Turbine Loss
Loss Type
Ainley Mathieson
- class turbodesign.loss.turbine.ainleymathieson.AinleyMathieson[source]
- __call__(row: BladeRow, upstream: BladeRow) ndarray[tuple[Any, ...], dtype[_ScalarT]][source]
Ainley Mathieson predicts the pressure loss of a turbine nozzle or rotor. Since these correlations are from Cascade experiments, the user should be familar with the reynolds and mach number requirements for each equation and figure. Using something outside the bounds can give inaccuare approximations of loss. Additionally these correlations were done on unoptimized blades so efficiencies maybe lower than what’s attainable. Massflow can also be affected because exit P0 is affected.
This code will attempt use the correct equations and warn the user if mach number is out of range.
Note
alpha: gas flow angle relative to axial direction beta: blade angle relative to axial direction
Traupel
Craig Cox
- class turbodesign.loss.turbine.CraigCox[source]
- __call__(row: BladeRow, upstream: BladeRow) ndarray[tuple[Any, ...], dtype[_ScalarT]][source]
Craig and Cox uses the enthalpy definition of loss to calculate the loss of a turbine stage.
Note
Losses are organized as Group 1 which include profile losses and secondary flows. Group 2 losses include rotor tip leakage, balance losses, guide gland losses, lacing wire losses.
All equation numbers are from the craig cox paper Craig, H. R. M., and H. J. A. Cox. “Performance estimation of axial flow turbines.” Proceedings of the Institution of Mechanical Engineers 185.1 (1970): 407-424.
- Equations:
Eta_t = (Work done - Group 2 losses) / (Work done + Group 1 Losses)
Group1 Losses = (Xp + Xs + Xa)*C1**2/(200gJ) + (Xp + Xs + Xa)*W2**2/(200gJ) Group1 Losses = Stator Component + Rotor Component where C1 and W2 are exit velocities for stator and rotor
i+i_stall = (i+i_stall)_basic + (delta i + stall)_sb + (delta i + stall)_cb
(i+i_stall)_basic from Figure 11 (delta incidence + stall)_sb + (delta incidence + stall)_cb from Figure 12
Profile Loss Xp = x_pb N_pr N_pi N_pt + (delta x_p)_t + (delta x_p)_s/e + (delta x_p)_m
x_pb from Figure 5 but use Figure 4 to calculate Fl. Fl*x*s/b is the x axis for Figure 5
N_pr from figure 3
N_pi from Figure 10
N_pt from Figure 6
(delta x_p)_t
(delta x_p)_s/e from Figure 9
(delta x_p)_m from Figure 8
Kacker Okapuu
- class turbodesign.loss.turbine.kackerokapuu.KackerOkapuu[source]
- __call__(row: BladeRow, upstream: BladeRow) ndarray[tuple[Any, ...], dtype[_ScalarT]][source]
Kacker Okapuu is an updated version of Ainley Mathieson and Dunham Came. This tool uses the pressure loss definition.
Note
All equation numbers are from the Kacker Okapuu paper
- Reference:
Kacker, S. C., and U. Okapuu. “A mean line prediction method for axial flow turbine efficiency.” (1982): 111-119.
Turbine Design (Default)
- class turbodesign.loss.turbine.TD2.TD2[source]
- __call__(row: BladeRow, upstream: BladeRow) ndarray[tuple[Any, ...], dtype[_ScalarT]][source]
TD2-2 manual equations 12a/12b for total pressure loss coefficient.
The implementation mirrors the original TD2 code path, which differs from the textbook definition but preserves legacy behavior. Use primarily for initial estimates.
- Assumptions:
Rotor and stator loss coefficients are equal when design requirements match.
Stage reaction at meanline is 50%.
Axial velocity is constant through the stage.
Stator exit Mach number is 0.8.
- class turbodesign.loss.turbine.TD2.TD2_Reynolds_Correction[source]