and header are rigid domains; using Mechanical drawing software (such as Pro/E software) constructs the 3D entity of the calculation domain to form a 3D entity file;

第二步,使用网格划分软件(如ICEM软件)读取三维实体文件,对计算域进行网格划分,得到结构/非结构混合网格初始单元,形成网格文件;The second step is to use meshing software (such as ICEM software) to read the 3D solid file, mesh the computational domain, obtain the initial unit of the structured/unstructured hybrid grid, and form a grid file;

第三步,使用计算流体动力学软件(如Ansys-Fluent)读取网格文件,并进行物性参数设置;The third step is to use computational fluid dynamics software (such as Ansys-Fluent) to read the grid file and set the physical property parameters;

物性参数设置包括设置运动边界,运动边界的设置是指,运动边界的界面设置为流体与转子腔和叶轮所接触的表面,运动规律设置为绕轴转动,运动方式设置为Profile方式;运动边界的设置和控制是动网格计算的重点;对于已知运动规律的运动边界,需要定义运动边界的运动方式,一般可采用Profile(动边界文件)和UDF(用户自定义函数)两种方式来控制;Profile方式适合较为简单的运动规律,如平移和转动;对于比较复杂的动边界运动,则需要采用UDF方式进行控制;虽然本方法的运动边界是流体与转子腔和叶轮所接触的表面,曲面形状比较复杂,但是运动规律却是简单的绕轴转动,因此本方法采用Profile方式定义运动边界的运动方式;The physical property parameter setting includes setting the motion boundary. The setting of the motion boundary means that the interface of the motion boundary is set as the surface where the fluid contacts the rotor cavity and the impeller, the motion law is set to rotate around the axis, and the motion mode is set to Profile mode; Setting and control are the focus of moving mesh calculation; for the moving boundary with known motion rules, it is necessary to define the movement mode of the moving boundary, which can generally be controlled by two methods: Profile (moving boundary file) and UDF (user-defined function) ;The Profile method is suitable for relatively simple motion laws, such as translation and rotation; for more complex dynamic boundary motion, UDF method is required for control; although the motion boundary of this method is the surface in contact with the rotor cavity and impeller, the curved surface The shape is relatively complex, but the law of motion is simple rotation around the axis, so this method uses the Profile method to define the motion mode of the motion boundary;

物性参数设置还包括,设置计算域入口为压力边界条件;设置计算域出口为质量流量边界条件,可根据工况点流量设置质量流量边界条件;设置非定常流动计算采用标准k-ε湍流模型;设置时间步长Δt,Δt不大于相邻的叶轮叶片掠过同一位置的时间差,时间步长Δt根据旋喷泵的转速值n和叶片数Z确定,

Figure BDA00003074961400091
其中,n为旋喷泵的转速值,Z为叶片数,k为>1的整数;设置非定常流动计算的初始条件,初始条件的值采用旋喷泵内定常流动的收敛解,定常流动的收敛解可通过转子冻结法计算得出;The physical property parameter setting also includes setting the inlet of the calculation domain as the pressure boundary condition; setting the outlet of the calculation domain as the mass flow boundary condition, and setting the mass flow boundary condition according to the flow rate of the operating point; setting the standard k-ε turbulence model for unsteady flow calculation; Set the time step Δt, Δt is not greater than the time difference between adjacent impeller blades passing over the same position, the time step Δt is determined according to the speed value n and the number of blades Z of the jet pump,
Figure BDA00003074961400091
Among them, n is the speed value of the rotary jet pump, Z is the number of blades, and k is an integer >1; the initial conditions for unsteady flow calculation are set, and the value of the initial conditions adopts the convergence solution of the steady flow in the rotary jet pump, and the steady flow The converged solution can be calculated by the rotor freezing method;

