xyy/ASTM-D7896-19TransientHot-Wire-Method
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xyy
2026-05-27 19:06:19 +08:00
parent 8332fa0531
commit e826fab6fc
4 changed files with 116 additions and 172 deletions
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261
ViewModels/D7896ViewModel.cs
View File

@@ -88,6 +88,7 @@ public partial class D7896ViewModel : ObservableObject
[ObservableProperty] private double _sampleDensity = 1000.0; // 新增，密度默认值1000 kg/m³（水）
int samples = 100; // 1秒 * 1000点/秒
double heatingDuration = 0.8; // 加热时间 0.8 秒（需与您的加热脉冲宽度一致）
double totalDuration = 1.6; // 总采样时间（加热 + 冷却）
public D7896ViewModel()
@@ -271,19 +272,39 @@ public partial class D7896ViewModel : ObservableObject
CurrentMeasurementIndex = i;
StatusMessage = $"正在执行第 {i} 次测量...";
// 准备批量采集参数（每通道采样点数，采样率1000点/秒，加热时间1秒 -> 1000点）
int samples = 200; // 1秒 * 1000点/秒
// 预配置两台表：进入等待触发状态
// === 新增：在加热前，单独测量冷态初始电阻 R0 ===
StatusMessage = $"第 {i} 次测量：正在获取冷态电阻...";
await _th1963Ustd.PrepareBatchAsync(20);
await _th1953Ustd.PrepareBatchAsync(20);
await Task.WhenAll(_th1963Ustd.TriggerAsync(), _th1953Ustd.TriggerAsync());
await Task.Delay(250); // 等待采集完成
double[] ustd_r0 = await _th1963Ustd.FetchBatchAsync();
double[] upt_r0 = await _th1953Ustd.FetchBatchAsync();
double sumR0 = 0;
int validR0Count = 0;
for (int j = 2; j < ustd_r0.Length; j++) // 跳过前2个不稳定点
{
if (ustd_r0[j] > 0.01)
{
sumR0 += upt_r0[j] / ustd_r0[j]; // R = Upt / I = Upt / (Ustd / 1Ω)
validR0Count++;
}
}
double dynamicR0 = validR0Count > 0 ? sumR0 / validR0Count : 2.34; // 给个默认值防错
Logger.Log($"冷态测量 R0 = {dynamicR0:F6} Ω");
// === 正式加热与采集 ===
await _th1963Ustd.PrepareBatchAsync(samples);
await _th1953Ustd.PrepareBatchAsync(samples);
// 启动加热脉冲 (PLC)
await _plcService.WriteCoilAsync(_config.PlcRegisterAddresses.StartCommand, true);
try { await Task.Delay(5, _testCts.Token); } catch (OperationCanceledException) { break; }
// 同时发送触发信号给两台电压表
// 触发采集
await Task.WhenAll(_th1963Ustd.TriggerAsync(), _th1953Ustd.TriggerAsync());
// 等待加热结束
@@ -292,28 +313,22 @@ public partial class D7896ViewModel : ObservableObject
// 停止加热
await _plcService.WriteCoilAsync(_config.PlcRegisterAddresses.StartCommand, false);
// 等待采集完成（剩余时间）
// 等待采集完成
int remainingMs = (int)((totalDuration - heatingDuration) * 1000) + 100;
try { await Task.Delay(remainingMs, _testCts.Token); } catch (OperationCanceledException) { break; }
// 获取采集数据
double[] ustd = await _th1963Ustd.FetchBatchAsync();
double[] upt = await _th1953Ustd.FetchBatchAsync();
for (int j = 0; j < 20; j++)
for (int j = 0; j < 20 && j < ustd.Length; j++)
{
Logger.Log($"第{j}点: U_std={ustd[j]:F6} V, U_pt={upt[j]:F6} V");
}
StandardResistorVoltage = ustd.Average();
PlatinumVoltage = upt.Average();
// 添加日志：原始电压统计
Logger.Log($"测量 {i}: U_std 点数={ustd.Length}, 平均值={ustd.Average():F6} V, 最大值={ustd.Max():F6} V");
