FLFACT
Bulk Data Entry Used to specify the aerodynamic factors in aerodynamic flutter analysis.
The aerodynamic factors are:
- Density ratios
- Mach numbers
- Reduced frequencies
- Velocities
Format 1
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
|---|---|---|---|---|---|---|---|---|---|
| FLFACT | ID | F1 | F2 | F3 | F4 | F5 | F6 | F7 | |
| F8 | F9 | etc. | etc. | etc. |
Format 2
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
|---|---|---|---|---|---|---|---|---|---|
| FLFACT | ID | F1 | THRU | FNF | NF | FMID |
Example 1
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
|---|---|---|---|---|---|---|---|---|---|
| FLFACT | 1002 | 0.1 | 0.56 | 1.01 | 4.0 |
Example 2
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
|---|---|---|---|---|---|---|---|---|---|
| FLFACT | 1003 | 0.120 | THRU | 0.550 | 10 | 0.26 |
Definitions
| Field | Contents | SI Unit Example |
|---|---|---|
| ID | Unique identification number. No default (Integer > 0) |
|
| Fi | Aerodynamic factor value.
No default (Real) |
|
| FNF | Final aerodynamic factor value. Required when Format 2 is used. No default (Real) |
|
| NF | Number of aerodynamic factors. Required when Format 2 is used. No default (Integer > 0) |
|
| FMID | Intermediate aerodynamic factor value. 5
6 Required when Format 2 is used. No default (Real) |
Comments
- The FLFACT Bulk Data Entry must be referenced by a FLUTTER Bulk Data Entry. Unreferenced FLFACT entries will be ignored during the analysis.
- Multiple FLFACT entries can point to the same FLUTTER Bulk Data Entry.
- Each FLFACT entry must contain data of only one type of aerodynamic factor.
- The order of the factors in the FLFACT entries determines the order in which they will be used withing the looping of aerodynamic flutter analysis.
- When Format 2 is used,
FMID must lie between F1 and
FNF.F1(FNF−FMID)(NF−i)+FNF(FMID−F1)(i−1)(FNF−FMID)(NF−i)+(FMID−F1)(i−1)
Where, i = 1, 2, …, NF.
- When Format 2 is used, the value
of FMID determines the distribution of the factors.
- If FMID = (F1+FNF)2 , the factors are equally distributed between F1 and FNF.
- Otherwise, the factors are unequally distributed and will be concentrated around FMID.
- If METHOD = PK in the FLUTTER definition and if a FLFACT is used to specify velocities, then the velocities must be non-zero.
- If METHOD =
PK or PKNL in the
FLUTTER definition:
- Entering negative values produces eigenvector results at a velocity equal to the positive value of the input.
- Entering positive values produces eigenvalue results without eigenvectors.