BALANCING

LTSQAP [PC]
This program employs the least squares method for error balancing based on the calculation of system influence coefficients. It can handle up to 5 unbalance planes, 10 speeds, 10 probes and accounts for residual run-out or shaft bow. ROMAC Report No. 71.

BALOPT [PC]
Balopt-This state of the art program provides multiplane and multispeed capabilities with the options of least squares or min-max balancing solutions. Influence coefficients can either be calculated or user-specified. Runout compensation and constraint capabilities are included. Practical constraints can be handled through weighting or directly specified such as response amplitude or maximum correction weight. Correction weight splitting is also available.

BEARING ANALYSIS

DAMBRG2 [PC]
DAMBRG2 calculates dynamic coefficients, power losses, and rigid rotor stability information for two-lobe isoviscous bearings with a pressure dam in only one pad. Opposite to the dam the user may specify the presence of a track. The code solves the two-dimensional Reynolds Equation including an optional linearized turbulence model. ROMAC Report No. 97.

HYDROBRG [PC]
HYDROBRG predicts the steady-state and dynamic operating characteristics for hybrid journal bearings where hydrostatic and hydrodynamic effects are present. The operating characteristics predicted by the program include the film thickness distribution, film pressure distribution, shaft position, load capacity, stiffness and dampings. The analysis can include effects due to cavitation. A finite element method is used. Axial grooves may be present as well as different pocket geometries on each pad. Pocket discharge orifice coefficients are calculated internally. ROMAC Report No. 511.

PDAM2D [PC]
A multiple pad pressure dam bearing can be analyzed by this program. The geometry of each pad can be different as specified by the user. It calculates the journal equilibrium position, linearized stiffness and damping coefficients, and rigid rotor stability threshold. The full two dimensional Reynolds equation is solved for each pad. This program is an extension of DAMBRG2 which solves for a bearing with a single pressure dam. ROMAC Report No. 228. 

SQFDAMP [PC]
This program determines stiffness and damping coefficients for short and long squeeze film bearings with and without fluid film cavitation. ROMAC Report No. 11.

SFDNL [PC]
The program is an advanced analysis for squeeze film damper. The analysis is based on the finite element method to solve the fluid properties.SQBUBL included the air entrainment in the lubricant. The air bubbles are included by the modification of the total viscosity and density properties of the fluid. The code also conducts a transient analysis. The output of the code is the displacement, velocity and damper forces as function of time. ROMAC Report No. 561.

THBRG [UNIX & PC]
THBRG calculates the pressure profiles, temperature distribution in film and bearing housing, lubricant flow rates, power loss, and dynamic coefficients for a multilobe journal bearing with an incompressible lubricant. A combination of finite element and finite difference methods are used to solve the governing equations. THBRG uses an assumed axial pressure profile and an assumed cross-film viscosity variation to decrease the dimensionality of the problem to the circumferential direction only. This significantly increases the speed of the program while retaining high accuracy. The analysis includes fluid film conduction, cross-film viscosity variation, two-phase cavitation models for the energy equation, conduction in the housing, convection heat transfer from housing and turbulence. ROMAC Report No. 273.

THPAD [PC]
THPAD calculates the pressure profiles, temperature distribution in film and bearing components, lubricant flow rates, power loss, and dynamic coefficients for a tilting pad journal bearing with an incompressible lubricant. A combination of finite element and finite difference methods are used to solve the governing equations. THPAD uses an assumed axial pressure profile and an assumed cross-film viscosity variation to decrease the dimensionality of the problem to the circumferential direction only. This significantly increases the speed of the program while retaining high accuracy. The analysis includes pad mechanical and thermal deformations, journal thermal deformation, fluid film conduction, cross-film viscosity variation, pivot deformation, two-phase cavitation models for the energy equation, and turbulence. ROMAC Report No. 284.

MAXBRG [UNIX & PC]
MAXBRG is a 2-D finite element code that performs steady state TEHD analysis for fluid film journal bearings. It is able to analyze a wide variety of bearings including fixed geometry, pressure dam and tilting pad bearings. Special models are applied for directed lubricated tilting pad bearings which employ grooves or spray bars. In addition to the normal flooded oil feed condition, starvation can be examined as well as axial flow and high ambient pressure conditions.

