管道直径对模拟速度的影响 - Modelica答案

【问题标题】：Effect of the pipe diameter in speed of the simulation - Modelica管道直径对模拟速度的影响 - Modelica
【发布时间】：2021-01-12 12:58:50
【问题描述】：

我使用 Ansys TwinBuilder R2.4 进行 Modelica 仿真。我在 Modelica 中模拟了一个液压系统，可以在某些条件下进行模拟，例如当位于“Auslass”边界条件之前的管道直径为 5 mm 时，当我将其更改为 8 mm 时，模拟不会进行。它大大减慢了模拟的进度。仅当管道直径发生变化时，模拟速度差异的原因是什么？我添加了框图和模型的代码。

model HD_3Kolben_bsp
    //Declaration(s)
    Real V_max = 0.000003;
    Real V_tod = 0.000002;
    Real N = 2800;
    replaceable package medium = Modelica.Media.Water.StandardWater( );
    Real opening_HP;
    Real opening_LP;
    constant Modelica.SIunits.AbsolutePressure patm = 1e5;
    Real opening_HP_2;
    Real opening_LP_2;
    Real opening_HP_3;
    Real opening_LP_3;
    constant Modelica.SIunits.Frequency freq = 46;
    //Component(s)
    Modelica.Fluid.Machines.SweptVolume Kolben1 (
        pistonCrossArea = 0.0001131,
        clearance = 0.00000250621,
        redeclare package Medium = Modelica.Media.Water.StandardWater,
        nPorts = 1,
        use_portsData = false,
        use_T_start = true,
        T_start = 293.15,
        V(start = 0.005),
        m(start = 0.005));
    inner Modelica.Fluid.System system (p_ambient = 101325);
    Modelica.Mechanics.Translational.Sources.Position Posit1 (exact = true, useSupport = false);
    Modelica.Blocks.Sources.Sine Sine1 (
        amplitude = 0.005567,
        freqHz = freq,
        offset = 0.005567,
        phase = +Modelica.Constants.pi/2.01,
        startTime = 0);
    Modelica.Fluid.Vessels.ClosedVolume ClosedVolume1 (
        V = 0.000005/2,
        nPorts = 3,
        redeclare package Medium = medium,
        use_portsData = false);
    Modelica.Fluid.Pipes.DynamicPipe pipe_Swept_CV_1 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Pipes.DynamicPipe pipe_CV_HD_1 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Sources.FixedBoundary Auslass (p = patm, redeclare package Medium = medium, nPorts = 1);
    Modelica.Fluid.Valves.ValveLinear HDVentile1 (
        dp_nominal = 95,
        m_flow_nominal = 0.05867441,
        redeclare package Medium = medium,
        opening = opening_HP);
    Modelica.Fluid.Pipes.DynamicPipe pipe_ND_CV_1 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Valves.ValveLinear NDVentile1 (
        dp_nominal = 94.35,
        m_flow_nominal = 0.05867441,
        redeclare package Medium = medium,
        opening = opening_LP);
    Modelica.Fluid.Pipes.DynamicPipe pipe_Ein_ND (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Sources.FixedBoundary Einlass (p = 4e5, redeclare package Medium = Modelica.Media.Water.StandardWater, nPorts = 1);
    Modelica.Mechanics.Translational.Sensors.PositionSensor Position;
    Modelica.Mechanics.Translational.Sensors.PositionSensor Position2;
    Modelica.Fluid.Valves.ValveLinear NDVentile2 (
        dp_nominal = 94.35,
        m_flow_nominal = 0.05867441,
        redeclare package Medium = medium,
        opening = opening_LP_2);
    Modelica.Fluid.Pipes.DynamicPipe pipe_ND_CV_2 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Valves.ValveLinear HDVentile2 (
        dp_nominal = 95,
        m_flow_nominal = 0.05867441,
        redeclare package Medium = medium,
        opening = opening_HP_2);
    Modelica.Fluid.Pipes.DynamicPipe pipe_CV_HD_2 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Pipes.DynamicPipe pipe_Swept_CV_2 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Vessels.ClosedVolume ClosedVolume2 (
        V = 0.000005/2,
        nPorts = 3,
        redeclare package Medium = medium,
        use_portsData = false);
    Modelica.Blocks.Sources.Sine Sine2 (
        amplitude = 0.005567,
        freqHz = freq,
        offset = 0.005567,
        phase = +Modelica.Constants.pi/2.01,
        startTime = 7/(3*freq));
    Modelica.Mechanics.Translational.Sources.Position Posit2 (exact = true, useSupport = false);
    Modelica.Fluid.Machines.SweptVolume Kolben2 (
        pistonCrossArea = 0.0001131,
        clearance = 0.00000250621,
        redeclare package Medium = Modelica.Media.Water.StandardWater,
        nPorts = 1,
        use_portsData = false,
        use_T_start = true,
        T_start = 293.15,
        V(start = 0.005),
        m(start = 0.005));
    Modelica.Mechanics.Translational.Sensors.PositionSensor Position3;
    Modelica.Fluid.Valves.ValveLinear NDVentile3 (
        dp_nominal = 94.35,
        m_flow_nominal = 0.05867441,
        redeclare package Medium = medium,
        opening = opening_LP_3);
    Modelica.Fluid.Pipes.DynamicPipe pipe_ND_CV_3 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Valves.ValveLinear HDVentile3 (
        dp_nominal = 95,
        m_flow_nominal = 0.05867441,
        redeclare package Medium = medium,
        opening = opening_HP_3);
    Modelica.Fluid.Pipes.DynamicPipe pipe_CV_HD_3 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Pipes.DynamicPipe pipe_Swept_CV_3 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Vessels.ClosedVolume ClosedVolume3 (
        V = 0.000005/2,
        nPorts = 3,
        redeclare package Medium = medium,
        use_portsData = false);
    Modelica.Blocks.Sources.Sine Sine3 (
        amplitude = 0.005567,
        freqHz = freq,
        offset = 0.005567,
        phase = +Modelica.Constants.pi/2.01,
        startTime = 14/(3*freq));
    Modelica.Mechanics.Translational.Sources.Position Posit3 (exact = true, useSupport = false);
    Modelica.Fluid.Machines.SweptVolume Kolben3 (
        pistonCrossArea = 0.0001131,
        clearance = 0.00000250621,
        redeclare package Medium = Modelica.Media.Water.StandardWater,
        nPorts = 1,
        use_portsData = false,
        use_T_start = true,
        T_start = 293.15,
        V(start = 0.005),
        m(start = 0.005));
    Modelica.Fluid.Sources.FixedBoundary boundary1 (p = 4e5, redeclare package Medium = Modelica.Media.Water.StandardWater, nPorts = 1);
    Modelica.Fluid.Pipes.DynamicPipe pipe1 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Sources.FixedBoundary boundary2 (p = 4e5, redeclare package Medium = Modelica.Media.Water.StandardWater, nPorts = 1);
    Modelica.Fluid.Pipes.DynamicPipe pipe2 (
        length = 0.005,
        diameter = 0.002,
        redeclare package Medium = medium,
        roughness = 2.5E-5);
    Modelica.Fluid.Pipes.DynamicPipe pipe3 (
        length = 0.005,
        diameter = 0.0055,
        redeclare package Medium = medium,
        roughness = 2.5E-5,
        modelStructure = Modelica.Fluid.Types.ModelStructure.av_b);
    Modelica.Fluid.Pipes.DynamicPipe pipe4 (
        length = 0.005,
        diameter = 0.0055,
        redeclare package Medium = medium,
        roughness = 2.5E-5,
        modelStructure = Modelica.Fluid.Types.ModelStructure.av_b);
    Modelica.Fluid.Pipes.DynamicPipe pipe5 (
        length = 0.005,
        diameter = 0.0055,
        redeclare package Medium = medium,
        roughness = 2.5E-5,
        modelStructure = Modelica.Fluid.Types.ModelStructure.av_b);
    Modelica.Fluid.Pipes.DynamicPipe pipe6 (
        length = 5,
        diameter = 0.005,
        redeclare package Medium = medium,
        roughness = 2.5E-5,
        modelStructure = Modelica.Fluid.Types.ModelStructure.a_vb);
    Modelica.Fluid.Vessels.ClosedVolume volume2 (
        V = 3.13e-6,
        nPorts = 4,
        redeclare package Medium = medium,
        use_portsData = false);
    Modelica.Fluid.Fittings.SimpleGenericOrifice orifice (diameter = 0.005, zeta = 5, redeclare package Medium = medium);
    Modelica.Fluid.Pipes.DynamicPipe pipe7 (
        length = 0.005,
        diameter = 0.005,
        redeclare package Medium = medium,
        roughness = 2.5E-5);


