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GAMBIT TURBO FILE FORMAT

© 1998–2007 Fluent, Inc. All rights reserved. D-1

D. GAMBIT TURBO FILE FORMAT

Turbo files are ASCII text files that contain numerical descriptions of turbo-

machinery configurations. Such descriptions typically include the locations

and connectivities of points and curves that describe the hub, casing, tip clear-

ance, and blade profiles of the configuration. GAMBIT allows you to import

either of two types of turbo files:

• Pro/ENGINEER (IBL)

• Native

Pro/ENGINEER (IBL) files are generated by the Pro/ENGINEER CAD pack-

age and are typically assigned the file extension of “.ibl”. Native files are

structured in the native GAMBIT turbo-file format and are typically assigned

the file extension “.tur”. This appendix describes the format of native

GAMBIT turbo files.

� NOTE (1): The GAMBIT turbo file format defines the sequence in which data

records must appear in the file but does not constrain the formatting of data on

any particular record. For example, on a record that contains the Cartesian

coordinates of a single point, the coordinates can appear as strictly formatted

(for example, 3F6.2) or as unformatted, separated by commas or blank

characters.

� NOTE (2): Any data record that begins with a forward slash (/) constitutes a

comment record, and its data is ignored.

Section D.1 describes the general structure of a GAMBIT native turbo file,

including the sequence in which the records must appear in the file. Section

D.2 shows an example turbo file.

General Structure GAMBIT TURBO FILE FORMAT

D-2 © 1998–2007 Fluent, Inc. All rights reserved.

D.1 General Structure

The general structure of a GAMBIT turbo file consists of three sections:

• Header information

• Hub, casing, and tip-clearance data

• Blade data

Header information describes the turbo file version number, the rotational

axis, and the coordinate system type used to specify point locations. Hub,

casing, and tip-clearance data describe the inner and outer boundaries of the

turbo volume (with respect to the axis of revolution). Blade data describes the

shapes of the blades and splitters (optional) that comprise the internal compo-

nents of the turbo volume.

D.1.1 Header Information

The first major section of the turbo file consists of three non-comment data

records that contain header information. Each record appears only once in the

turbo file.

Header information in a GAMBIT turbo file consists of the following items:

• File version number

• Rotational axis

• Coordinate system type

The following subsections describe the items listed above.

GAMBIT TURBO FILE FORMAT General Structure


File Version Number

The file version number documents the format version for the turbo data file.

Each file version number references a unique record sequence and/or format

for the turbo data.

Format

n(1) n(2) n(3)

Data Descriptions

Item Type Description

n(1) Integer Major version number

n(2) Integer Minor version number

n(3) Integer Revision number

Example

/ FILE VERSION NUMBER 1.2.0

1 2 0



Rotational Axis

The rotational axis specifies the coordinate axis about which turbo descriptive

elements, such as the hub and casing edges, are rotated in order to create the

turbo volume.

Format

n

Data Descriptions


n Integer Coordinate axis code, where input values of 0,

1, and 2 represent the x, y, and z coordinate

axes, respectively.

Example

/ ROTATIONAL AXIS: Y-AXIS

1



Coordinate System Type

The coordinate system type specifies the type of the coordinate system point

data used in the turbo data file. The available coordinate system types include:

• Cartesian

• Cylindrical

(NOTE: For the cylindrical coordinate system, angles must be specified in

degrees, not radians.)

Format

n

Data Descriptions


n Integer Coordinate axis code, where input values of 0

and 1 represent the Cartesian and cylindrical

coordinate systems, respectively.

Example

/ COORDINATE SYSTEM TYPE: CARTESIAN

0



D.1.2 Hub, Casing, and Tip-Clearance Data

The second major section of the turbo file consists of data records that

describe the inner and outer boundaries of the turbo volume. The boundaries

are defined in terms of the following curves:

• Hub

• Casing

• Tip-clearance (optional)

The hub and casing data describe sets of connected edges the swept surfaces

of which constitute the inner and outer surfaces of the turbo volume,

respectively. Tip-clearance data describes a set of connected edges that can be

used to define the shapes of the upper surface(s) of the turbo blades and

splitters.

Each data section contains records that specify the following information:

• The number of connected edges in the set

• The number of points for each edge

• Coordinate data for each point

(NOTE: If any edge set—for example, the hub edge set—contains more than

one edge, all endpoints that represent points of connection between edges in

the set must be coincident to within the GAMBIT standard geometry tolerance

(10−6).)

The following subsections describe the items listed above.



Hub Data

Hub data describes the curve the swept surface of which constitutes the inner

boundary surface of the turbo volume.

