52 lines
1.7 KiB
C#
52 lines
1.7 KiB
C#
// Components/Crankshaft.cs
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using System;
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namespace FluidSim.Components
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{
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public class Crankshaft
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{
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public double AngularVelocity { get; set; } // rad/s
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public double CrankAngle { get; set; } // rad, 0 … 4π (four‑stroke cycle)
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public double PreviousAngle { get; private set; } // for TDC detection
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public double Inertia { get; set; } = 0.2;
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public double FrictionConstant { get; set; } = 2.0; // N·m
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public double FrictionViscous { get; set; } = 0.005; // N·m per rad/s
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private double externalTorque;
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/// <param name="initialRPM">Idle speed before any combustion torque is applied.</param>
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public Crankshaft(double initialRPM = 400.0)
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{
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AngularVelocity = initialRPM * 2.0 * Math.PI / 60.0;
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CrankAngle = 0.0;
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PreviousAngle = 0.0;
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}
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public void AddTorque(double torque) => externalTorque += torque;
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public void Step(double dt)
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{
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// Save previous angle
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PreviousAngle = CrankAngle;
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// Friction
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double friction = FrictionConstant * Math.Sign(AngularVelocity) + FrictionViscous * AngularVelocity;
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double netTorque = externalTorque - friction;
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double alpha = netTorque / Inertia;
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AngularVelocity += alpha * dt;
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if (AngularVelocity < 0) AngularVelocity = 0; // stall
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CrankAngle += AngularVelocity * dt;
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// Wrap to [0, 4π)
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if (CrankAngle >= 4.0 * Math.PI)
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CrankAngle -= 4.0 * Math.PI;
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else if (CrankAngle < 0)
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CrankAngle += 4.0 * Math.PI;
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externalTorque = 0.0;
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}
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}
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} |