第四步,使用计算流体动力学软件(如Ansys-Fluent软件),以旋转域旋转360°为一个计算周期,依次对计算周期中各个时间步的数值进行计算,每个时间步的数值计算在计算所得的数值收敛后完成;当一个时间步的数值计算完成后,重建下一时间步的三维实体,通过更新旋转域网格和临近旋转域部分的网格节点,从而重建下一时间步的网格,计算下一时间步的数值,直到完成最后时间步的计算;数值收敛的判断方法有两种:(一)以残差值的变化判断;(二)编写程序对数值进行监测;在不同的时间步中,因运动边界的运动,计算域发生了变形,因此在计算前要获取下一时间步网格,重构下一时间步网格采用两种方案:(1)对网格尺寸和畸变率在容许范围内的区域,先采用弹簧光滑法得到下一时间步的网格节点,然后通过插值运算从现有网格得到下一时间步网格的物理量,从而重构下一时间步的网格;(2)对网格尺寸和畸变率超出容许范围的区域,重新划分网格作为下一时间步网格;下一时间步网格重构后,计算下一时间步的数值,直到完成最后时间步的计算;The fourth step is to use computational fluid dynamics software (such as Ansys-Fluent software), take the rotation domain to rotate 360° as a calculation cycle, and calculate the values of each time step in the calculation cycle in turn. The value of each time step is calculated in The calculated value is completed after the convergence; when the numerical calculation of a time step is completed, the 3D entity of the next time step is reconstructed, and the 3D entity of the next time step is reconstructed by updating the rotation domain grid and the grid nodes adjacent to the rotation domain. Grid, calculate the value of the next time step until the calculation of the last time step is completed; there are two methods for judging numerical convergence: (1) judging by the change of residual value; (2) writing a program to monitor the value; In different time steps, due to the movement of the motion boundary, the calculation domain is deformed, so the grid of the next time step must be obtained before calculation, and two schemes are used to reconstruct the grid of the next time step: (1) the grid In the area where the size and distortion rate are within the allowable range, the spring smoothing method is used to obtain the grid node of the next time step, and then the physical quantity of the next time step grid is obtained from the existing grid through interpolation operation, so as to reconstruct the next time step grid node. The grid of the time step; (2) For the area where the grid size and distortion rate exceed the allowable range, the grid is re-divided as the grid of the next time step; after the grid reconstruction of the next time step, the grid of the next time step is calculated value until the last time step is completed;

采用弹簧光滑法得到下一时间步的网格节点是指,对网格尺寸和畸变率在容许范围内的区域,采取弹簧光滑法,将该区域的网格边简化为具有一定刚度并通过网格节点连接的弹簧,通过改变网格节点位置来拉伸或压缩网格;以边界移动量为弹簧的边界条件,通过求解弹簧系统的力平衡方程得到网格节点的位移增量,最终得到下一时间步的网格节点位置;Using the spring smoothing method to obtain the grid nodes of the next time step means that for the area where the grid size and distortion rate are within the allowable range, the spring smoothing method is used to simplify the grid edges of the area to have a certain stiffness and pass through the mesh. The spring connected to the grid nodes stretches or compresses the grid by changing the position of the grid nodes; taking the boundary movement as the boundary condition of the spring, the displacement increment of the grid nodes is obtained by solving the force balance equation of the spring system, and finally the following Grid node positions at a time step;

当转子腔和叶轮绕轴转过某一角度时,由于固定集流管的存在,旋喷泵旋转域与集流管发生冲突迫使旋转域出现变形;旋转域变形在两个部分,即一部分原来的旋转域变成了集流管,另一部分是转过该角度后集流管留下的空间变成了新旋转域的一部分;因此,新的旋转域是原旋转域减去与新集流管实体重叠的部分,再补上原来的集流管实体留下的部分;任何时刻,旋转域的边界面形状和运动方式都是已知的,旋转域的边界面包括两部分:一部分是与集流管相邻的静止界面,其余部分是与叶轮和转子腔相邻的旋转界面;有了边界的几何形状和运动规律就可以更新得到任意时刻的计算域并重构网格;When the rotor chamber and the impeller rotate around the shaft through a certain angle, due to the existence of the fixed header, the rotating domain of the jet pump conflicts with the collecting pipe, forcing the rotating domain to deform; the rotating domain deforms in two parts, that is, the original part The domain of rotation becomes the header, and the other part is that the space left by the header after turning this angle becomes a part of the new domain of rotation; therefore, the new domain of rotation is the original domain of rotation minus the new collector The overlapping part of the pipe entity is added to the part left by the original header entity; at any time, the shape and movement mode of the boundary surface of the rotation domain are known, and the boundary surface of the rotation domain includes two parts: one part is with The static interface adjacent to the collector, and the rest is the rotating interface adjacent to the impeller and rotor cavity; with the geometry and motion laws of the boundary, the calculation domain at any time can be updated and the mesh can be reconstructed;

在第四步之后还可以包括第五步,计算后处理;计算后处理包括,显示旋喷泵非定常流场计算结果,预测稳态的旋喷泵外特性曲线,得到泵内压力的脉动值(包括脉动频率及脉动幅值)等非定常结果,得到因集流管周围存在压差产生对集流管作用力的大小和方向。After the fourth step, the fifth step can also be included, which is post-calculation processing; the post-calculation processing includes displaying the calculation results of the unsteady flow field of the roto-jet pump, predicting the external characteristic curve of the roto-jet pump in a steady state, and obtaining the pulsation value of the pump internal pressure (including pulsation frequency and pulsation amplitude) and other unsteady results, the magnitude and direction of the force on the header due to the pressure difference around the header can be obtained.

本发明的突出优点是:由于旋喷泵结构的特殊性,目前国内外关于旋喷泵的流场计算只能采用“转子冻结”的定常方法,而关于旋转叶轮机械非定常流场计算的通用办法是采用“滑移网格法”,滑移网格法是让两个刚性域(转子与定子部分)之间做相对运动,但该方法仍不能解决旋喷泵流场的非定常计算;本发明方法采取了旋转域(转子腔、叶轮等旋转部分)与刚性域(进水段、集流管等固定部分)相结合的计算策略,其中,旋转域将随时间发生变形、网格节点位置也发生变化;而临近旋转域部分的网格节点位置可能发生变化,计算域其余部分不随时间发生变形;实现了旋喷泵的非定常流场计算,为旋喷泵的瞬态流动特性分析提供有力工具。同时有效运用弹簧光滑法结合局部网格重构法得到三维计算域新网格节点位置,不用耗费过多的计算时间。The outstanding advantages of the present invention are: due to the particularity of the structure of the rotary jet pump, the current calculation of the flow field of the rotary jet pump at home and abroad can only use the steady method of "rotor freezing", while the general method for the calculation of the unsteady flow field of the rotary impeller machinery The method is to use the "slip grid method", which allows relative motion between two rigid domains (rotor and stator parts), but this method still cannot solve the unsteady calculation of the flow field of the jet pump; The method of the present invention adopts a calculation strategy that combines the rotating domain (rotating parts such as rotor cavity and impeller) with the rigid domain (fixed parts such as water inlet section and header), wherein the rotating domain will deform with time, and the grid nodes The position also changes; while the position of the grid nodes adjacent to the rotating domain may change, the rest of the calculation domain does not deform with time; the calculation of the unsteady flow field of the jet pump is realized, which is the analysis of the transient flow characteristics of the jet pump Provide powerful tools. At the same time, the spring smoothing method combined with the local grid reconstruction method is effectively used to obtain the new grid node positions in the 3D calculation domain without consuming too much calculation time.

