动态管道系统 [英] Dynamic piping system

问题描述

我尝试使用 Modelica 在 Twinbuilder 中对液压系统进行建模.但是我总是遇到错误，我认为这与收敛问题有关.为了理解问题是什么，我将我的系统简化为动态管道、固定边界和扫描体积，其运动将由正弦函数给出.但是在这种简化的情况下，我仍然遇到错误.即使收到警告，我也能够编译模型.当我尝试求解模型时，.它没有解决.我想问一下你对这个问题有什么建议吗?

这是模型的框图

我在尝试求解模型时遇到的错误如下:

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在 Hochdruckreiniger3_1 上进入初始化模式时发生错误.

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在用户模型的初始化函数中遇到错误.

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初始化模拟器时遇到错误

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残差函数评估在1"的初始点失败来自 Hochdruckreiniger3_1:雅可比评估在1"的初始点失败来自 Hochdruckreiniger3_1:未能在1"中的事件迭代中找到一致的解决方案，0 在 0.0000000000000000E+000来自 Hochdruckreiniger3_1:残差函数评估在3"的初始点失败#r171#"来自 Hochdruckreiniger3_1:初始化失败.

代码如下:

模型 Hochdruckreiniger3//声明真实 V_max = 0.000003;真实 V_tod = 0.000002;实际圆周率 = 3.14；真实 N = 2800；//组件)Modelica.Fluid.Machines.SweptVolume Swept1 (活塞横截面积 = 0.0001131，间隙 = 0.00000250621,重新声明包 Medium = Modelica.Media.Water.StandardWater,nPorts = 1,use_portsData = 真，use_T_start = true,T_start = 293.15);内部 Modelica.Fluid.System 系统；Modelica.Mechanics.Translational.Sources.Position Posit1 (exact = true, useSupport = false);Modelica.Blocks.Sources.Sine Sine1 (振幅 = 0.005567,频率Hz = 46.72，偏移量 = 0.005567，相位 = -pi/2);Modelica.Fluid.Sources.FixedBoundary 边界(p = 4e5，重新声明包Medium = Modelica.Media.Water.StandardWater，nPorts = 1)；Modelica.Fluid.Pipes.DynamicPipe pipe1 (长度 = 0.5,直径 = 0.03,重新声明包 Medium = Modelica.Media.Water.StandardWater,modelStructure = Modelica.Fluid.Types.ModelStructure.av_b);方程//连接连接(Posit1.flange，Swept1.flange)；连接(Sine1.y，Posit1.s_ref)；连接(pipe1.port_b，Swept1.ports[1])；连接(边界.端口[1]，pipe1.port_a)；结束 Hochdruckreiniger3;

解决方案

Dymola 在您的模型中显示两个错误:

1. pi 必须是 constant 或 parameter 以符合 phase 中参数的可变性代码>正弦块.顺便说一下，参考 Modelica.Constants.pi 是一种很好的做法.
2. 在 swept1 中设置 use_portsData = true 但不提供任何端口数据.

解决这两个问题后，模型会模拟但会警告您未明确设置初始值.

I try to model a hydraulic system in Twinbuilder with Modelica. But I get always errors which I think has to do with convergence problem. To understand what the problem is, I simplified my system to a dynamic pipe, fixed boundary, and swept volume whose movement will be given by a sinus function. But I still get an error in this simplified case. I am able to compile the model even though I get warnings. When I try to solve the model,. It is not solved. I want to ask if you give me a suggestion on this problem?

This is block diagramm of the model

Errors which I get when I try to solve the model are as follows:

Error occured when entering initialization mode on Hochdruckreiniger3_1.

Error encountered in the Initialize function of user model.

Error encountered while initializing the simulators

Residual function evaluation failed at initial point for "1" From Hochdruckreiniger3_1: Jacobian evaluation failed at initial point for "1" From Hochdruckreiniger3_1: Failed to find a consistent solution in event iteration in "1", 0 at 0.0000000000000000E+000 From Hochdruckreiniger3_1: Residual function evaluation failed at initial point for "3" "#r171#" From Hochdruckreiniger3_1: Initialization failed.

The code is as follows:

model Hochdruckreiniger3
    //Declaration(s)
    Real V_max = 0.000003;
    Real V_tod = 0.000002;
    Real pi = 3.14;
    Real N = 2800;
    //Component(s)
    Modelica.Fluid.Machines.SweptVolume Swept1 (
        pistonCrossArea = 0.0001131,
        clearance = 0.00000250621,
        redeclare package Medium = Modelica.Media.Water.StandardWater,
        nPorts = 1,
        use_portsData = true,
        use_T_start = true,
        T_start = 293.15);
    inner Modelica.Fluid.System system;
    Modelica.Mechanics.Translational.Sources.Position Posit1 (exact = true, useSupport = false);
    Modelica.Blocks.Sources.Sine Sine1 (
        amplitude = 0.005567,
        freqHz = 46.72,
        offset = 0.005567,
        phase = -pi/2);
    Modelica.Fluid.Sources.FixedBoundary boundary (p = 4e5, redeclare package Medium = Modelica.Media.Water.StandardWater, nPorts = 1);
    Modelica.Fluid.Pipes.DynamicPipe pipe1 (
        length = 0.5,
        diameter = 0.03,
        redeclare package Medium = Modelica.Media.Water.StandardWater,
        modelStructure = Modelica.Fluid.Types.ModelStructure.av_b);


equation

    //Connection(s)
    connect(Posit1.flange, Swept1.flange);
    connect(Sine1.y, Posit1.s_ref);
    connect(pipe1.port_b, Swept1.ports[1]);
    connect(boundary.ports[1], pipe1.port_a);
end  Hochdruckreiniger3;

解决方案

Dymola shows two errors in you model:

1. pi must be a constant or parameter to comply with the variability of the parameter phase in the sine block. By the way, it is good practice to refer to Modelica.Constants.pi.
2. in swept1 you set use_portsData = true but don´t provide any port data.

Fixing these two issues, the model simulates but warns you about initial values not being explicitly set.

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