equation
    if der(Position.s)>=0 then 
           opening_LP=1;  
           opening_HP=0; 
     else 
           opening_LP=0;
           opening_HP=1;
     end if; 
    if der(Position2.s)>=0 then 
           opening_LP_2=1;  
           opening_HP_2=0; 
     else 
           opening_LP_2=0;
           opening_HP_2=1;
     end if;
     if der(Position3.s)>=0 then 
           opening_LP_3=1;  
           opening_HP_3=0; 
     else 
           opening_LP_3=0;
           opening_HP_3=1;
     end if;
    //Connection(s)
    connect(Posit1.flange, Kolben1.flange);
    connect(Sine1.y, Posit1.s_ref);
    connect(pipe_Swept_CV_1.port_a, Kolben1.ports[1]);
    connect(pipe_CV_HD_1.port_b, HDVentile1.port_a);
    connect(NDVentile1.port_b, pipe_ND_CV_1.port_a);
    connect(Einlass.ports[1], pipe_Ein_ND.port_a);
    connect(Posit1.flange, Position.flange);
    connect(Position2.flange, Posit2.flange);
    connect(NDVentile2.port_b, pipe_ND_CV_2.port_a);
    connect(HDVentile2.port_a, pipe_CV_HD_2.port_b);
    connect(pipe_Swept_CV_2.port_a, Kolben2.ports[1]);
    connect(Sine2.y, Posit2.s_ref);
    connect(Posit2.flange, Kolben2.flange);
    connect(Position3.flange, Posit3.flange);
    connect(NDVentile3.port_b, pipe_ND_CV_3.port_a);
    connect(HDVentile3.port_a, pipe_CV_HD_3.port_b);
    connect(pipe_Swept_CV_3.port_a, Kolben3.ports[1]);
    connect(Sine3.y, Posit3.s_ref);
    connect(Posit3.flange, Kolben3.flange);
    connect(boundary1.ports[1], pipe1.port_a);
    connect(boundary2.ports[1], pipe2.port_a);
    connect(pipe_Ein_ND.port_b, NDVentile1.port_a);
    connect(pipe1.port_b, NDVentile2.port_a);
    connect(pipe2.port_b, NDVentile3.port_a);
    connect(HDVentile1.port_b, pipe3.port_a);
    connect(HDVentile2.port_b, pipe4.port_a);
    connect(HDVentile3.port_b, pipe5.port_a);
    connect(pipe_Swept_CV_1.port_b, ClosedVolume1.ports[1]);
    connect(pipe_ND_CV_1.port_b, ClosedVolume1.ports[2]);
    connect(pipe_CV_HD_1.port_a, ClosedVolume1.ports[3]);
    connect(pipe_Swept_CV_2.port_b, ClosedVolume2.ports[1]);
    connect(pipe_ND_CV_2.port_b, ClosedVolume2.ports[2]);
    connect(pipe_CV_HD_2.port_a, ClosedVolume2.ports[3]);
    connect(pipe_Swept_CV_3.port_b, ClosedVolume3.ports[1]);
    connect(pipe_ND_CV_3.port_b, ClosedVolume3.ports[2]);
    connect(pipe_CV_HD_3.port_a, ClosedVolume3.ports[3]);
    connect(pipe3.port_b, volume2.ports[1]);
    connect(pipe4.port_b, volume2.ports[2]);
    connect(pipe5.port_b, volume2.ports[3]);
    connect(volume2.ports[4], pipe6.port_a);
    connect(orifice.port_a, pipe6.port_b);
    connect(orifice.port_b, pipe7.port_a);
    connect(pipe7.port_b, Auslass.ports[1]);
end  HD_3Kolben_bsp;

