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250cc mx engine, and dyno

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max
2026-06-09 20:20:56 +02:00
parent aba9b76530
commit ac2eab6f83
5 changed files with 385 additions and 82 deletions
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156
Scenarios/SingleCylScenario.cs
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@@ -32,53 +32,72 @@ namespace FluidSim.Tests
private double dt;
private int stepCount;
// Use a private field for the maximum throttle area, avoiding any base‑class conflicts
private float _maxThrottleArea;
// pipe area for open end calculations
private float pipeArea;
private float intakePipeArea, exhaustPipeArea;
private const float MaxBrakeTorque = 30.0f; // Nm at full load
public override void Initialize(int sampleRate)
{
dt = 1.0 / sampleRate;
// Maximum throttle area – independent of base class
_maxThrottleArea = (float)Units.AreaFromDiameter(3 * Units.cm); // 1 cm²
// Throttle body diameter 44mm (typical for 250cc MX)
_maxThrottleArea = (float)Units.AreaFromDiameter(44 * Units.mm);
// ---- Crankshaft ----
crankshaft = new Crankshaft(2000);
crankshaft.Inertia = 0.01f;
crankshaft.FrictionConstant = 2f;
crankshaft.FrictionViscous = 0.0f;
crankshaft.Inertia = 0.02f; // kg·m² (crank + flywheel)
crankshaft.FrictionConstant = 3.0f; // Nm – bearings, rings, seals
crankshaft.FrictionViscous = 0.002f; // Nm/(rad/s) – oil windage
// ---- Cylinder (CRF250R) ----
float bore = 0.078f; // 78 mm
float stroke = 0.0522f; // 52.2 mm → 249.4 cc
float conRod = 0.1044f; // 2× stroke
float compRatio = 13.5f; // typical
// Valve events (high‑performance MX cam)
float ivo = 340f, ivc = 600f; // intake opens 20° BTDC (overlap), closes 60° ABDC
float evo = 120f, evc = 380f; // exhaust opens 60° BBDC, closes 20° ATDC
// ---- Cylinder ----
float bore = 0.056f, stroke = 0.057f, conRod = 0.110f, compRatio = 11f;
float ivo = 350f, ivc = 580f, evo = 120f, evc = 370f;
cylinder = new Cylinder(bore, stroke, conRod, compRatio,
ivo, ivc, evo, evc, crankshaft)
{
IntakeValveDiameter = 0.03f,
IntakeValveLift = 0.005f,
ExhaustValveDiameter = 0.028f,
ExhaustValveLift = 0.005f
IntakeValveDiameter = 0.036f, // 36 mm
IntakeValveLift = 0.0095f, // 9.5 mm
ExhaustValveDiameter = 0.030f, // 30 mm
ExhaustValveLift = 0.0085f // 8.5 mm
};
// ---- Pipe system ----
int[] pipeStart = { 0, 10, 20 };
int[] pipeEnd = { 10, 20, 70 };
int totalCells = pipeEnd[^1]; // automatically 70, stays in sync
int totalCells = pipeEnd[^1];
float[] area = new float[totalCells];
float[] dx = new float[totalCells];
float pipeDiameter = 0.02f; // 2 cm
pipeArea = MathF.PI * 0.25f * pipeDiameter * pipeDiameter;
float areaVal = pipeArea;
float intakeLenBefore = 0.2f, intakeLenRunner = 0.2f, exhaustLen = 0.4f;
float[] dx = new float[totalCells];
float intakeDia = 0.040f; // 40 mm intake runner
float exhaustDia = 0.038f; // 38 mm exhaust primary
intakePipeArea = MathF.PI * 0.25f * intakeDia * intakeDia;
exhaustPipeArea = MathF.PI * 0.25f * exhaustDia * exhaustDia;
float intakeLenBefore = 0.15f; // throttle body to plenum
float intakeLenRunner = 0.25f; // plenum to valve
float exhaustLen = 0.50f; // exhaust length
for (int i = 0; i < totalCells; i++)
{
area[i] = areaVal;
if (i < 10) dx[i] = intakeLenBefore / 10f;
else if (i < 20) dx[i] = intakeLenRunner / 10f;
else dx[i] = exhaustLen / 50f;
if (i < 10)
{
area[i] = intakePipeArea; dx[i] = intakeLenBefore / 10f;
}
else if (i < 20)
{
area[i] = intakePipeArea; dx[i] = intakeLenRunner / 10f;
}
else
{
area[i] = exhaustPipeArea; dx[i] = exhaustLen / 50f;
}
}
pipeSystem = new PipeSystem(totalCells, pipeStart, pipeEnd, area, dx,