本发明旋喷泵的非定常流场计算,掌握旋喷泵流场动静干涉现象,弄清旋喷泵的动态流动特性及其非定常流动机理,对提高旋喷泵的水力性能和工作可靠性、减少振动噪音等不利因素,将具有重要的科学研究价值和工程应用价值。The calculation of the unsteady flow field of the rotary jet pump in the present invention can grasp the dynamic and static interference phenomenon of the flow field of the rotary jet pump, clarify the dynamic flow characteristics of the rotary jet pump and its unsteady flow mechanism, and improve the hydraulic performance and working reliability of the rotary jet pump , reducing vibration and noise and other unfavorable factors will have important scientific research value and engineering application value.

选取一立式小型旋喷泵作为研究对象,旋喷泵设计工况参数为:转速n=2900r/min,流量Q=1.8m3/h,扬程H=100m。工作介质为水,密度ρ=998.2kg/m3,动力粘度μ=1.003×10-3Pa·s,叶轮的叶片数Z=6。应用Pro-E建立旋喷泵的计算域,使用Gambit进行计算域网格的划分,得到网格单元。其中进水段23355单元、旋转域220239单元、集流管159237单元,网格单元总数为402831,网格节点总数为112104。A small vertical jet pump is selected as the research object. The design parameters of the jet pump are: speed n=2900r/min, flow rate Q=1.8m3/h, head H=100m. The working medium is water, density ρ=998.2kg/m3, dynamic viscosity μ=1.003×10-3Pa·s, number of impeller blades Z=6. The calculation domain of the jet pump is established by using Pro-E, and Gambit is used to divide the grid of the calculation domain to obtain the grid units. Among them, there are 23,355 units in the water inlet section, 220,239 units in the rotating domain, and 159,237 units in the header. The total number of grid units is 402,831, and the total number of grid nodes is 112,104.

计算使用Fluent流动软件,由泵转速与叶轮叶片数计算得到叶轮的旋转周期为2.069×10-2s,叶片掠过周期为3.448×10-3s,选取计算时间步长Δt=2.0×10-4s。使用Profile方式定义计算域边界面的转向和转速。为简化计算,变形网格仅限于旋转域。采用弹簧光滑法以及局部网格重构法实现网格变形。图3(a)—(d)分别是t=0、5Δt、10Δt、15Δt时计算域表面网格的示意图。由图3(a)—(d)可见,旋转域除了外表面随固体转动外,与集流管接触的内表面也随时间不断的进行调整,从而实现了计算域的变形和网格重构。图4(a)和图4(b)分别是t=0和t=5Δt时计算域中心截面上集流管入口附近计算域的网格示意图,可对比出集流管入口附近的局部网格随时间的变化。由图4(a)和图4(b)可见,固定集流管内的计算网格保持不变,但旋转域需要随时间不断地调整与集流管相邻的边界,因此旋转域网格出现了不同程度的变形和重构(见箭头所指位置)。Fluent flow software was used for the calculation, and the rotation period of the impeller was calculated from the pump speed and the number of impeller blades to be 2.069×10 -2 s, and the blade sweeping period was 3.448×10 -3 s, and the calculation time step Δt=2.0×10 -3 s was selected . 4 s. Use the Profile method to define the steering and rotation speed of the boundary surface of the computational domain. To simplify calculations, the deformed mesh is limited to the rotation domain. Mesh deformation is realized by spring smoothing method and local mesh reconstruction method. Figure 3(a)-(d) are schematic diagrams of the surface mesh of the computational domain at t=0, 5Δt, 10Δt, and 15Δt, respectively. It can be seen from Figure 3(a)-(d) that in addition to the outer surface of the rotating domain rotating with the solid, the inner surface in contact with the header is also adjusted over time, thus realizing the deformation and mesh reconstruction of the computational domain . Figure 4(a) and Figure 4(b) are schematic diagrams of the grids of the calculation domain near the inlet of the collector on the central section of the calculation domain at t=0 and t=5Δt, respectively, and the local grid near the inlet of the collector can be compared changes over time. It can be seen from Figure 4(a) and Figure 4(b) that the calculation grid in the fixed header remains unchanged, but the rotating domain needs to continuously adjust the boundary adjacent to the header over time, so the rotating domain grid appears different degrees of deformation and reconstruction (see the position indicated by the arrow).