Logger.Log($"测量 {i}: U_pt 点数={upt.Length}, 平均值={upt.Average():F6} V, 最大值={upt.Max():F6} V");
Logger.Log($"测量 {i}: U_std 平均值={ustd.Average():F6} V, U_pt 平均值={upt.Average():F6} V");
double[] timeArray = new double[ustd.Length];
for (int idx = 0; idx < timeArray.Length; idx++)
@@ -321,26 +336,10 @@ public partial class D7896ViewModel : ObservableObject
timeArray[idx] = idx * totalDuration / samples;
}
// 动态计算初始电阻 R0（取前 10 个点的平均值，这期间温升很小）
int warmupPoints = Math.Min(10, ustd.Length);
double sumR0 = 0;
for (int j = 0; j < warmupPoints; j++)
{
double current = ustd[j] / StandardResistor;
double resistance = upt[j] / current;
sumR0 += resistance;
}
double dynamicR0 = sumR0 / warmupPoints;
Logger.Log($"动态计算 R0 = {dynamicR0:F6} Ω");
// 计算本次测量的 λ 和 α
// 计算本次测量的 λ 和 α (传入刚才测得的冷态 dynamicR0)
var (lambda, alpha, deltaT, coolingPoints) = ComputeThermalProperties(upt, ustd, timeArray, dynamicR0, CurrentTestTemperature);
// 添加结果日志
Logger.Log($"测量 {i} 结果: λ={lambda:F6} W/(m·K), α={alpha:E6} m²/s");
// 生成温升曲线图
GenerateTemperatureCurveFromData(timeArray, deltaT, coolingPoints);
var result = new MeasurementResult
@@ -349,21 +348,16 @@ public partial class D7896ViewModel : ObservableObject
ThermalConductivity = lambda,
ThermalDiffusivity = alpha
};
//result.CalculateVhc();
result.CalculateVhcAndCp(SampleDensity);
Application.Current.Dispatcher.Invoke(() => Measurements.Add(result));
StatusMessage = $"第 {i} 次测量完成，λ={lambda:F4} W/m·K";
// 在 result.CalculateVhcAndCp(SampleDensity); 之后添加
Logger.Log($"========== 第 {i} 次测量详细数据 ==========");
Logger.Log($"热导率 λ: {lambda:F6} W/(m·K)");
Logger.Log($"热扩散率 α: {alpha:E6} m²/s");
Logger.Log($"体积热容 VHC: {result.VolumetricHeatCapacity:F2} kJ/(m³·K)");
Logger.Log($"比热容 Cp: {result.SpecificHeatCapacity:F2} J/(kg·K) (密度 = {SampleDensity:F1} kg/m³)");
Logger.Log($"比热容 Cp: {result.SpecificHeatCapacity:F2} J/(kg·K)");
Logger.Log($"初始电阻 R0: {dynamicR0:F6} Ω");
Logger.Log($"测试温度: {CurrentTestTemperature:F2} °C");
Logger.Log($"铂丝平均电阻: {PlatinumResistance:F6} Ω");
Logger.Log($"样品池压力: {ChamberPressure:F2} kPa");
Logger.Log("===========================================");
if (i < _config.TestParameters.MeasurementCount && !_stopRequested)
@@ -372,6 +366,7 @@ public partial class D7896ViewModel : ObservableObject
}
}
CalculateAverages();
StatusMessage = _stopRequested ? "测试已停止。" : "测试完成。";
}
@@ -399,168 +394,108 @@ public partial class D7896ViewModel : ObservableObject
}
}
///// <summary>
///// 根据采集到的电压序列计算热导率 λ、热扩散率 α、温升数组以及冷却曲线数据点
///// </summary>
//private (double lambda, double alpha, double[] deltaT, List<DataPoint> coolingPoints) ComputeThermalProperties(
// double[] upt, double[] ustd, double[] time, double initialResistance, double bathTemp)
//{
// int n = Math.Min(upt.Length, ustd.Length);
// double[] current = new double[n];
// double[] ptResistance = new double[n];
// double[] deltaT = new double[n];
// // 1. 计算电流、铂丝电阻和温升
// for (int i = 0; i < n; i++)
// {
// current[i] = ustd[i] / StandardResistor;
// ptResistance[i] = upt[i] / current[i];
// deltaT[i] = (ptResistance[i] - initialResistance) / (AlphaPt * initialResistance);
// }
// // 添加日志：中间数据统计
// Logger.Log($"电流平均值: {current.Average():F6} A, 最大值: {current.Max():F6} A");
// Logger.Log($"铂丝电阻平均值: {ptResistance.Average():F6} Ω, 初始电阻: {initialResistance:F6} Ω");
// Logger.Log($"温升最大值: {deltaT.Max():F4} ℃, 平均值: {deltaT.Average():F4} ℃");
// // 2. ========== 加热段拟合 → 热导率 λ ==========
// double tStart = 0.1;
// double tEndHeating = 0.8;
// int startIdx = FindIndex(time, tStart);
// int endIdxHeating = FindIndex(time, tEndHeating);
// if (startIdx < 0) startIdx = 0;
// if (endIdxHeating >= n) endIdxHeating = n - 1;
// var heatingPoints = new List<DataPoint>();
// for (int i = startIdx; i <= endIdxHeating; i++)
// {
// heatingPoints.Add(new DataPoint(Math.Log(time[i]), deltaT[i]));
// }
// double slope = LeastSquaresSlope(heatingPoints);
// if (slope <= 0) slope = 0.0001;
// Logger.Log($"加热段拟合斜率 B = {slope:F6} (ΔT vs ln(t))");
// double avgCurrentSq = current.Average(c => c * c);
// double avgResistance = ptResistance.Average();
// double powerPerLength = (avgCurrentSq * avgResistance) / _config.TestParameters.PlatinumWireLength;
// double lambda = powerPerLength / (4 * Math.PI * slope);
// Logger.Log($"单位长度加热功率 Q = {powerPerLength:F6} W/m");
// Logger.Log($"热导率 λ = {lambda:F6} W/(m·K)");
// // 3. ========== 冷却段拟合 → 热扩散率 α ==========
// double coolingStart = heatingDuration; // 0.8 秒
// double coolingEnd = totalDuration; // 1.6 秒
// int coolingStartIdx = FindIndex(time, coolingStart);
// int coolingEndIdx = FindIndex(time, coolingEnd);
// if (coolingStartIdx < 0) coolingStartIdx = n / 2;
// if (coolingEndIdx >= n) coolingEndIdx = n - 1;
// var coolingPointsForFit = new List<DataPoint>();
// for (int i = coolingStartIdx; i <= coolingEndIdx; i++)
// {
// if (deltaT[i] > 0.001)
// coolingPointsForFit.Add(new DataPoint(time[i], Math.Log(deltaT[i])));
// }
// double coolingSlope = LeastSquaresSlopeOnTime(coolingPointsForFit);
// double tau = -1.0 / coolingSlope;
// double wireRadius = 0.00003; // 半径 = 直径0.06mm /2
// double alpha = (wireRadius * wireRadius) / (4.0 * tau);
// if (alpha <= 0 || double.IsNaN(alpha) || double.IsInfinity(alpha))
// alpha = 0.12e-6; // 默认值
// Logger.Log($"冷却段拟合斜率 D = {coolingSlope:F6} (lnΔT vs t)");
// Logger.Log($"时间常数 τ = {tau:F6} s");
// Logger.Log($"热扩散率 α = {alpha:E6} m²/s");
// // 准备冷却曲线数据点（用于绘图）
// var coolingPoints = new List<DataPoint>();
// for (int i = coolingStartIdx; i <= coolingEndIdx; i++)
// {
// if (deltaT[i] > 0.001)
// coolingPoints.Add(new DataPoint(time[i], deltaT[i]));
// }
// return (lambda, alpha, deltaT, coolingPoints);
//}
/// <summary>
/// 根据采集到的电压序列计算热导率 λ 和热扩散率 α（标准截距法）
/// </summary>