THRUST [UNIX & PC]
THRUST predicts the steady-state operating characteristics of tilting-pad and fixed geomety fluid-film thrust bearings. The operating characteristics predicted by the program include the film thickness distribution, film temperature distribution, pad and runner temperature distribution, power losses, flow requirements, and pad and runner elastic deformation. The analysis includes effects due to cavitation, turbulence, cross-film viscosity variation, centrifugal inertia, temperature and pressure dependent viscosity, crowns, and detailed pad models. ROMAC Report No. 376.

 THRUST Brochure

CRITICAL SPEED (UNDAMPED)

CRTSP2 [PC]
CRTSP2 calculates the undamped planar critical speeds of dual-level rotor systems using the transfer matrix method. The method includes rotary inertia, shear deformation, circularly symmetric gyroscopic, and lumped inertia effects. Both translational and rotational springs may couple the rotors or tie the rotors to ground. Rotor model and modeshape plots are possible. A critical speed plot may also be produced if more than one bearing configuration is considered. CRTSP2 may be used to produce the modal input for other codes such as FRESP2 and COTRAN. ROMAC Report Nos. 60 and 103.

MODFR2 [PC]
MODFR2 is used to determine the undamped planar critical speeds of single or dual level rotor systems using the finite element modeling method. The approach includes rotary inertia, lumped inertia effects, translational and rotational springs, lumped and consistent mass options, but does not include gyroscopic effects. MODFR2 can be run with or without coupling the rotor system to ground and, therefore, is ideally suited to producing the modal input for other codes such as FRESP2 and COTRAN. ROMAC Report No. 291.

TWIST2 [UNIX & PC]
Program TWIST2 calculates the undamped torsional natural frequencies and mode shapes for single shafts, geared shafting with branching, or looped systems. The finite element method is used to obtain the set of equations governing the motion of the system. The program also determines the steady-state forced response characteristics of the system from harmonic torsional input using modal analysis. In the forced response calculations, damping may be added to the system through modal damping ratios or discrete dampers. The input torque magnitudes and phases may be specified as a function of excitation frequency. In addition, several modeling features such as disk models and the "degree rule" are included. ROMAC Report No. 290.

FORCED RESPONSE

FRESP2 [PC]
This program is a modal frequency response program for analyzing the forced response of a dual rotor system with flexible substructure. The program allows the user to analyze a system with unbalance or generalized forces on the rotor, or general forces, displacements, or accelerations applied to the substructure. Generalized speed dependent coupling coefficients are used to represent bearings, seals, and aerodynamic cross-couplings. ROMAC Report Nos. 210 and 218. (Report 210 is the program user's manual, 218 is the program listing.)

RESP2V3 [PC]
This program calculates the non-planar synchronous unbalance response of dual-level multimass flexible rotors (or rotors with flexible casing) using a transfer matrix approach. The modeling includes gyroscopic, rotary inertia, shear deformation, and hysteretic damping effects. Speed-dependent linearized bearing coefficients (with linear interpolation by the program as needed) are supported. ROMAC Report No. 81.

SEALS

HCOMB [PC]
This program solves the bulk-flow equations for the adiabatic flow of a compressible gas within a straight-through honeycomb seal. It calculates the leakage and the dynamic coefficients. ROMAC Report No. 425.

LABY3 [UNIX & PC]
LABY3 calculates the leakage flow and dynamic coefficients for compressible fluid straight-through and uniform interlocking type labyrinth seals. Teeth may be specified on the rotor, stator, or both. The method of Iwatsubo, as improved by Childs, is used as the theoretical basis. ROMAC Report No. 344.

SEAL2 [UNIX & PC]
This program calculates steady state load capacity, stiffness and damping coefficients for plain and grooved seals with incompressible turbulent axial flow. (New Version 1.2.) ROMAC Report Nos. 191 and 194.

SEAL3 [PC]
This program uses a bulk fluid flow perturbation analysis to evaluate rotor dynamic coefficients for stiffness, damping and mass coefficients. It can analyze both plain and circumferentially grooved seals. It adds inlet swirl, mass coefficients and surface roughness. ROMAC Report No. 418.