最好的问候

【问题讨论】：

您在管道中使用哪种压力损失模型？
我使用 modelStructure "ModelStructure.av_vb" 并且 nNodes 是 2。
管道模型中的压降计算采用哪种模型？它是 Modelica.Fluid 中的默认值吗？
是的，这是默认设置。我没有改变动态管道模型中的压力损失计算模型。

标签： modelica

【解决方案1】：

这可能是很多事情。从屏幕截图中只能给出非常笼统的建议。因为它“只是”一个参数，所以系统的结构不应该改变。因此，它可能与系统的动力学有关。我会先看一下求解器日志，从计算的步数或步长开始。如果这种情况以您所经历的减速的数量级发生变化，那么这是一个很好的起点。

另一个问题可能是喋喋不休，这可以通过对发生的事件数量的了解来判断。这些也应该在求解器日志中可见。

一些有帮助的附加信息：

您使用的是哪种 Modelica 工具？
模型本身（可以生成以下所有内容）
求解器日志（参数更改前后）
翻译日志包括。系统属性，例如方程组的大小（参数更改前后）

恐怕如果没有任何其他信息，您将无法获得完全有用的建议...

【讨论】：

我添加了第一点和第二点的相关信息。我无法生成求解器日志。而且我无法通过超链接添加系统属性。
在 pipe7.diameter = 0.005 的情况下（如果我理解正确，该设置应该可以工作）在 Dymola 2021 中模拟后模拟直接失败。在较新的版本中 - 转换为 MSL 4.0.0 后它抱怨说：IF97 medium function tsat called with too low pressure p = -9384.63 Pa <= 611.657 Pa (triple point pressure) Failed condition: p > 611.657 所以这似乎是媒体工作点的问题。
谢谢，实际上，当 pipe7.diameter =0.005 时，我在大约 180 毫秒时遇到错误。但我没有立即出错。
看起来很奇怪，因为我在任何组件上都没有得到如此奇怪的压力值。
我在TwinBuilder R.2.4中模拟模型时也能看到错误原因吗？如何将错误消息转换为 MSL 4.0.0？

【解决方案2】：

在我看来，您使用默认的 flowModel 来计算压降。该模型取决于管道直径（流态湍流/层流）。

要获得更详细的答案，我需要我的同事在上面的回答中要求的信息。

【讨论】：