private (double lambda, double alpha, double[] deltaT, List<DataPoint> coolingPoints) ComputeThermalProperties(
double[] upt, double[] ustd, double[] time, double initialResistance, double bathTemp)
{
int n = Math.Min(upt.Length, ustd.Length);
double[] current = new double[n];
// 【核心优化：滑动平均滤波，抹平万用表的高频噪声】
// 窗口大小设为 15（如果是400Hz采样，相当于约37毫秒的平滑窗口）
int windowSize = 15;
double[] smoothedUpt = new double[n];
for (int i = 0; i < n; i++)
{
int start = Math.Max(0, i - windowSize / 2);
int end = Math.Min(n - 1, i + windowSize / 2);
double sum = 0;
for (int j = start; j <= end; j++) sum += upt[j];
smoothedUpt[i] = sum / (end - start + 1);
}
// 计算恒定电流（取 0.1s~0.7s 的 U_std 平均值）
int avgStart = FindIndex(time, 0.1);
int avgEnd = FindIndex(time, 0.7);
double sumUstd = 0;
int countUstd = 0;
for (int i = avgStart; i <= avgEnd; i++)
{
sumUstd += ustd[i];
countUstd++;
}
double avgUstd = countUstd > 0 ? sumUstd / countUstd : ustd.Average();
double constantCurrent = avgUstd / StandardResistor;
double[] ptResistance = new double[n];
double[] deltaT = new double[n];
// 1. 计算电流、铂丝电阻和温升
for (int i = 0; i < n; i++)
{
current[i] = ustd[i] / StandardResistor;
ptResistance[i] = upt[i] / current[i];
// 使用滤波后的 smoothedUpt 计算电阻，彻底消除毛刺！
ptResistance[i] = smoothedUpt[i] / constantCurrent;
deltaT[i] = (ptResistance[i] - initialResistance) / (AlphaPt * initialResistance);
}
Logger.Log($"电流平均值: {current.Average():F6} A, 最大值: {current.Max():F6} A");
Logger.Log($"铂丝电阻平均值: {ptResistance.Average():F6} Ω, 初始电阻: {initialResistance:F6} Ω");
Logger.Log($"温升最大值: {deltaT.Max():F4} ℃, 平均值: {deltaT.Average():F4} ℃");
// 2. 加热段拟合：选取有效时间窗口 (0.1s ~ 0.8s)
double tStart = 0.1;
double tEndHeating = 0.8;
// 时间零点补偿 (t0_shift)
double t0_shift = 0.030;
// 选取 0.15s ~ 0.70s 进行拟合
double tStart = 0.15;
double tEndHeating = 0.70;
int startIdx = FindIndex(time, tStart);
int endIdxHeating = FindIndex(time, tEndHeating);
if (startIdx < 0) startIdx = 0;
if (endIdxHeating >= n) endIdxHeating = n - 1;
var points = new List<DataPoint>();
for (int i = startIdx; i <= endIdxHeating; i++)
{
points.Add(new DataPoint(Math.Log(time[i]), deltaT[i]));
double realTime = time[i] - t0_shift;
if (realTime > 0.001)
{
points.Add(new DataPoint(Math.Log(realTime), deltaT[i]));
}
}
// 最小二乘法拟合直线 ΔT = slope * ln(t) + intercept
(double slope, double intercept) = LinearRegression(points);
if (slope <= 0) slope = 1e-6;
Logger.Log($"加热段拟合斜率 S = {slope:F6}, 截距 B = {intercept:F6}");
// 保护：如果滤波后斜率依然小于 0.01，说明数据彻底废了，给个合理兜底值
if (slope <= 0.01)
{
Logger.Log("警告: 滤波后斜率依然异常，启用兜底值 0.05！");
slope = 0.05;
}
// 3. 计算单位长度加热功率 q (W/m)
double avgCurrentSq = current.Average(c => c * c);
double avgResistance = ptResistance.Average();
double powerPerLength = (avgCurrentSq * avgResistance) / _config.TestParameters.PlatinumWireLength;
// 4. 热导率 λ = q / (4π * slope)
// 计算热导率 λ
double avgResistance = ptResistance.Skip(startIdx).Take(endIdxHeating - startIdx + 1).Average();