图5给出了计算得到的旋喷泵出口流量随时间的变化曲线,由图5可见,在启动了一段时间(t≈0.010s,约半个旋转周期)后,旋喷泵出口流量值趋于平稳并随时间作规则的周期脉动。在一个旋转周期内,旋喷泵出口流量出现6次脉动,即流量脉动频率与叶轮的叶片数Z相对应。Figure 5 shows the calculated change curve of the outlet flow of the jet pump with time. It can be seen from Figure 5 that after starting for a period of time (t≈0.010s, about half a rotation period), the outlet flow value of the jet pump tends to It is stable and periodically pulsates with time. In one rotation cycle, the outlet flow of the jet pump pulsates 6 times, that is, the flow pulsation frequency corresponds to the number Z of the impeller blades.

图6和图7分别给出了计算得到的无量纲径向力

Figure BDA00003074961400111
Figure BDA00003074961400112
随时间的变化曲线。无量纲径向力的定义为:Figure 6 and Figure 7 respectively show the calculated dimensionless radial force
Figure BDA00003074961400111
and
Figure BDA00003074961400112
Variation curve over time. The dimensionless radial force is defined as:

Ff ii ′′ == Ff ii // 11 22 ρAρA Uu inin 22 ,, ii == xx ,, ythe y

其中A是受力总面积,Fx和Fy分别为x、y方向径向力,Uin为泵入口平均流速。由图6和图7可见,径向力的脉动幅度较大,表明转子腔内液流与集流管的干扰现象不容忽视。当旋喷泵运转正常后,水平方向的径向力

Figure BDA00003074961400114
趋近于负值,纵向的
Figure BDA00003074961400115
趋近于正值,即径向力方向是由轴心指向集流管的背流一侧。Where A is the total force area, F x and F y are the radial forces in the x and y directions, respectively, and U in is the average flow velocity at the pump inlet. It can be seen from Figure 6 and Figure 7 that the pulsation amplitude of the radial force is relatively large, indicating that the interference phenomenon between the liquid flow in the rotor cavity and the collector cannot be ignored. When the rotary jet pump operates normally, the radial force in the horizontal direction
Figure BDA00003074961400114
tends to be negative, the longitudinal
Figure BDA00003074961400115
It tends to a positive value, that is, the radial force direction is from the axis to the back flow side of the collector.

为验证本发明方法的有效性和适用性,将本发明方法所得的性能曲线与实测的性能结果进行对比。采用多功能参数测量仪的微机测试系统,通过微机控制外部设备的启动、停止以及调节,实现数据采集、分析处理等。测量包括在设计转速下的电机三相交流电压、电流、功率、电网频率、转速、旋喷泵进出口压力及流量等参数,最后得到旋喷泵的性能曲线。非稳态压力采用10ms高频动态压力传感器测量。测试所得的性能曲线与本发明方法所得的性能曲线相同。In order to verify the validity and applicability of the method of the present invention, the performance curve obtained by the method of the present invention is compared with the measured performance results. The microcomputer test system adopts multi-function parameter measuring instrument, through which the microcomputer controls the start, stop and adjustment of external equipment, and realizes data collection, analysis and processing, etc. Measurements include motor three-phase AC voltage, current, power, grid frequency, speed, inlet and outlet pressure and flow rate of the rotary jet pump at the design speed, and finally obtain the performance curve of the rotary jet pump. The unsteady pressure is measured by a 10ms high frequency dynamic pressure sensor. The performance curve obtained by the test is the same as the performance curve obtained by the method of the present invention.