@@ -88,10 +107,10 @@ namespace FluidSim.Tests
pipeSystem.AmbientPressure = 101325f;
// ---- Volumes ----
intakePlenum = new Volume0D(100e-6f, 101325f, 300f); // 100 mL
intakePlenum = new Volume0D(1.0e-3f, 101325f, 300f); // 1 litre airbox
plenumInlet = intakePlenum.CreatePort();
plenumOutlet = intakePlenum.CreatePort();
exhaustCollector = new Volume0D(10e-6f, 101325f, 800f); // 10 mL (unused but present)
exhaustCollector = new Volume0D(10e-6f, 101325f, 800f); // unused
colIn = exhaustCollector.CreatePort();
colOut = exhaustCollector.CreatePort();
@@ -103,28 +122,20 @@ namespace FluidSim.Tests
intakeValveIdx = 2;
exhaustValveIdx = 3;
// Intake open end (pipe0 left)
boundaries.AddOpenEnd(pipeIndex: 0, isLeftEnd: true, 101325f, pipeArea);
// Open ends (pipe area = pipe cross‑section)
boundaries.AddOpenEnd(pipeIndex: 0, isLeftEnd: true, 101325f, intakePipeArea);
intakeOpenIdx = 0;
// Throttle orifice (plenum inlet to pipe0 right)
boundaries.AddOrifice(plenumInlet, pipeIndex: 0, isLeftEnd: false, throttleAreaIdx, 0.2f);
// Plenum to runner (plenum outlet to pipe1 left)
boundaries.AddOrifice(plenumOutlet, pipeIndex: 1, isLeftEnd: true, plenumRunnerAreaIdx, 1f);
// Intake valve (cylinder intake to pipe1 right)
boundaries.AddOrifice(cylinder.IntakePort, pipeIndex: 1, isLeftEnd: false, intakeValveIdx, 1f);
// Exhaust valve (cylinder exhaust to pipe2 left)
boundaries.AddOrifice(cylinder.ExhaustPort, pipeIndex: 2, isLeftEnd: true, exhaustValveIdx, 1f);
// Exhaust open end (pipe2 right)
boundaries.AddOpenEnd(pipeIndex: 2, isLeftEnd: false, 101325f, pipeArea);
boundaries.AddOpenEnd(pipeIndex: 2, isLeftEnd: false, 101325f, exhaustPipeArea);
exhaustOpenIdx = 1;
// Orifices
boundaries.AddOrifice(plenumInlet, pipeIndex: 0, isLeftEnd: false, throttleAreaIdx, 0.7f); // throttle
boundaries.AddOrifice(plenumOutlet, pipeIndex: 1, isLeftEnd: true, plenumRunnerAreaIdx, 1.0f); // plenum→runner
boundaries.AddOrifice(cylinder.IntakePort, pipeIndex: 1, isLeftEnd: false, intakeValveIdx, 1.0f); // intake valve
boundaries.AddOrifice(cylinder.ExhaustPort, pipeIndex: 2, isLeftEnd: true, exhaustValveIdx, 1.0f); // exhaust valve
orificeAreas = new float[4];
orificeAreas[plenumRunnerAreaIdx] = areaVal; // fixed plenum->runner area
orificeAreas[plenumRunnerAreaIdx] = intakePipeArea; // runner cross‑section (fixed)
// ---- Solver ----
solver = new Solver { SubStepCount = 4, EnableProfiling = false };
@@ -136,22 +147,26 @@ namespace FluidSim.Tests
solver.AddComponent(exhaustCollector);
// ---- Sound ----
exhaustSound = new SoundProcessor(sampleRate, 1f) { Gain = 20f };
intakeSound = new SoundProcessor(sampleRate, 1f) { Gain = 20f };
exhaustSound = new SoundProcessor(sampleRate, 1f) { Gain = 10f };
intakeSound = new SoundProcessor(sampleRate, 1f) { Gain = 10f };
reverb = new OutdoorExhaustReverb(sampleRate);
stepCount = 0;
Console.WriteLine("TestScenario ready.");
Console.WriteLine("CRF250R engine ready.");
}
public override float Process()
{
{
// Manual brake torque (0..30 Nm)
float loadTorque = Load * MaxBrakeTorque;
crankshaft.SetLoadTorque(loadTorque);
crankshaft.Step((float)dt);
cylinder.PreStep((float)dt);
// Update variable orifice areas – use the private _maxThrottleArea
float throttledArea = _maxThrottleArea * Math.Clamp(Throttle, 0.0001f, 1f);
float throttledArea = _maxThrottleArea * Math.Clamp(Throttle, 0.001f, 1f);
orificeAreas[throttleAreaIdx] = throttledArea;
orificeAreas[intakeValveIdx] = cylinder.IntakeValveArea;
orificeAreas[exhaustValveIdx] = cylinder.ExhaustValveArea;
boundaries.SetOrificeAreas(orificeAreas);
@@ -159,41 +174,36 @@ namespace FluidSim.Tests
solver.Step();
stepCount++;