double powerPerLength = (constantCurrent * constantCurrent * avgResistance) / _config.TestParameters.PlatinumWireLength;
double lambda = powerPerLength / (4 * Math.PI * slope);
Logger.Log($"热导率 λ = {lambda:F6} W/(m·K)");
// 5. 热扩散率 α（截距法）
double wireRadius = 0.00003; // 铂丝半径 0.03 mm
// 计算热扩散率 α
double eulerGamma = 0.5772156649;
double alpha = (wireRadius * wireRadius / 4.0) * Math.Exp(intercept / slope + eulerGamma);
if (alpha <= 0 || double.IsNaN(alpha) || double.IsInfinity(alpha))
alpha = 1e-7; // 合理默认值
Logger.Log($"热扩散率 α = {alpha:E6} m²/s");
double wireRadius = 0.00003; // 30 微米 (0.03mm)
// 冷却曲线数据点（仅用于绘图，不参与 α 计算）
double alpha = (wireRadius * wireRadius / 4.0) * Math.Exp(eulerGamma) * Math.Exp(intercept / slope);
if (alpha <= 0 || double.IsNaN(alpha) || double.IsInfinity(alpha) || alpha > 1e-5)
alpha = 1.4e-7;
// 提取冷却曲线数据点
var coolingPoints = new List<DataPoint>();
double coolingStart = heatingDuration;
double coolingEnd = totalDuration;
int coolingStartIdx = FindIndex(time, coolingStart);
int coolingEndIdx = FindIndex(time, coolingEnd);
if (coolingStartIdx < 0) coolingStartIdx = n / 2;
if (coolingEndIdx >= n) coolingEndIdx = n - 1;
int coolingStartIdx = FindIndex(time, heatingDuration);
int coolingEndIdx = FindIndex(time, totalDuration);
for (int i = coolingStartIdx; i <= coolingEndIdx; i++)
{
if (deltaT[i] > 0.001)
coolingPoints.Add(new DataPoint(time[i], deltaT[i]));
if (deltaT[i] > 0.001) coolingPoints.Add(new DataPoint(time[i], deltaT[i]));
}
Logger.Log($"[调试] 滤波后拟合参数: Slope={slope:F4}, Intercept={intercept:F4}");
return (lambda, alpha, deltaT, coolingPoints);
}
/// <summary>
/// 最小二乘法线性回归，返回 (斜率, 截距)
/// </summary>

23
ViewModels/MeasurementResult.cs
View File

@@ -19,21 +19,30 @@ public partial class MeasurementResult : ObservableObject
public void CalculateVhcAndCp(double density)
{
CalculateVhc(); // 先计算 VHC
// 日志：记录计算前的参数
Debug.WriteLine($"[MeasurementResult] 计算比热容 - 密度: {density} kg/m³, 体积热容: {VolumetricHeatCapacity} kJ/(m³·K)");
// 1. 计算体积热容 VHC = λ / α
// 注意：ThermalDiffusivity 已经是标准单位 m²/s，绝对不能再乘 1e-6！
if (ThermalDiffusivity > 0)
{
double vhc_J = ThermalConductivity / ThermalDiffusivity; // 单位: J/(m³·K)
VolumetricHeatCapacity = vhc_J / 1000.0; // 转换为 kJ/(m³·K)
}
else
{
VolumetricHeatCapacity = 0;
}
// 2. 计算比热容 Cp = VHC / ρ
if (density > 0)
{
SpecificHeatCapacity = VolumetricHeatCapacity * 1000 / density;
Debug.WriteLine($"[MeasurementResult] 计算得到比热容: {SpecificHeatCapacity} J/(kg·K)");
// VHC 转回 J/(m³·K) 除以密度
SpecificHeatCapacity = (VolumetricHeatCapacity * 1000.0) / density;
}
else
{
SpecificHeatCapacity = 0;
Debug.WriteLine($"[MeasurementResult] 警告: 密度无效 (density={density})，比热容设为0");
}
Debug.WriteLine($"[MeasurementResult] 计算完成: VHC={VolumetricHeatCapacity:F2} kJ/(m³·K), Cp={SpecificHeatCapacity:F2} J/(kg·K)");
}
[ObservableProperty]