上述实施例为本发明较佳的实施方式,但本发明的实施方式并不受上述实施例的限制,其他的任何未背离本发明的精神实质与原理下所作的改变、修饰、替代、组合、简化,均应为等效的置换方式,都包含在本发明的保护范围之内。The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (9)

1. based on the computing method of the rotary-jet pump nonstationary flow field of three-dimensional dynamic mesh, it is characterized in that, comprise the steps:
The first step is defined as computational fields with rotary-jet pump rotor chamber, impeller, inlet segment and header, and wherein, rotor chamber and impeller are defined as the rotation territory in the computational fields, uses the 3D solid of mechanical drawing software construction computational fields, forms the 3D solid file;
Second step, use grid dividing software to read the 3D solid file, computational fields is carried out grid dividing, obtain three-dimensional initial mesh, form grid file;
In the 3rd step, use computational fluid dynamics software to read grid file, and carry out the physical parameter setting; Described physical parameter setting comprises the setting of moving boundaries; The setting of described moving boundaries is meant, the layout setting of the moving boundaries surface that to be fluid contacted with impeller with rotor chamber, and the characteristics of motion is set to sway, and mode of motion is set to the Profile mode;
The 4th step, use computational fluid dynamics software, the numerical value to each time step in the computation period calculates successively; The numerical evaluation of each time step is finished after the numerical value convergence of calculating gained; After the numerical evaluation of a time step is finished, by upgrading rotation territory grid and closing on the grid node of rotation territory part, next time step grid of reconstruct, next time step grid of reconstruct adopts two kinds of schemes: (1) is the zone in permissible range to size of mesh opening and aberration rate, adopt the spring theory of adjustment to obtain the grid node of next time step earlier, obtain the physical quantity of next time step grid by interpolation arithmetic from existing grid then, thus the grid of next time step of reconstruct; (2) size of mesh opening and aberration rate are exceeded the zone of permissible range, repartition grid, as next time step grid; Behind next time step grid reconstruction, calculate the numerical value of next time step, up to finishing the final time calculating in step.
2. the computing method of the rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh according to claim 1, it is characterized in that, the grid node that employing spring theory of adjustment in described the 4th step obtains next time step is meant, the zone in permissible range to size of mesh opening and aberration rate, take the spring theory of adjustment, the grid limit that this is regional is reduced to the spring that has certain rigidity and connect by grid node, stretches or compresses grid by changing the grid node position; With the border amount of movement is the boundary condition of spring, obtains the displacement increment of grid node by the equilibrium equation of finding the solution spring system, finally obtains the grid node position of next time step.
3. the computing method of the rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh according to claim 2 is characterized in that, the computation period in described the 4th step is meant, rotation territory 360 ° of required times of rotation.
4. the computing method of the rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh according to claim 3 is characterized in that, the numerical value convergent determination methods in described the 4th step has two kinds: (one) judges with the variation of residual values; (2) the coding logarithm value is monitored.
5. the computing method of the rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh according to claim 1, the physical parameter setting in described the 3rd step also comprises: the computational fields inlet is set is the pressure boundary condition; The computational fields outlet is set is the mass rate boundary condition; UNSTEADY FLOW is set calculates employing standard k-ε turbulence model; Time step Δ t is set; The starting condition that UNSTEADY FLOW is calculated is set, and described starting condition adopts the moving convergence solution of steady flow in the rotary-jet pump.
6. the computing method of the rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh according to claim 5 is characterized in that, the span of the time step Δ t in described the 3rd step is: Wherein, n is the tachometer value of rotary-jet pump, and Z is the number of blade, and k is>1 integer.
7. the computing method of the rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh according to claim 5 is characterized in that, the permanent mobile convergence solution that the starting condition in described the 3rd step adopts is to calculate by the rotor freezing process.
8. according to the computing method of each described rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh among the claim 1-7, it is characterized in that the grid dividing software in described second step adopts ICEM software.
9. according to the computing method of each described rotary-jet pump nonstationary flow field based on three-dimensional dynamic mesh among the claim 1-7, it is characterized in that the computational fluid dynamics software employing Ansys-Fluent software in described the 3rd step and the 4th step.
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