functiondp_tau_centrifugal
Extends from partial_dp_tau (Compute dp and tau_st of a TurboComponent from the current state).
Information
Deprecation notice:
The legacy Reynolds formulation (useLegacyReynolds = true) is deprecated.
When enabled, a warning is issued to inform the user about
the upcoming removal.
The legacy option will be removed in v2.0 of the ThermoFluidStream Library.
Recommended usage:
-
Update your models to
useLegacyReynolds = falseand use it for all new models. - Only enable the legacy option to reproduce results from older simulations.
- Plan to remove any explicit legacy usage before upgrading to v2.0.
Remark:
The legacy Reynolds formulation overestimated friction effects by a factor of 1000. Depending on the operating point, the legacy formulation may lead to deviations of the pump characteristic by a factor of approximately 2–5 compared to the corrected implementation. Simulation results will likely change. Closed loop controllers might have to be adapted.
Documentation:
Centrifugal pump model with head–flow (H–Q) and torque–flow (T–Q) characteristic curves.
H–Q characteristic:
TDH := f_H * (a_h*omega*abs(omega)
- b_h*omega*abs(V_flow)
- c_h*V_flow*abs(V_flow));
T–Q characteristic:
tau_st := (f_Q*f_H/f_eta) *
(v_ref/v_in*a_t*abs(omega)*V_flow
- v_ref/v_in*b_t*abs(V_flow)*V_flow
+ v_i*abs(omega)*omega
+ v_s*abs(omega));
Both characteristic curves are extended to all four quadrants of the
V_flow–omega operating map.
The parameters a, b, c, and v can either be specified directly or derived from three scaling
factors alpha, beta, and gamma, which scale a reference pump.
Reference pump parameters:
omega_D = 314.2 rad/s
V_flow_D = 3.06e-3 m3/s
TDH_D = 3.6610 m
a_h_ref = 4.864e-5 m.s2/rad2
b_h_ref = -2.677 s2/(m2.rad)
c_h_ref = 3.967e+5 s2/m5
a_t_ref = 5.427e-1 N.m.s2/(rad.m3)
b_t_ref = 2.777e+4 N.m.s2/m6
v_i_ref = 1.218e-6 N.m.s2/rad2
v_s_ref = 1.832e-4 N.m.s/rad
f_q_ref = 1
K_D_ref = 9.73e-06 m3/rad
rho_ref_ref = 1.00e3 kg/m3
r_ref = 1.60e-2 m
The characteristic curves are scaled to account for variations in fluid density and viscosity, following the approach described in Gülich, Kreiselpumpen: Handbuch für Entwicklung, Anlageplanung und Betrieb, 3rd edition, Chapter 13.1.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.MassFlowRate | m_flow (from partial_dp_tau) | Mass flow rate | |
| SI.AngularVelocity | omega (from partial_dp_tau) | Angular velocity | |
| Medium.ThermodynamicState | state_in (from partial_dp_tau) | Inlet state | |
| Medium.MassFlowRate | m_flow_norm (from partial_dp_tau) | Normalization mass flow rate | |
| SI.AngularVelocity | omega_norm (from partial_dp_tau) | Normalization angular velocity | |
| SI.Density | rho_min (from partial_dp_tau) | Minimum density (relevant at p=0) | |
| Boolean | useLegacyReynolds | true | = true, if legacy Reynolds formulation is used (overestimates viscosity). Set to false to enable the corrected formulation. Will be removed in ThermoFluidStream v2.0. |
| Boolean | parametrizeByScaling | true | = true, if pump characteristic curve is computed from one design point |
| SI.Height | TDH_D | 3.6610 | Design pressure head (max efficiency) |
| SI.VolumeFlowRate | V_flow_D | 3.06e-3 | Design volume flow (max efficiency) |
| SI.AngularVelocity | omega_D | 314.2 | Design angular velocity |
| Real | K_D_input | 9.73e-06 | Vflow_D / omega_D |
| Integer | f_q_input | 1 | Number of floods |
| SI.Radius | r_input | 1.60e-2 | Pump radius (r2) |
| SI.Density | rho_ref_input | 1.00e3 | Reference density |
| Real | a_h_input | 4.864e-5 | HQ factor 1 |
| Real | b_h_input | -2.677 | HQ factor 2 |
| Real | c_h_input | 3.967e+5 | HQ factor 3 |
| Real | a_t_input | 5.427e-1 | TQ factor 1 |
| Real | b_t_input | 2.777e+4 | TQ factor 2 |
| Real | v_i_input | 1.218e-6 | TQ factor 4 |
| Real | v_s_input | 1.832e-4 | TQ factor 3 |
| Real | Re_mod_min | 1e2 | Minimum modified Reynolds number |
| String | name | getInstanceName() | Hack to access the instance name |
Outputs
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Pressure | dp (from partial_dp_tau) | Pressure difference | |
| SI.Torque | tau_st (from partial_dp_tau) | Steady state torque |
Revisions
-
2026, by Raphael Gebhart (raphael.gebhart@dlr.de):
Fixed mu_in,nu_in (dynamic,kinematic) viscosity bug.