using FluidSim.Components; using FluidSim.Core; using FluidSim.Interfaces; using FluidSim.Utils; using SFML.Graphics; using SFML.System; using System; namespace FluidSim.Tests { public class TwoStrokeScenario : Scenario { private Crankshaft crankshaft; private TwoStrokeCylinder cylinder; private PipeSystem pipeSystem; private BoundarySystem boundaries; private Solver solver; private Volume0D intakePlenum; private Port plenumInlet, plenumOutlet; private Volume0D exhaustMuffler; private Port mufflerIn, mufflerOut; private Vehicle vehicle; private int throttleAreaIdx, plenumRunnerIdx, intakeValveIdx, exhaustValveIdx; private float[] orificeAreas; private int intakeOpenIdx, exhaustOpenIdx; private SoundProcessor exhaustSound, intakeSound; private OutdoorExhaustReverb reverb; private double dt; private int stepCount; private float _maxThrottleArea; private float intakePipeArea, exhaustHeaderArea; // -- Override shift from Scenario base class -- public override void ShiftUp() => vehicle.ShiftUp(); public override void ShiftDown() => vehicle.ShiftDown(); public override void Initialize(int sampleRate) { dt = 1.0 / sampleRate; // ---- Vehicle ---- vehicle = new Vehicle(); // ---- Throttle (38 mm) ---- _maxThrottleArea = (float)Units.AreaFromDiameter(38 * Units.mm); // ---- Crankshaft ---- crankshaft = new Crankshaft(2000); crankshaft.CycleLength = 2f * MathF.PI; // two‑stroke crankshaft.Inertia = 0.05f; // engine's own inertia (light) crankshaft.FrictionConstant = 2.5f; crankshaft.FrictionViscous = 0.0015f; // ---- Cylinder (125cc) ---- float bore = 0.054f, stroke = 0.0545f, conRod = 0.109f, compRatio = 12.5f; // Symmetric durations (around BDC) float transferDuration = 130f; // 130° float exhaustDuration = 190f; // 190° cylinder = new TwoStrokeCylinder(bore, stroke, conRod, compRatio, transferDuration, exhaustDuration, crankshaft) { IntakeValveDiameter = 0.038f, IntakeValveLift = 0.010f, ExhaustValveDiameter = 0.040f, ExhaustValveLift = 0.010f }; // ---- Pipe system (60 exhaust cells, simple diffuser) ---- int intakeCells = 8; int runnerCells = 8; int exhaustCells = 60; int totalCells = intakeCells + runnerCells + exhaustCells; int[] pipeStart = { 0, intakeCells, intakeCells + runnerCells }; int[] pipeEnd = { intakeCells, intakeCells + runnerCells, totalCells }; float[] area = new float[totalCells]; float[] dx = new float[totalCells]; float intakeDia = 0.038f; float intakeLenBefore = 0.15f; float intakeLenRunner = 0.20f; intakePipeArea = MathF.PI * 0.25f * intakeDia * intakeDia; // Single‑stage diffuser – 840 mm total, easy to tune float headerDia = 0.042f, headerLen = 0.160f; float diffuserLen = 0.250f, diffuserEndDia = 0.070f; // belly float bellyLen = 0.240f; float convergentLen = 0.120f; float stingerDia = 0.026f, stingerLen = 0.070f; // total = 0.16 + 0.25 + 0.24 + 0.12 + 0.07 = 0.84 m exhaustHeaderArea = MathF.PI * 0.25f * headerDia * headerDia; float bellyArea = MathF.PI * 0.25f * diffuserEndDia * diffuserEndDia; float stingerArea = MathF.PI * 0.25f * stingerDia * stingerDia; float totalExhaustLen = headerLen + diffuserLen + bellyLen + convergentLen + stingerLen; // 840 mm int headerCells = (int)(exhaustCells * (headerLen / totalExhaustLen)); int diffuserCells = (int)(exhaustCells * (diffuserLen / totalExhaustLen)); int bellyCells = (int)(exhaustCells * (bellyLen / totalExhaustLen)); int convergentCells = (int)(exhaustCells * (convergentLen / totalExhaustLen)); int stingerCells = exhaustCells - headerCells - diffuserCells - bellyCells - convergentCells; // Fill cells for (int i = 0; i < intakeCells; i++) { area[i] = intakePipeArea; dx[i] = intakeLenBefore / intakeCells; } for (int i = intakeCells; i < intakeCells + runnerCells; i++) { area[i] = intakePipeArea; dx[i] = intakeLenRunner / runnerCells; } int exhStart = intakeCells + runnerCells; int idx = 0; for (int i = exhStart; i < totalCells; i++) { if (idx < headerCells) { area[i] = exhaustHeaderArea; dx[i] = headerLen / headerCells; } else if (idx < headerCells + diffuserCells) { float t = (idx - headerCells) / (float)(diffuserCells - 1); float dia = headerDia + (diffuserEndDia - headerDia) * t; area[i] = MathF.PI * 0.25f * dia * dia; dx[i] = diffuserLen / diffuserCells; } else if (idx < headerCells + diffuserCells + bellyCells) { area[i] = bellyArea; dx[i] = bellyLen / bellyCells; } else if (idx < headerCells + diffuserCells + bellyCells + convergentCells) { float t = (idx - headerCells - diffuserCells - bellyCells) / (float)(convergentCells - 1); float dia = diffuserEndDia + (stingerDia - diffuserEndDia) * t; area[i] = MathF.PI * 0.25f * dia * dia; dx[i] = convergentLen / convergentCells; } else { area[i] = stingerArea; dx[i] = stingerLen / stingerCells; } idx++; } pipeSystem = new PipeSystem(totalCells, pipeStart, pipeEnd, area, dx, 1.225f, 0f, 101325f); pipeSystem.DampingMultiplier = 1.0f; pipeSystem.EnergyRelaxationRate = 0.5f; pipeSystem.AmbientPressure = 101325f; // ---- Volumes ---- intakePlenum = new Volume0D(0.5e-3f, 101325f, 300f); plenumInlet = intakePlenum.CreatePort(); plenumOutlet = intakePlenum.CreatePort(); exhaustMuffler = new Volume0D(5e-4f, 101325f, 600f); mufflerIn = exhaustMuffler.CreatePort(); mufflerOut = exhaustMuffler.CreatePort(); // ---- Boundary system ---- boundaries = new BoundarySystem(pipeSystem, maxOrifices: 4, maxOpenEnds: 2); throttleAreaIdx = 0; plenumRunnerIdx = 1; intakeValveIdx = 2; exhaustValveIdx = 3; boundaries.AddOpenEnd(pipeIndex: 0, isLeftEnd: true, 101325f, intakePipeArea); intakeOpenIdx = 0; boundaries.AddOpenEnd(pipeIndex: 2, isLeftEnd: false, 101325f, stingerArea); exhaustOpenIdx = 1; boundaries.AddOrifice(plenumInlet, 0, false, throttleAreaIdx, 0.7f); boundaries.AddOrifice(plenumOutlet, 1, true, plenumRunnerIdx, 1.0f); boundaries.AddOrifice(cylinder.IntakePort, 1, false, intakeValveIdx, 0.65f); boundaries.AddOrifice(cylinder.ExhaustPort,2, true, exhaustValveIdx, 0.68f); orificeAreas = new float[4]; orificeAreas[plenumRunnerIdx] = intakePipeArea; // ---- Solver ---- solver = new Solver { SubStepCount = 4, EnableProfiling = false }; // 4 sub‑steps for 60 cells solver.SetTimeStep(dt); solver.SetPipeSystem(pipeSystem); solver.SetBoundarySystem(boundaries); solver.AddComponent(cylinder); solver.AddComponent(intakePlenum); solver.AddComponent(exhaustMuffler); // ---- Sound ---- exhaustSound = new SoundProcessor(sampleRate, 1f) { Gain = 10f }; intakeSound = new SoundProcessor(sampleRate, 1f) { Gain = 10f }; reverb = new OutdoorExhaustReverb(sampleRate); stepCount = 0; Console.WriteLine("125cc Two‑Stroke with vehicle coupling ready."); } public override float Process() { float engineRpm = crankshaft.AngularVelocity * 60f / (2f * MathF.PI); vehicle.ClutchInput = Clutch; var (clutchTorque, effectiveInertia) = vehicle.Update(engineRpm, crankshaft.Inertia, (float)dt); crankshaft.SetEffectiveInertia(effectiveInertia); crankshaft.SetLoadTorque(clutchTorque); // clutch torque now includes drag when locked crankshaft.Step((float)dt); cylinder.PreStep((float)dt); float throttledArea = _maxThrottleArea * Math.Clamp(Throttle, 0.001f, 1f); orificeAreas[throttleAreaIdx] = throttledArea; orificeAreas[intakeValveIdx] = cylinder.IntakeValveArea; orificeAreas[exhaustValveIdx] = cylinder.ExhaustValveArea; boundaries.SetOrificeAreas(orificeAreas); solver.Step(); stepCount++; float exhaustFlow = boundaries.GetOpenEndMassFlow(exhaustOpenIdx); float intakeFlow = boundaries.GetOpenEndMassFlow(intakeOpenIdx); float exhaustDry = exhaustSound.Process(exhaustFlow); float intakeDry = intakeSound.Process(intakeFlow); if (stepCount % 2000 == 0) { float rpm = crankshaft.AngularVelocity * 60f / (2f * MathF.PI); Console.WriteLine($"Step {stepCount}, RPM={rpm:F0}, Gear={vehicle.CurrentGear}, Speed={vehicle.SpeedKmh:F0} km/h"); } return reverb.Process((intakeDry + exhaustDry) * 0.5f); } public override void Draw(RenderWindow target) { float winW = target.GetView().Size.X; float winH = target.GetView().Size.Y; float intakeY = winH / 2f - 40f; float exhaustY = winH / 2f + 80f; float openEndX = 40f; // Intake pipe float x = openEndX; float w = 120f; DrawPipe(target, pipeSystem, 0, intakeY, x, x + w); // Throttle float throttleX = x + w + 5f; var throttleRect = new RectangleShape(new Vector2f(8f, 30f)) { FillColor = Color.Yellow, Position = new Vector2f(throttleX, intakeY - 15f) }; target.Draw(throttleRect); // Plenum float plenW = 40f, plenH = 60f; float plenX = throttleX + 10f; DrawVolume(target, intakePlenum, plenX + plenW / 2f, intakeY - plenH / 2f, plenW, plenH); // Runner float runnerStartX = plenX + plenW + 5f; DrawPipe(target, pipeSystem, 1, intakeY, runnerStartX, runnerStartX + 100f); // Cylinder float cylCX = runnerStartX + 150f; float cylTopY = intakeY - 120f; DrawCylinder(target, cylinder, cylCX, cylTopY, 80f, 240f); // Exhaust pipe float exhStartX = cylCX + 40f + 20f; DrawPipe(target, pipeSystem, 2, exhaustY, exhStartX, winW - 60f, areaScale: 1000f); // Labels float rpm = crankshaft.AngularVelocity * 60f / (2f * MathF.PI); float powerKw = crankshaft.AveragePower * 1e-3f; DrawLabel(target, $"RPM: {rpm:F0}", new Vector2f(20, 90), Color.White, 24); DrawLabel(target, $"Power: {powerKw:F2} kW", new Vector2f(20, 115), Color.White, 24); DrawLabel(target, $"Gear: {vehicle.CurrentGear}", new Vector2f(20, 140), Color.Cyan, 20); DrawLabel(target, $"Speed: {vehicle.SpeedKmh:F0} km/h", new Vector2f(20, 160), Color.Cyan, 20); // Dyno curve float torqueNm = crankshaft.AverageTorque; UpdateDynoCurve(rpm, powerKw, torqueNm); DrawDynoCurve(target, winW - 410f, winH - 260f, 400f, 250f, rpm, powerKw); string gearText = vehicle.CurrentGear == 0 ? "N" : vehicle.CurrentGear.ToString(); DrawLabel(target, $"Gear: {gearText}", new Vector2f(20, 140), Color.Cyan, 20); DrawLabel(target, $"Speed: {vehicle.SpeedKmh:F0} km/h", new Vector2f(20, 160), Color.Cyan, 20); DrawLabel(target, vehicle.Engagement > 0.99f ? "Clutch Locked" : "Clutch Slipping", new Vector2f(20, 180), Color.Cyan, 14); } } }