WHAT IS XLTRC2?
XLTRC2 is a suite of very fast, accurate and experimentally verified, and user-friendly codes for executing a complete lateral and torsional rotordynamic analysis of rotating machinery including pumps, compressors and turbines. Extensive help files are provided for the base and support-library codes. SI or US units can be used interchangeably. XLTRC2 is bundled with no less than twenty five examples of rotordynamic analysis including rotors for compressors, pumps and gas turbines, each model featuring distinctive bearing/seal support conditions and displaying unique characteristics of rotordynamic behavior.
XLTRC2 runs on Windows XP, Vista and Win7, and Microsoft Excel 2003, 2007 and 2010 versions. XLTRC2 also runs on 64-bit Windows operation systems, while maintaining backward compatibility with older systems.
HOW DOES XLTRC2 WORK?
For lateral rotordynamics, XLTRC2 uses a Timoshenko beam, finite-element formulation to model the rotor and housing elements to any degree of accuracy that the analyst feels appropriate. Model dimensionality and execution time are dramatically reduced by using real, zero-running speed modes in a component-mode synthesis formulation. By using real modes (instead of complex modes) the initial modal calculation time is minimized (dramatically), and interpolation and extrapolation of modal parameters is eliminated.Constraint modes are used only at bearing locations and connection points that require nonlinear or frequency-dependent force or moment impedances. XLTRC2 generates rotordynamic results faster than most experienced engineers can input data and evaluate results. Stated differently, engineers don’t wait on XLTRC2.
WHAT ADVANCED FEATURES DOES XLTRC2 PROVIDE?
The following capabilities and features are provided for lateral rotordynamic analysis:
• Steady state rotor response due to base harmonic motion. This feature allows calculation of steady state rotor response of a rotor due to motion of an off-shore oil platform, for example.
• Multi-rotor/housing models can be easily developed including dual-rotor “shaft-in-shaft” systems.
• Housings that are not adequately modeled by a beam model can be modeled directly by ANSYS, and the resultant component-mode output directly loaded into XLTRC2 for analysis.
• General linear transfer-function matrices can be used directly to model reaction elements versus (shaft speed dependent) stiffness and damping coefficients: e.g., the transfer function of a magnetic bearing is readily and directly accepted. Force (2×2) and combined force and moment (2×2) transfermatrices are accepted.
• Reaction-load/motion transfer-functions are accepted with sensor measurements of motion at one location and force application at another location.
• The influence of bearings and seal misalignments can be directly modeled. For a statically indeterminate rotor, a bearing or seal can be arbitrarily misaligned, changing the bearing loads and (for a hydrodynamic bearing) changing the rotordynamic coefficients and response.
• Rotor Response due to bent-shaft excitation.
• Rotor response and housing acceleration levels due to base excitation. This feature can be used to easily calculate relative rotor response and housing acceleration levels for a compressor on a moving off-shore platform.
• Rotor response can be calculated due to prescribed base maneuver motion. This feature can be used to calculate rotor deflections and bearing loads of aircraft gas turbine rotors due to the mass-center acceleration and pitch, yaw, and roll of the aircraft.
• Bending stresses can be calculated using the bending moments and the shaft sectional modulus. Three maximum bending stresses are reported corresponding to static load, forward whirl imbalance loading and reverse whirl imbalance loading.
• A time-transient nonlinear feature is available to analyze the influence of nonlinearities such as bearing dead bands, rubbing, hydrodynamic cylindrical journal bearings and squeeze film dampers, etc. Blade loss phenomena, limit-cycle motion of vertical pumps, etc. can be analyzed. An automated time transient response calculation tool helps to perform multiple cases at one time.
• User-defined nonlinear connections can be handled using user defined DLLs (dynamic linked libraries).
• External torques, constant or time varying, can be specified for each shaft to simulate transient shaft motions during start-up and run-down. Responses to (sudden) imbalances can be readily obtained for rotors supported on fluid.