对齐Amesim氦气PR物性与PNVO流量

app/simulation/core/medium.py

@@ -38,16 +38,29 @@ class GasMedium(Protocol):
 
     def density(self, p: float, T: float) -> float: ...
 
+    def isentropic_density_pressure_factor(
+        self,
+        p: float,
+        T: float,
+        downstream_pressure: float | None = None,
+    ) -> float: ...
+
     def dynamic_viscosity(self, T: float) -> float: ...
 
     def specific_internal_energy(self, T: float) -> float: ...
 
+    def specific_internal_energy_at_pressure(self, p: float, T: float) -> float: ...
+
     def specific_enthalpy(self, T: float) -> float: ...
 
+    def specific_enthalpy_at_pressure(self, p: float, T: float) -> float: ...
+
     def temperature_from_internal_energy(self, u: float) -> float: ...
 
     def temperature_from_enthalpy(self, h: float) -> float: ...
 
+    def temperature_from_pressure_enthalpy(self, p: float, h: float) -> float: ...
+
     def temperature_from_mass_internal_energy(self, m: float, U: float) -> float: ...
 
     def pressure(self, m: float, T: float, V: float) -> float: ...
@@ -96,6 +109,18 @@ class IdealGasMedium:
     def density(self, p: float, T: float) -> float:
         return p / (self.R_gas * T)
 
+    def isentropic_density_pressure_factor(
+        self,
+        p: float,
+        T: float,
+        downstream_pressure: float | None = None,
+    ) -> float:
+        del p
+        del downstream_pressure
+        cp = self.cp_at_temperature(T)
+        cv = self.cv_at_temperature(T)
+        return cv / cp
+
     def dynamic_viscosity(self, T: float) -> float:
         """Return dynamic viscosity using the default air Sutherland law."""
 
@@ -116,6 +141,10 @@ class IdealGasMedium:
             + 0.5 * self.cp_slope * delta_T * delta_T
         )
 
+    def specific_internal_energy_at_pressure(self, p: float, T: float) -> float:
+        del p
+        return self.specific_internal_energy(T)
+
     def specific_enthalpy(self, T: float) -> float:
         delta_T = T - self.T_ref
         return (
@@ -124,6 +153,10 @@ class IdealGasMedium:
             + 0.5 * self.cp_slope * delta_T * delta_T
         )
 
+    def specific_enthalpy_at_pressure(self, p: float, T: float) -> float:
+        del p
+        return self.specific_enthalpy(T)
+
     def temperature_from_internal_energy(self, u: float) -> float:
         reference_internal_energy = self.cv * self.T_ref
         delta_u = u - reference_internal_energy
@@ -156,6 +189,10 @@ class IdealGasMedium:
         delta_T = positive_root if abs(positive_root) <= abs(negative_root) else negative_root
         return self.T_ref + delta_T
 
+    def temperature_from_pressure_enthalpy(self, p: float, h: float) -> float:
+        del p
+        return self.temperature_from_enthalpy(h)
+
     def temperature_from_mass_internal_energy(self, m: float, U: float) -> float:
         if m <= 0.0:
             raise ValueError("Mass must stay positive when recovering temperature.")

app/simulation/core/peng_robinson.py

@@ -6,6 +6,10 @@ from dataclasses import dataclass
 from math import acos, cos, isfinite, log, pi, sqrt
 
 UNIVERSAL_GAS_CONSTANT = 8.31446261815324
+# Simcenter Amesim 2404 ``sag_reinit_eos_`` keeps more digits than the
+# commonly printed Peng-Robinson constants 0.45724 and 0.07780.
+PENG_ROBINSON_A_COEFFICIENT = 0.457235583
+PENG_ROBINSON_B_COEFFICIENT = 0.07779607
 
 
 @dataclass(frozen=True)
@@ -29,7 +33,7 @@ class PengRobinsonFluid:
     @property
     def a_parameter(self) -> float:
         return (
-            0.45724
+            PENG_ROBINSON_A_COEFFICIENT
             * UNIVERSAL_GAS_CONSTANT
             * UNIVERSAL_GAS_CONSTANT
             * self.critical_temperature
@@ -39,7 +43,12 @@ class PengRobinsonFluid:
 
     @property
     def b_parameter(self) -> float:
-        return 0.07780 * UNIVERSAL_GAS_CONSTANT * self.critical_temperature / self.critical_pressure
+        return (
+            PENG_ROBINSON_B_COEFFICIENT
+            * UNIVERSAL_GAS_CONSTANT
+            * self.critical_temperature
+            / self.critical_pressure
+        )
 
     @property
     def kappa(self) -> float:
@@ -62,12 +71,32 @@ class PengRobinsonFluid:
             / (self.critical_temperature * sqrt_reduced_temperature)
         )
 
+    def alpha_temperature_second_derivative(self, temperature: float) -> float:
+        self._validate_temperature(temperature)
+        reduced_temperature = temperature / self.critical_temperature
+        sqrt_reduced_temperature = sqrt(reduced_temperature)
+        alpha_base = 1.0 + self.kappa * (1.0 - sqrt_reduced_temperature)
+        return (
+            self.kappa
+            / (2.0 * self.critical_temperature * self.critical_temperature)
+            * (
+                self.kappa / reduced_temperature
+                + alpha_base / (reduced_temperature * sqrt_reduced_temperature)
+            )
+        )
+
     def attractive_parameter(self, temperature: float) -> float:
         return self.a_parameter * self.alpha(temperature)
 
     def attractive_parameter_temperature_derivative(self, temperature: float) -> float:
         return self.a_parameter * self.alpha_temperature_derivative(temperature)
 
