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    Component 146: Gearbox/Bearing
    In This Topic

    Component 146: Gearbox/Bearing


    Specifications

     

    Line connections

    1

    Shaft  inlet

    2

    Shaft outlet


    General       User Input Values       Physics Used       Displays       Example

     

    General

    This component allows to model a gearbox or a bearing. Here both the rotational speeds and the energy losses are considered. It can only be used with the line type “Mechanical shaft“.

    The gearbox is located between the two shafts and serves to change the speed of rotation.

    Here the rotational speed at the outlet can optionally be specified directly as specification value N2 (FSPEC=1), or it can be determined by means of a specified rotational speed ratio N1N2 (FSPEC=2).

    For the bearing, the rotational speed remains constant (FSPEC=3).

    Five variants are available for representing the gear losses and bearing losses respectively:

     

    User Input Values 

    FMODE

    Flag for calculation mode design/off-design

    Like in Parent Profile (Sub Profile option only)

    Expression

    = 0: GLOBAL

    = 1: local off-design (i.e. always off-design mode, even when a design calculation has been done globally)                

    = -1: local design

    FSPEC

    Flag for specification of speeds

    Like in Parent Profile (Sub Profile option only)

    Expression

    =1: Gear ratio N1N2 specified
    =2: Outlet speed N2 specified
    =3: Speed unchanged (bearing)

    N1N2

    Gear ratio
     

    N2

    Output speed           

    FSPECQ

    Specification of power transmission

    Like in Parent Profile (Sub Profile option only)

    Expression

    =1: Use Renk / Tacke formula
    =2: Use power loss characteristic
    =3: Use transmission efficiency characteristic
    =4: Use power loss= MU* shaft power
    =5: Use EQLOSS for calculation of power loss
     

    ETAN

    Transmission efficiency

    QLOSSN

    Transmission loss (nominal)

     

    MU

    Friction coefficient

    EQLOSS

    Power loss function

    Q1N                    

    Drive power (nominal)

    Generally, all inputs that are visible are required. But, often default values are provided.

    For more information on colour of the input fields and their descriptions see Edit Component\Specification values

    For more information on design vs. off-design and nominal values see General\Accept Nominal values


     

    Characteristics Lines

    Characteristic line 1 (CQLOSS):  mechanical power loss QLOSS/Q1N= f (Q1/Q1N)

    Characteristic line 1:  mechanical power loss

         X-Axis         1          Q1/Q1N                    1st point
                            2          Q1/Q1N                    2nd point
                            .
                            N         Q1/Q1N                    last point


         Y-Axis          1         QLOSS/Q1N              1st point
                            2          QLOSS/Q1N              2nd point

                            .
                            N         QLOSS/Q1N              last point
     

    Characteristic line 2 (CETA) transmission efficiency ETA/ETAN= f (Q1/Q1N)

    Characteristic line 2: transmission efficiency

         X-Axis         1         Q1/Q1N                   1st point
                            2          Q1/Q1N                  2nd point
                            .
                            N        Q1/Q1N                   last point


         Y-Axis         1          ETA/ETAN               1st point
                            2          ETA/ETAN               2nd point

                            .
                            N         ETA/ETAN               last point
     

     

     

    Physics Used

    Equations 

    Please note:  EBSILON-internally, the rotational speed of a mechanical shaft is mapped onto the mass flow. Therefore the “mass flows” M1 and M2 appear in the equations.
                           The variables for the pressure (P1 and P2) are not used by the component, but they have to be defined for the equation system. Therefore a pressure equation is   
                           generated as well.

    All load cases

     

             

                    

    if FSPEC=

                    1:            N1N2 * M2 – M1 = 0                                     (1)
                                   N2 = M1/N2N1

                    2:            M2 = N2                                                        (1)
                                   N1N2 = M1/N2

                    3:            M2 – M1 = 0                                                 (1)
                                   N2 = M1
                                   N2N1 = 1

    P2 – P1 = 0                                                                                   (2)    

     

    Design load

     

                                               

    if FSPECQ=

                    1:            if N2<3000
                                                   if N1N2 <= 6
                                                                   ETAG44 = 0.9915-0.00128*(N1N2-1)
                                                   else
                                                                  ETAG44 = 0.9851-0.0027*(N1N2-6)
                                    else
                                                   ETAG44 = 0.989-0.0029*(N1N2-1)


                                   MVGMAX = H1*(1.0D0-ETAG44)

         MVGK = 0.7333* MVGMAX
         DQ = MVGK +(0.2667*MVGMAX/(H1- MVGK))*(H1- MVGK)
         ETA = 1 – DQ/H1
         QLOSS = 0

                    2:            ETA = 1
                                   QLOSS = QLOSSN

                    3:            ETA = ETAN
                                   QLOSS = 0

                    4:            ETA = 1
                                   QLOSS = MU * H1

                    5:            ETA = 1
                                   QLOSS = EQLOSS

    H2 – ETA * H1 = -QLOSS                                                                              (3)

    Part load cases

     

                                               

    if FSPECQ=

                    1:            if N2<3000
                                                   if N1N2 <= 6
                                                                   ETAG44 = 0.9915-0.00128*(N1N2-1)
                                                   else
                                                                   ETAG44 = 0.9851-0.0027*(N1N2-6)
                                    else
                                                   ETAG44 = 0.989-0.0029*(N1N2-1)


                                   MVGMAX = Q1N*(1.0D0-ETAG44)

     

         MVGK = 0.7333* MVGMAX
         DQ = MVGK +(0.2667*MVGMAX/(Q1N- MVGK))*(H1- MVGK)
         ETA = 1 – DQ/H1
         QLOSS = 0

                    2:            ETA = 1
                                   QLOSS = CQLOSS(H1/Q1N) * QLOSSN
                                    (CQLOSS: Mechanical power loss-char line)

                    3:            ETA = CETA(H1/Q1N) * ETAN
                                   QLOSS = 0
                                   (CETA: Transmission efficiency-char line)

                    4:            ETA = 1
                                   QLOSS = MU * H1

                    5:            ETA = 1
                                   QLOSS = EQLOSS

    H2 – ETA * H1 = -QLOSS                                                                              (3)

      


    Component Displays

    Display Option 1

    Display Option 2

    Example

    Click here >> Component 146 Demo << to load an example.