Format

ne

nt(1)

x(1,1) y(1,1) z(1,1)

x(1,2) y(1,2) z(1,2)

...

x(1,nt(1)) y(1,nt(1)) z(1,nt(1))

nt(2)

x(2,1) y(2,1) z(2,1)

x(2,2) y(2,2) z(2,2)

...

x(2,nt(2)) y(2,nt(2)) z(2,nt(2))

.

.

.

nt(ne)

x(ne,1) y(ne,1) z(ne,1)

x(ne,2) y(ne,2) z(ne,2)

...

x(ne,nt(ne)) y(ne,nt(ne)) z(ne,nt(ne))

Data Descriptions


ne Integer Number of edges used to describe the hub

curve

nt(i) Integer Number of points used to describe edge i.

x(i,j)

y(i,j)

z(i,j)

Real Coordinate locations (x, y, z or r, θ , z) of

point j on edge i.

Example

/ HUB DATA: 1 EDGE DEFINED BY 2 POINTS

1

2

-50.0 0.0 255.0

200.0 0.0 255.0



Casing Data

Casing data describes the curve the swept surface of which constitutes the

outer boundary surface of the turbo volume.

Format

ne

nt(1)

x(1,1) y(1,1) z(1,1)

x(1,2) y(1,2) z(1,2)

...

x(1,nt(1)) y(1,nt(1)) z(1,nt(1))

nt(2)

x(2,1) y(2,1) z(2,1)

x(2,2) y(2,2) z(2,2)

...

x(2,nt(2)) y(2,nt(2)) z(2,nt(2))

.

.

.

nt(ne)

x(ne,1) y(ne,1) z(ne,1)

x(ne,2) y(ne,2) z(ne,2)

...


Data Descriptions


ne Integer Number of edges used to describe the casing

curve

nt(i) Integer Number of points used to describe edge i.

x(i,j)

y(i,j)

z(i,j)


point j on edge i.

Example

/ CASING DATA: 1 EDGE DEFINED BY 2 POINTS

1

2

-50.0 0.0 379.0

200.0 0.0 379.0



Tip-Clearance Data

Tip-clearance data describes a curve that can be used to define the shapes of

the upper surface(s) of the turbo blades and splitters. (NOTE: The turbo data

file must contain at least one record for tip-clearance data. If the turbo con-

figuration does not include a tip-clearance edge set, you must specify the

number of tip-clearances edges (ne) as zero (0).)

Format

ne

nt(1)

x(1,1) y(1,1) z(1,1)

x(1,2) y(1,2) z(1,2)

...

x(1,nt(1)) y(1,nt(1)) z(1,nt(1))

nt(2)

x(2,1) y(2,1) z(2,1)

x(2,2) y(2,2) z(2,2)

...

x(2,nt(2)) y(2,nt(2)) z(2,nt(2))

.

.

.

nt(ne)

x(ne,1) y(ne,1) z(ne,1)

x(ne,2) y(ne,2) z(ne,2)

...


Data Descriptions


ne Integer Number of edges used to describe the tip-

clearance curve

np(i) Integer Number of points used to describe edge i.

x(i,j)

y(i,j)

z(i,j)


point j on edge i.



Example

/ TIP-CLEARANCE DATA: 1 EDGE DEFINED BY 2 POINTS

1

2

-50.0 0.0 360.0

200.0 0.0 300.0



D.1.3 Blade Data

The third major section of the turbo file consists of data records that describe

the blade and (optionally) splitter. Turbo blade data consists of the following

items:

• Number of blades

• Number of profiles and sides

• Profile edge continuity

• Pressure- and suction-side data

The number-of-blades data record specifies whether the turbo configuration

consists of a single blade only or of a blade-and-splitter combination and

appears only once in the set of blade data records. The other data records listed

above are repeated for each blade (or splitter). They include the number of

profiles (that is, sets of edges describing the blade cross section), the profile

edge continuity, as well as the edge data that describes the pressure and

suction sides of each blade.



Number of Blades

The number-of-blades data record specifies whether the turbo configuration

consists of a single blade or a blade-and-splitter combination. This record

appears only once in the turbo data file.

Format

nb

Data Descriptions


nb Integer Number of blades in the turbo configuration:

1 = Blade only

2 = Blade and splitter

Example

/ NUMBER OF BLADES: 1=BLADE ONLY, 2=SPLITTER

1



Number of Profiles and Sides

The number-of-profiles-and-sides data record specifies two items of informa-

tion:

• The number of blade profiles (cross sections) that are included in the

turbo data set

• The number of edges in each profile side

This record appears once for each blade and/or splitter in the turbo data file.

� NOTE (1): You must specify at least two profiles for each blade.

� NOTE (2): The leading and trailing endpoints for each side of a given profile

must be coincident to within the GAMBIT geometry tolerance value (10−6). If

the leading endpoints for the two sides of a given profile are not coincident,

GAMBIT repairs the profile by constructing an edge that links the two leading

endpoints and splitting the edge to create two connected edges at the leading

tip of the profile. Similarly, if the trailing endpoints for the two sides of a

given profile are not coincident, GAMBIT constructs an edge that links the

two trailing endpoints and splits the edge to create two connected edges at the

trailing tip of the profile. (For restrictions on this operation, see NOTE (3),

below.)



� NOTE (3): The coincidence repair operation described in NOTE (2), above, is

restricted by two factors:

• The continuity of edges at the leading and trailing tips of the profile

• A limit on the number of allowable edges on any profile side

With respect to the continuity restriction, GAMBIT repairs configurations that

involve non-coincident leading or trailing profile tips only if the edges are

specified as C(0) continuous at the connecting (that is, leading or trailing)

vertex. (For a description of edge continuity specifications, see “Profile Edge

Continuity,” below.)

With respect to the edge-number limit, GAMBIT allows a maximum of three

edges to be used in the definition of any profile side. As a result, the ability of

GAMBIT to repair non-coincidence at the leading and/or trailing tip(s) of the

profile is limited by the number of edges specified for the profile. The

limitations can be stated as follows.

• If you specify only one edge for each profile side, GAMBIT can

perform the coincidence repair operation on both the leading and

trailing tips of the profile, if necessary.

• If you specify two edges for each profile side, GAMBIT can perform

the coincidence repair operation on either the leading or trailing tip of

the profile.

• If you specify three edges for each profile side, GAMBIT cannot

perform the coincidence repair operation, because the operation would

create at least four edges on each side of the profile.

Format

np(i)

nd(i)



Data Descriptions


np(i) Integer Number of profiles used to describe blade i.

(NOTE: np(i) ≥ 2)

nd(i) Integer Number of edges per side used to describe

each profile for blade i.

(NOTE: nd(i) = 1, 2, or 3.)

Example

/ NUMBER OF PROFILES FOR BLADE 1

2

/ NUMBER OF EDGES PER SIDE FOR EACH PROFILE

2



Profile Edge Continuity

Profile edge continuity defines the continuity between all edges used to

describe blade i. This record appears once for each blade and/or splitter in the

turbo data file.

The allowable edge continuity states—C(0), C(1), and C(2)—are defined as

follows (see Figure D-1).

• C(0)—The edges are connected by a common point (vertex) but the

first and second derivatives of the curves that describe the edges are

not necessarily continuous at the connection point (Figure D-1(a)).

• C(1)—The edges are connected by a common point (vertex), and the

first derivatives of the curves that describe the edges are continuous at

the connection point (Figure D-1(b)). The second derivatives of the

curves that describe the edges are not necessarily continuous at the

connection point.

• C(2)—The edges are connected by a common point (vertex), and both

the first and second derivatives of the curves that describe the edges

are continuous at the connection point (Figure D-1(c)).

(a) C(0) continuity (b) C(1) continuity

(c) C(2) continuity

Connection points

Figure D-1: Edge continuity definitions



� NOTE: Profile edge continuity defines continuity between adjacent edges as

observed at their connecting endpoints. Therefore, to fully specify profile edge

continuity, you must specify continuity at the leading and trailing tips of the

profile and at all intermediate points of connection between the edges used to

define the profile. For example, if a profile includes only one edge per side,

you must specify two continuity values—one for the leading tip of the profile

and one for the trailing tip of the profile. If a profile includes two edges per

side, you must specify three continuity entries—one each for the profile

leading and trailing tips and one for the point of connection between the two

edges that define either side of the profile.

Format

pc(i,1) pc(i,2), ..., pc(i,nd(i+1))

Data Descriptions


pc(i) Integer Profile continuity for all edges used to

describe blade i. (NOTE: Allowable values

include 0, 1, and 2—corresponding to C(0),

C(1), and C(2) continuity, respectively.)

nd(i) Integer Number of edges per side used to describe

each profile for blade i (see “Number of

Profiles and Sides,” above).

Example

/ PROFILE EDGE CONTINUITY

2 2



Pressure- and Suction-Side Data

Pressure- and suction-side data records contain point data that define the

edges used to describe the pressure and suction sides, respectively, of the

blade and splitter. The point data and record sequences must be organized

according to the following rules.

• Point data for each edge must be ordered such that it describes the edge

from its leading endpoint to its trailing endpoint.

• The complete description of each profile consists of all point data that

describes the pressure side of the profile followed by all point data that

describes the suction side of the profile.

• The data records must be ordered such that descriptions of the profiles

appear in spanwise order, from the hub to the casing (see the example

turbo data file described in Section D.2, below).