TURSEAL [UNIX & PC]
This program calculates the stiffness and damping coefficients of turbulent flow annular seals or water lubricated bearings using finite elements. Finite length seals and variable circumferential and axial Reynolds numbers are considered. Turbulence coefficients based on the data of Elrod and Ng are utilized through curve fits. The program has also been found to work well for laminar flow. ROMAC Report No. 145.

STABILITY

FSTB3 [UNIX & PC]
This program calculates the stability, damped critical speeds (eigenvalues), and elliptical whirl mode shapes for multi-spool rotor systems. Linearized fixed geometry bearing coefficients, linearized complete tilting-pad bearing models, and/or linearized collocated/non-collocated magnetic bearing models in the form of transfer functions may be used as rotor support mechanisms. The program includes gyroscopic, rotary inertia, shear deformation, and aerodynamic cross-coupling models. ROMAC Report Nos. 294 and 295.

ROTSTB [PC]
This program calculates the stability, damped critical speeds (eigenvalues), and elliptical whirl mode shapes for single spool rotors. Linearized fixed geometry bearing coefficients, linearized complete tilting pad bearing models, and/or linearized collocated/non-collocated magnetic bearing models in the form of transfer functions are allowed. The program supports flexible support models with each bearing type. The program uses the transfer matrix method in non-dimensional form and includes the effects of gyroscopics, rotary inertia, shear deformation, aerodynamic cross coupling, and hysteretic damping. Rotor cross-section and damped mode shape plots are possible. ROMAC Report Nos. 58 and 337.

ComboRotor 1.0Beta [PC]
This program is a comprehensive computer program that performs steady state rotordynamic analysis. In this beta version, ComboRotor generates the undamped critical speed map, conducts the stability and unbalance response analyses. It handles multiple rotors, fixed geometry and tilting pad journal bearings, as well as flexible supports. This beta version essentially combines the most important features of CRTSP2, ROTSTB and FORSTAB in a single code, resulting in higher efficiency. Eventually, it will be expanded to analyze steady state torsional systems and coupled lateral-torsional-axial systems, breaking new grounds for the analytical capabilities of ROMAC rotordynamics software.. ROMAC Report No. 521.

 ROTSTB Brochure

LATERAL TRANSIENT

COTRAN [PC]
Nonlinear time transient program for multi-level rotors with substructure. Program uses modal input from CRTSP2 or MODFR2 to create small order inverse mass and stiffness matrices for master degrees of freedom which are integrated forward in time using Newmark's method. Nonlinearities include hydrodynamic bearings and rubs. (Manual provided on disk with code.)

TORSIONAL TRANSIENT

TORTRAN2 [PC]
This program is a computational tool designed to aid in torsional failure prediction. It computes the following information about the rotor system: rigid body angular velocity and acceleration; rotor startup time; transient angular velocity, torque and stress; and, estimated rotor lifetime. ROMAC Report No. 377.

TORTRAN2 Brochure

TORTRAN3 [PC]
TORTRAN3 is a transient response program for torsional rotor systems. It can analyze rotor systems with non-linear couplings that are driven by synchronous machines, variable frequency drives, or any other torsional forcing function that can be expressed as a function of time or rotor speed. One important feature of TORTRAN3 is its cumulative fatigue analysis. Rotors that undergo large periodic loading, such as synchronous motor driven machines during startup, may fail after a finite number of starts. ROMAC Report No. 399.

MAGNETIC BEARING

EMAG [PC]
The E-core Magnetic Bearing Design Tool (EMAG) is a design optimization tool for radial magnetic bearings. The primary purpose for this software is to reduce preliminary design time of E-core radial AMBs, and provide an optimized bearing geometry that can be further analyzed using finite element codes. By employing a simple circuit model, EMAG eliminates the need for hand calculations and allows for quick design iterations. The user enters AMB input parameters such as target force, shaft diameter, and material properties and the program then optimizes bearing size based on a linear circuit model and certain physical bearing constraints. ROMAC Report No. 542.

MAGAUD [PC]
Magnetic bearing audit package. Includes a number of codes for constructing system models, for assessing actuator performance, for determining system forced response and stability, and for converting measured frequency response functions into equivalent (approximate) transfer functions. A short description of the software included in this package is give below. ROMAC Report No. 406.