+    def attractive_parameter_temperature_second_derivative(
+        self,
+        temperature: float,
+    ) -> float:
+        return self.a_parameter * self.alpha_temperature_second_derivative(temperature)
+
     def pressure_from_molar_volume(self, temperature: float, molar_volume: float) -> float:
         self._validate_temperature(temperature)
         if molar_volume <= self.b_parameter:
@@ -83,6 +112,51 @@ class PengRobinsonFluid:
             raise ValueError("Density must be positive.")
         return self.pressure_from_molar_volume(temperature, self.molar_mass / density)
 
+    def pressure_temperature_derivative_at_density(
+        self,
+        temperature: float,
+        density: float,
+    ) -> float:
+        self._validate_temperature(temperature)
+        if density <= 0.0:
+            raise ValueError("Density must be positive.")
+        molar_volume = self.molar_mass / density
+        if molar_volume <= self.b_parameter:
+            raise RecoverableTrialStateError(
+                "Molar volume must be larger than Peng-Robinson b parameter."
+            )
+        b = self.b_parameter
+        denominator = molar_volume * (molar_volume + b) + b * (molar_volume - b)
+        return (
+            UNIVERSAL_GAS_CONSTANT / (molar_volume - b)
+            - self.attractive_parameter_temperature_derivative(temperature) / denominator
+        )
+
+    def pressure_density_derivative_at_temperature(
+        self,
+        temperature: float,
+        density: float,
+    ) -> float:
+        self._validate_temperature(temperature)
+        if density <= 0.0:
+            raise ValueError("Density must be positive.")
+        molar_volume = self.molar_mass / density
+        if molar_volume <= self.b_parameter:
+            raise RecoverableTrialStateError(
+                "Molar volume must be larger than Peng-Robinson b parameter."
+            )
+        b = self.b_parameter
+        denominator = molar_volume * (molar_volume + b) + b * (molar_volume - b)
+        pressure_molar_volume_derivative = (
+            -UNIVERSAL_GAS_CONSTANT * temperature / (molar_volume - b) ** 2
+            + self.attractive_parameter(temperature)
+            * 2.0
+            * (molar_volume + b)
+            / denominator**2
+        )
+        molar_volume_density_derivative = -self.molar_mass / (density * density)
+        return pressure_molar_volume_derivative * molar_volume_density_derivative
+
     def reduced_parameters(self, pressure: float, temperature: float) -> tuple[float, float]:
         self._validate_pressure_temperature(pressure, temperature)
         a_alpha = self.attractive_parameter(temperature)
@@ -165,6 +239,63 @@ class PengRobinsonFluid:
         )
         return residual_molar_enthalpy / self.molar_mass
 
+    def residual_specific_internal_energy_at_density(
+        self,
+        temperature: float,
+        density: float,
+    ) -> float:
+        """Return Peng-Robinson internal-energy departure, J/kg."""
+        self._validate_temperature(temperature)
+        if density <= 0.0:
+            raise ValueError("Density must be positive.")
+        molar_volume = self.molar_mass / density
+        b = self.b_parameter
+        if molar_volume <= b:
+            raise RecoverableTrialStateError(
+                "Molar volume must be larger than Peng-Robinson b parameter."
+            )
+        attractive = self.attractive_parameter(temperature)
+        d_attractive_d_temperature = (
+            self.attractive_parameter_temperature_derivative(temperature)
+        )
+        log_argument = (
+            molar_volume + (1.0 + sqrt(2.0)) * b
+        ) / (
+            molar_volume + (1.0 - sqrt(2.0)) * b
+        )
+        residual_molar_internal_energy = (
+            temperature * d_attractive_d_temperature - attractive
+        ) * log(log_argument) / (2.0 * sqrt(2.0) * b)
+        return residual_molar_internal_energy / self.molar_mass
+
+    def residual_isochoric_heat_capacity_at_density(
+        self,
+        temperature: float,
+        density: float,
+    ) -> float:
+        """Return the constant-volume heat-capacity departure, J/kg/K."""
+        self._validate_temperature(temperature)
+        if density <= 0.0:
+            raise ValueError("Density must be positive.")
+        molar_volume = self.molar_mass / density
+        b = self.b_parameter
+        if molar_volume <= b:
+            raise RecoverableTrialStateError(
+                "Molar volume must be larger than Peng-Robinson b parameter."
+            )
+        log_argument = (
+            molar_volume + (1.0 + sqrt(2.0)) * b
+        ) / (
+            molar_volume + (1.0 - sqrt(2.0)) * b
+        )
+        residual_molar_cv = (
+            temperature
+            * self.attractive_parameter_temperature_second_derivative(temperature)
+            * log(log_argument)
+            / (2.0 * sqrt(2.0) * b)
+        )
+        return residual_molar_cv / self.molar_mass
+
     @staticmethod
     def _validate_temperature(temperature: float) -> None:
         if temperature <= 0.0:
@@ -181,7 +312,8 @@ HELIUM_PR = PengRobinsonFluid(
     molar_mass=0.004002602,
     critical_temperature=5.1953,
     critical_pressure=227_460.0,
-    acentric_factor=-0.385,
+    # Simcenter Amesim 2404 helium_eos.data.
+    acentric_factor=-0.382,
 )
 
 NITROGEN_PR = PengRobinsonFluid(