Format

nt(k,1)

x(k,1,1) y(k,1,1) z(k,1,1)

x(k,1,2) y(k,1,2) z(k,1,2)

...

x(k,1,nt(k,1)) y(k,1,nt(k,1)) z(k,1,nt(k,1))

Data Descriptions


nt(k,i) Integer Number of points used to describe pressure-

side edge i of profile k.

x(k,i,j)

y(k,i,j)

z(k,i,j)


point j on edge i for profile k.



Example

/ PRESSURE-SIDE DATA FOR PROFILE 1 (2 EDGES PER SIDE)

/ EDGE 1

/ NUMBER OF POINTS FOR EDGE 1

4

/ POINT DATA FOR PROFILE 1, PRESSURE SIDE, EDGE 1

0.00 0.00 250.00

9.00 8.64 250.00

21.00 12.72 250.00

33.00 18.96 250.00


5

/ POINT DATA FOR PROFILE 1, PRESSURE SIDE, EDGE 2

33.00 18.96 250.00

45.00 27.84 250.00

60.00 44.04 250.00

72.00 61.44 250.00

86.88 78.96 250.00

/

/ SUCTION-SIDE DATA FOR PROFILE 1 (2 EDGES PER SIDE)

/ EDGE 1


4

/ POINT DATA FOR PROFILE 1, SUCTION SIDE, EDGE 1

0.00 0.00 250.00

9.00 -9.36 250.00

21.00 -11.70 250.00

33.00 -9.84 250.00


5

/ POINT DATA FOR PROFILE 1, SUCTION SIDE, EDGE 2

33.00 -9.84 250.00

45.00 -2.88 250.00

60.00 15.24 250.00

72.00 36.24 250.00

86.88 78.96 250.00

Example GAMBIT Turbo File GAMBIT TURBO FILE FORMAT


D.2 Example GAMBIT Turbo File

The following example file demonstrates the native GAMBIT turbo file format

described above. The file describes a turbo configuration in which the hub and

casing edges are described by two and one edge(s), respectively, and for which

a tip-clearance edge is defined. The configuration includes a turbo blade and

splitter, each of which is defined by two profiles, and each profile includes

two edges on each side.

TURBO EXAMPLE FILE

/

/ FILE VERSION

1 3 1

/

/ ROTATIONAL AXIS

2

/

/ COORDINATE SYSTEM TYPE: CARTESIAN

0

/

/ HUB EDGE DATA

2

2

0 4 -5

0 4 0

3

0 4 0

0.2 4 2.5

0 4 5

/

/ CASING EDGE DATA

1

2

0 10 -5

0 10 5

/

/ TIP-CLEARANCE EDGE DATA

1

2

0 9 -5

0 9 5

/

/ BLADE DATA: 2 BLADES, 2 PROFILES/BLADE, 2 EDGES/SIDE

2

/

/ BLADE 1

2

2


2 1 0

GAMBIT TURBO FILE FORMAT Example GAMBIT Turbo File


/ BLADE 1, PROFILE 1, PRESSURE SIDE

3

0.0 3.8 -3

0.2 3.8 -2

0.5 3.8 0

2

0.5 3.8 0

0.1 3.8 3

/ BLADE 1, PROFILE 1, SUCTION SIDE

3

0.0 3.8 -3

-0.2 3.8 -2

-0.5 3.8 0

2

-0.5 3.8 0

-0.1 3.8 3

/ BLADE 1, PROFILE 2, PRESSURE SIDE

3

0.0 10.2 -3

0.5 10.2 -2

1.0 10.2 0

2

1.0 10.2 0

0.1 10.2 3

/ BLADE 1, PROFILE 2, SUCTION SIDE

3

0.0 10.2 -3

-0.5 10.2 -2

-1.0 10.2 0

2

-1.0 10.2 0

-0.1 10.2 3

/

/ BLADE 2 (SPLITTER)

2

2


2 1 0

/ BLADE 2 (SPLITTER), PROFILE 1, PRESSURE SIDE

3

1.0 3.8 -2

1.1 3.8 -1.5

1.2 3.8 0

2

1.2 3.8 0

1.1 3.8 2

/ BLADE 2 (SPLITTER), PROFILE 1, SUCTION SIDE

3

1.0 3.8 -2

0.9 3.8 -1.5

0.8 3.8 0

2

Example GAMBIT Turbo File GAMBIT TURBO FILE FORMAT


0.8 3.8 0

0.9 3.8 2

/ BLADE 2 (SPLITTER), PROFILE 2, PRESSURE SIDE

3

2.0 10.2 -2

2.2 10.2 -1.5

2.5 10.2 0

2

2.5 10.2 0

2.1 10.2 2

/ BLADE 2 (SPLITTER), PROFILE 2, SUCTION SIDE

3

2.0 10.2 -2

1.8 10.2 -1.5

1.5 10.2 0

2

1.5 10.2 0

1.9 10.2 2

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