修正动态管与阀门诊断输出

app/simulation/components/amesim/flow/orifices.py

@@ -35,6 +35,7 @@ _FLOWSET_USES_CV = (ParameterCondition("flowset", (2.0,)),)
 _FLOWSET_USES_KV = (ParameterCondition("flowset", (3.0,)),)
 _PN_PRESSURE_RATIO_ACCURACY = 0.9999
 _PN_LAMINAR_SMOOTHING_GAIN = 12.0
+_PNVO001_CLOSED_OPENING_ABS_TOL = 1.0e-12
 _PNOR001_FLOW_COEFFICIENT_GROUP = ParameterGroupDisplaySpec(
     id="flow_coefficient",
     label="流量系数",
@@ -835,6 +836,16 @@ class AmesimPnvo001FixedOpening(AlgebraicComponent):
             downstream_pressure=downstream_pressure,
             upstream_temperature=upstream_temperature,
         )
+        # AMESim reports no vena-contracta velocity while the valve is closed.
+        # Signal propagation around a step can leave a round-off-sized opening,
+        # so apply the same numerical-zero convention to this diagnostic only.
+        if isclose(
+            self.opening,
+            0.0,
+            rel_tol=0.0,
+            abs_tol=_PNVO001_CLOSED_OPENING_ABS_TOL,
+        ):
+            gas_velocity = 0.0
         return {
             "xv": self.opening,
             "cm": mass_flow_parameter,