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:

FSPECQ=1: application of the empirical formula for gear losses of Renk/Tacke (see equations)
FSPECQ=2: specification of the gear loss QLOSSN in the design case and a characteristic line
CQLOSS for the off-design behaviour of this quantity
FSPECQ=3: specification of the gear efficiency ETAN in the design case and a characteristic
line CETA for the off-design behaviour of this quantity
FSPECQ=4: specification of the friction number MU for bearing losses. The mechanical power
loss as MU*Q1 results from this.
FSPECQ=5: evaluation of the kernel expression EQLOSS for calculating the mechanical power loss

User Input Values

FMODE	Flag for calculation mode design/off-design = 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 =1: Gear ratio N1N2 specified =2: Outlet speed N2 specified =3: Speed unchanged (bearing) =-1: Both speeds specified externally
N1N2	Gear ratio
N2	Output speed
FSPECQ	Specification of power transmission =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 line1
Name: CQLOSS
Title: Mechanical power loss
Description: The power loss QLOSS depends on the supplied power Q1 at port 1. In addition,

The power loss QLOSS depends on the supplied power Q1 at port 1
QLOSS in relation to the drive power at nominal load Q1N

QLOSS/Q1N = f (Q1 / Q1N) or QLOSS= Q1N* f (Q1/Q1N)
X-Axis: Q1/Q1N
Y-Axis: QLOSS/Q1N

Characteristic line2
Name: CETA
Title: Transmission efficiency
Description: The transfer efficiency ETA depends on the supplied power Q1 at port 1. In addition,

The power loss QLOSS depends on the supplied power Q1 at port 1
ETA related to the transmission efficiency at nominal load ETAN

ETA/ETAN = f (Q1/Q1N) or ETA= ETAN * f (Q1/Q1N)
X-Axis: Q1/Q1N
Y-Axis: ETA/ETAN

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 +(0.2667MVGMAX/(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 +(0.2667MVGMAX/(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.

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