3. Operands

3.1. Keyword VITE_FLUI

Keyword factor that defines the range of fluid velocities studied and the discretization.

First speed value for which the coupling parameters are calculated.

The last speed value for which the coupling parameters are calculated.

Define the number of speed points (the discretization step is constant).

3.2. Keyword BASE_MODALE

♦ BASE_MODALE

Keyword factor that defines the modal basis of the mode_meca concept for which the coupling parameters are calculated. Coupling changes the natural frequencies and the values of the reduced damping terms associated with each mode (keyword AMOR_REDUIT or AMOR_UNIF).

♦ MODE_MECA = fashion

Modal basis for the mode_meca concept type.

◊ NUME_ORDRE = l_nuor

Allows you to select the modes of the modal base of the mode_meca type to be taken into account for the calculation of the coupling.

◊/AMOR_REDUIT = l_amor

List of reduced depreciations (percentage of critical depreciation) corresponding to each mode of the structure.

Note:

They must be the same number as the number of modes taken into account (these modes are defined by the keyword NUME_ORDRE) .

/AMOR_UNIF = love

The same reduced damping is applied to all the modes of the modal base.

◊ AMOR_REDUIT_CONN = l_amor_c

List of reduced depreciations (percentage of critical depreciation) corresponding to each mode of the structure for the Connors method (see [R4.07.04]). According to this reference documentation, two Connors instability ratio values are provided (including one called « All Components »).

Note:

As for the keyword AMOR_REDUIT, they must be the same number as the number of modes taken into account.

3.3. Keyword TYPE_FLUI_STRU

♦ TYPE_FLUI_STRU = typeflui

Type_flui_stru type concept. It makes it possible to define the configuration studied, that is to say the coupling coefficients used for modeling fluid-elastic forces.

Note:

In the case of a configuration of the « bundle of tubes under axial flow » type (keyword factor FAISCEAU_AXIAL ), the calculation of the coupling parameters of the structure with the fluid in a state of rest is taken into account. This calculation is made regardless of the fluid speed range that the user has entered with the keyword VITE_FLUI .

In this case of a fluid at rest, the transfer matrix representing the fluid-elastic force exerted on the structure takes the form of an added damping matrix.

3.4. Keyword IMPRESSION

◊ IMPRESSION

Keyword factor allowing the user to choose what information they want to have written in the RESULTAT file.

◊ PARA_COUPLAGE = 'OUI' or 'NON'

With this keyword, the user can request the printing of result tables giving, for each mode, the changes in reduced speed, frequency and reduced modal damping as a function of the fluid flow speed. The value by default is” OUI “.

◊ DEFORMEE = 'OUI' or 'NON'

With this keyword the user can request the printing in “RESULTAT” format of the displacement fields corresponding to the modal deformations. The value by default is” NON “.

3.5. Operand STOP_ERREUR

◊ STOP_ERREUR = stop

Keyword that allows you to define the behavior of the code in the event of a convergence problem in the calculation of coupling coefficients for a given speed and a mode of deformation of the structure.

If STOP_ERREUR =” OUI “, the code stops with a fatal error in the event of a convergence problem by notifying the user of the speed concerned.

If STOP_ERREUR =” NON “, the code emits an alarm notifying the user of the convergence problem (speed and mode number) and stores the last value calculated for the coupling coefficients.