OpenWAM
Public Member Functions | List of all members
TurboBearings Class Reference

The TurboBearings class represent the bearing system in a turbocharger. More...

#include <turbo_bearings.hpp>

Public Member Functions

 TurboBearings ()
 
 TurboBearings (stHTMoil *Oil, double L_jb, double R_jb, double h_jb, double k_jb, double k_A_c, double k_A_t, double A_c, double A_t, double k_m, double R_tb_min, double R_tb_max, double k_tb)
 
double h_tb (double T)
 Compute the thrust bearing oil film thickness. More...
 
double P_jb (double T)
 Compute the journal bearing power lossses. More...
 
double P_tb (double T)
 Compute the thrust bearing power losses. More...
 
double get_T_oil_m ()
 Compute the mean temperature of the oil. More...
 
double P_oil (double T1, double n, double p1, double p2, double p3, double p4, double m)
 Compute the power losses in the bearings. More...
 

Detailed Description

The TurboBearings class represent the bearing system in a turbocharger.

The TurboBearing class has methods to compute the power losses in the bearing system.

Definition at line 44 of file turbo_bearings.hpp.

Constructor & Destructor Documentation

◆ TurboBearings() [1/2]

TurboBearings::TurboBearings ( )

Default constructor.

◆ TurboBearings() [2/2]

TurboBearings::TurboBearings ( stHTMoil Oil,
double  L_jb,
double  R_jb,
double  h_jb,
double  k_jb,
double  k_A_c,
double  k_A_t,
double  A_c,
double  A_t,
double  k_m,
double  R_tb_min,
double  R_tb_max,
double  k_tb 
)

Constructor that sets the different parameters.

Initializes the class with its different fixed parameters.

Parameters
OilObject for the oil methods and properties.
L_jbLength of the journal bearing in m.
R_jbRadius of the shaft at the journal bearing in m.
h_jbFilm thickness at the journal bearing in m.
k_jbCorrection factor for the oil tangential speed gradient at the journal bearing.
k_A_cForm factor of the pressure distribution at the compressor wheel.
k_A_tForm factor of the pressure distribution at the turbine wheel.
A_cCompressor disc area in m^2.
A_tTurbine disc area in m^2.
k_mFraction of oil mass flow that goes through the thrust bearing.
R_tb_minMinimum radius of the thrust bearing, in m.
R_tb_maxMaximum radius of the thrust bearing, in m.
k_tbCorrection factor for the oil tangential speed gradient at the thrust bearing.

Member Function Documentation

◆ get_T_oil_m()

double TurboBearings::get_T_oil_m ( )

Compute the mean temperature of the oil.

The mean temperature of the oil is computed assuming that it is equal to the arithmetic mean between the inlet temperature and the outlet temperature, so in adiabatic conditions:

\[ \dot{m} c \left( T_m - T_1 \right) = 0.75 \left( P_{jb} + P_{tb} \right) \]

\[ T_m = T_1 + 0.75 \left(P_{jb} + P_{tb} \right) / \left(\dot{m} c \right) \]

Returns
The mean temperature of the oil, in W.

◆ h_tb()

double TurboBearings::h_tb ( double  T)

Compute the thrust bearing oil film thickness.

A value proportional to the thrust bearing oil film thickness is computed as:

\[ h_{tb} = \left| \frac{k_m \dot{m} 12 g) \mu}{\rho (k_{A_c} A_c (p_2 - p_1) / 4 + k_{A_t} A_t (p_3 - p_4) / 2)}\right| ^{\frac{1}{3}} \]

Parameters
TThe journal bearing oil temperature, in K.
Returns
A value proportional to the oil film thickness.

◆ P_jb()

double TurboBearings::P_jb ( double  T)

Compute the journal bearing power lossses.

The journal bearing power losses are computed as:

\[ P_{jb} = 2 \pi R_{jb}^3 k_jb \frac{L_jb}{h_{jb}} \mu n^2 \]

Parameters
TThe journal bearing oil temperature, in K.
Returns
The journal bearing power losses, in W.

◆ P_oil()

double TurboBearings::P_oil ( double  T1,
double  n,
double  p1,
double  p2,
double  p3,
double  p4,
double  m 
)

Compute the power losses in the bearings.

To compute the power losses first the mean temperature of the oil is computed. Then, the power of both the journal and the thrust bearing are estimated.

Parameters
T1The oil inlet temperature.
nThe turbocharger rotating speed in radians per second.
p1The pressure at the inlet of the compressor in Pa.
p2The pressure at the outlet of the compressor in Pa.
p3The pressure at the inlet of the turbine wheel in Pa.
p4The pressure at the outlet of the turbine in Pa.
mThe oil mass flow rate in kg / s.
Returns
The power losses in the bearing system, in W.

◆ P_tb()

double TurboBearings::P_tb ( double  T)

Compute the thrust bearing power losses.

The thrust bearing power losses are computed as:

\[ P_{tb} = \pi \left( R_{tb,max} ^ 2 - R_{tb,min} ^ 2 \right) \bar{R}_{tb}^2 k_{tb} \mu n^2 / h_{tb} \]

Parameters
TThe thrust bearing oil temperature, in K.
Returns
The thrust bearing power losses, in W.

The documentation for this class was generated from the following file: