对齐Amesim氦气PR物性与PNVO流量

app/simulation/components/amesim/media/mediums.py

@@ -4,7 +4,11 @@ from collections.abc import Callable
 from dataclasses import dataclass
 from typing import ClassVar
 
-from app.simulation.core.medium import GasMedium, IdealGasMedium
+from app.simulation.core.medium import (
+    GasMedium,
+    IdealGasMedium,
+    ThermodynamicProperties,
+)
 from app.simulation.core.peng_robinson import HELIUM_PR, PengRobinsonFluid
 
 
@@ -36,18 +40,19 @@ class AmesimHeliumPengRobinsonMedium(IdealGasMedium):
     """AMESim helium with a Peng-Robinson mechanical equation of state.
 
     The pressure-density-temperature relation is evaluated by the shared
-    ``HELIUM_PR`` fluid.  The first public AMESim port keeps the committed
-    constant-heat-capacity caloric model so it can be consumed through the
-    same :class:`GasMedium` contract as ideal-gas air.
+    ``HELIUM_PR`` fluid.  The caloric reference follows the constant NASA
+    polynomial from Simcenter Amesim 2404 ``helium_cp_h_s.data``.
     """
 
     SUBSTANCE_ID: ClassVar[str] = "helium"
     PROPERTY_METHOD_ID: ClassVar[str] = "peng_robinson"
     fluid: ClassVar[PengRobinsonFluid] = HELIUM_PR
+    nasa_cp_over_R: ClassVar[float] = 2.5
+    nasa_enthalpy_constant_K: ClassVar[float] = -745.375
 
     name: str = "AMESimHeliumPengRobinson"
     R_gas: float = HELIUM_PR.specific_gas_constant
-    cp_ref: float = 5193.0
+    cp_ref: float = nasa_cp_over_R * HELIUM_PR.specific_gas_constant
     T_ref: float = 293.15
     cp_slope: float = 0.0
     viscosity_ref: float = 1.96e-5
@@ -56,7 +61,7 @@ class AmesimHeliumPengRobinsonMedium(IdealGasMedium):
 
     @property
     def cv(self) -> float:
-        return 3116.0
+        return (self.nasa_cp_over_R - 1.0) * self.R_gas
 
     def cv_at_temperature(self, T: float) -> float:
         del T
@@ -65,11 +70,201 @@ class AmesimHeliumPengRobinsonMedium(IdealGasMedium):
     def density(self, p: float, T: float) -> float:
         return self.fluid.density(p, T)
 
+    def _real_heat_capacities(
+        self,
+        p: float,
+        T: float,
+    ) -> tuple[float, float, float, float, float]:
+        density = self.density(p, T)
+        pressure_density_derivative = (
+            self.fluid.pressure_density_derivative_at_temperature(
+                T,
+                density,
+            )
+        )
+        pressure_temperature_derivative = (
+            self.fluid.pressure_temperature_derivative_at_density(
+                T,
+                density,
+            )
+        )
+        cv = (
+            self.cv_at_temperature(T)
+            + self.fluid.residual_isochoric_heat_capacity_at_density(T, density)
+        )
+        cp = (
+            cv
+            + T
+            * pressure_temperature_derivative
+            * pressure_temperature_derivative
+            / (density * density * pressure_density_derivative)
+        )
+        if cp <= 0.0 or cv <= 0.0:
+            raise ValueError("Real-gas heat capacities must be positive.")
+        return (
+            cp,
+            cv,
+            density,
+            pressure_density_derivative,
+            pressure_temperature_derivative,
+        )
+
+    def _local_isentropic_density_pressure_factor(
+        self,
+        p: float,
+        T: float,
+    ) -> tuple[float, float]:
+        cp, cv, density, pressure_density_derivative, pressure_temperature_derivative = (
+            self._real_heat_capacities(p, T)
+        )
+        heat_capacity_ratio = cp / cv
+        factor = p / (
+            density * pressure_density_derivative * heat_capacity_ratio
+        )
+        exponent = (
+            p
+            * (heat_capacity_ratio - 1.0)
+            / (
+                heat_capacity_ratio
+                * T
+                * pressure_temperature_derivative
+            )
+        )
+        return factor, exponent
+
+    def isentropic_density_pressure_factor(
+        self,
+        p: float,
+        T: float,
+        downstream_pressure: float | None = None,
+    ) -> float:
+        upstream_factor, isentropic_temperature_exponent = (
+            self._local_isentropic_density_pressure_factor(p, T)
+        )
+        if downstream_pressure is None or downstream_pressure >= p:
+            return upstream_factor
+
+        pressure_ratio = max(downstream_pressure / p, 1.0e-12)
+        isentropic_temperature = max(
+            T * pressure_ratio**isentropic_temperature_exponent,
+            2.2,
+        )
+        downstream_factor, _unused_exponent = (
+            self._local_isentropic_density_pressure_factor(
+                max(downstream_pressure, 1.0),
+                isentropic_temperature,
+            )
+        )
+        # AMESim 2404 saggs_ evaluates the local factor at the upstream
+        # state and at an approximate isentropic downstream state.
+        return 0.5 * (upstream_factor + downstream_factor)
+
     def pressure(self, m: float, T: float, V: float) -> float:
         if V <= 0.0:
             raise ValueError("Volume must stay positive.")
         return self.fluid.pressure_from_density(T, m / V)
 