// Retrieve open‑end mass flows for sound synthesis
float exhaustFlow = boundaries.GetOpenEndMassFlow(exhaustOpenIdx);
float intakeFlow = boundaries.GetOpenEndMassFlow(intakeOpenIdx);
float intakeFlow = boundaries.GetOpenEndMassFlow(intakeOpenIdx);
float exhaustDry = exhaustSound.Process(exhaustFlow);
float intakeDry = intakeSound.Process(intakeFlow);
float intakeDry = intakeSound.Process(intakeFlow);
if (stepCount % 1000 == 0)
{
float rpm = crankshaft.AngularVelocity * 60f / (2f * MathF.PI);
float crankDeg = crankshaft.CrankAngle; // degrees (0–720)
Console.WriteLine($"Step {stepCount}, CA={crankDeg:F1} deg, RPM={rpm:F0}, CylP={cylinder.Pressure / 1e5f:F2} bar");
float crankDeg = (crankshaft.CrankAngle + cylinder.PhaseOffset) * 180f / MathF.PI % 720f;
Console.WriteLine($"Step {stepCount}, CA={crankDeg:F1}°, RPM={rpm:F0}, CylP={cylinder.Pressure/1e5f:F2} bar");
Console.WriteLine($" intake flow: {intakeFlow:F6}, exhaust flow: {exhaustFlow:F6}");
// Pipe 0 (intake before throttle)
var (r0L, u0L, p0L) = pipeSystem.GetInteriorStateLeft(0);
var (r0R, u0R, p0R) = pipeSystem.GetInteriorStateRight(0);
Console.WriteLine($" Pipe0 L: rho={r0L:F4} u={u0L:F3} p={p0L/1e5:F3}bar | R: rho={r0R:F4} u={u0R:F3} p={p0R/1e5:F3}bar");
// Pipe 1 (runner)
var (r1L, u1L, p1L) = pipeSystem.GetInteriorStateLeft(1);
var (r1R, u1R, p1R) = pipeSystem.GetInteriorStateRight(1);
Console.WriteLine($" Pipe1 L: rho={r1L:F4} u={u1L:F3} p={p1L/1e5:F3}bar | R: rho={r1R:F4} u={u1R:F3} p={p1R/1e5:F3}bar");
// Pipe 2 (exhaust)
var (r2L, u2L, p2L) = pipeSystem.GetInteriorStateLeft(2);
var (r2R, u2R, p2R) = pipeSystem.GetInteriorStateRight(2);
Console.WriteLine($" Pipe2 L: rho={r2L:F4} u={u2L:F3} p={p2L/1e5:F3}bar | R: rho={r2R:F4} u={u2R:F3} p={p2R/1e5:F3}bar");
// Plenum and cylinder mass
Console.WriteLine($" Plenum P={intakePlenum.Pressure/1e5:F3}bar, mass={intakePlenum.Mass:E4} kg");
Console.WriteLine($" Cyl mass={cylinder.Mass:E4} kg");
}
return reverb.Process(intakeDry + exhaustDry);
return reverb.Process((intakeDry + exhaustDry) * 0.5f);
}
public override void Draw(RenderWindow target)
@@ -205,12 +215,10 @@ namespace FluidSim.Tests
float exhaustY = winH / 2f + 80f;
float openEndX = 40f;
// Intake pipe before throttle (pipe 0)
float pipe1StartX = openEndX;
float pipe1EndX = pipe1StartX + 120f;
DrawPipe(target, pipeSystem, 0, intakeY, pipe1StartX, pipe1EndX);
// Throttle symbol
float throttleX = pipe1EndX + 5f;
var throttleRect = new RectangleShape(new Vector2f(8f, 30f))
{
@@ -219,28 +227,40 @@ namespace FluidSim.Tests
};
target.Draw(throttleRect);
// Plenum
float plenW = 60f, plenH = 80f;
float plenLeftX = throttleX + 10f;
float plenCenterX = plenLeftX + plenW / 2f;
float plenTopY = intakeY - plenH / 2f;
DrawVolume(target, intakePlenum, plenCenterX, plenTopY, plenW, plenH);
// Runner pipe (pipe 1)
float runnerStartX = plenLeftX + plenW + 5f;
float runnerEndX = runnerStartX + 100f;
DrawPipe(target, pipeSystem, 1, intakeY, runnerStartX, runnerEndX);
// Cylinder
float cylCX = runnerEndX + 50f;
float cylTopY = intakeY - 120f;
float cylW = 80f, cylMaxH = 240f;
DrawCylinder(target, cylinder, cylCX, cylTopY, cylW, cylMaxH);
// Exhaust pipe (pipe 2)
float exhStartX = cylCX + cylW / 2f + 20f;
float exhEndX = winW - 60f;
DrawPipe(target, pipeSystem, 2, exhaustY, exhStartX, exhEndX);
// --- RPM & Power 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);
// --- Dyno curve ---
float torqueNm = crankshaft.AverageTorque;
UpdateDynoCurve(rpm, powerKw, torqueNm);
float graphX = winW - 410f;
float graphY = winH - 260f;
float graphW = 400f;
float graphH = 250f;
DrawDynoCurve(target, graphX, graphY, graphW, graphH, rpm, powerKw);
}
}
}