+    def specific_internal_energy(self, T: float) -> float:
+        return self.R_gas * (
+            (self.nasa_cp_over_R - 1.0) * T
+            + self.nasa_enthalpy_constant_K
+        )
+
+    def specific_internal_energy_at_pressure(self, p: float, T: float) -> float:
+        density = self.density(p, T)
+        return (
+            self.specific_internal_energy(T)
+            + self.fluid.residual_specific_internal_energy_at_density(T, density)
+        )
+
+    def specific_enthalpy(self, T: float) -> float:
+        return self.R_gas * (
+            self.nasa_cp_over_R * T
+            + self.nasa_enthalpy_constant_K
+        )
+
+    def specific_enthalpy_at_pressure(self, p: float, T: float) -> float:
+        return self.specific_enthalpy(T) + self.fluid.residual_specific_enthalpy(p, T)
+
+    def temperature_from_internal_energy(self, u: float) -> float:
+        return (
+            u / self.R_gas - self.nasa_enthalpy_constant_K
+        ) / (self.nasa_cp_over_R - 1.0)
+
+    def temperature_from_enthalpy(self, h: float) -> float:
+        return (
+            h / self.R_gas - self.nasa_enthalpy_constant_K
+        ) / self.nasa_cp_over_R
+
+    def temperature_from_pressure_enthalpy(self, p: float, h: float) -> float:
+        temperature = max(self.temperature_from_enthalpy(h), 2.2)
+        for _iteration in range(16):
+            residual_enthalpy = self.fluid.residual_specific_enthalpy(p, temperature)
+            next_temperature = max(
+                self.temperature_from_enthalpy(h - residual_enthalpy),
+                2.2,
+            )
+            if abs(next_temperature - temperature) <= 1.0e-10 * max(
+                temperature,
+                1.0,
+            ):
+                return next_temperature
+            temperature = next_temperature
+        return temperature
+
+    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.")
+        return self.temperature_from_internal_energy(U / m)
+
+    def properties_from_mU(
+        self,
+        m: float,
+        U: float,
+        V: float,
+    ) -> ThermodynamicProperties:
+        if m <= 0.0:
+            raise ValueError("Mass must stay positive when recovering temperature.")
+        if V <= 0.0:
+            raise ValueError("Volume must stay positive.")
+        density = m / V
+        target_internal_energy = U / m
+        temperature = max(
+            self.temperature_from_internal_energy(target_internal_energy),
+            2.2,
+        )
+        for _iteration in range(16):
+            residual_internal_energy = (
+                self.fluid.residual_specific_internal_energy_at_density(
+                    temperature,
+                    density,
+                )
+            )
+            next_temperature = max(
+                self.temperature_from_internal_energy(
+                    target_internal_energy - residual_internal_energy
+                ),
+                2.2,
+            )
+            if abs(next_temperature - temperature) <= 1.0e-10 * max(
+                temperature,
+                1.0,
+            ):
+                temperature = next_temperature
+                break
+            temperature = next_temperature
+        pressure = self.fluid.pressure_from_density(temperature, density)
+        return ThermodynamicProperties(
+            p=pressure,
+            T=temperature,
+            rho=density,
+            u=target_internal_energy,
+            h=self.specific_enthalpy_at_pressure(
+                pressure,
+                temperature,
+            ),
+        )
+
 
 @dataclass(frozen=True)
 class AmesimGasPropertyModelSpec: