Turbo

Multistage Unsteady Turbomachinery Analysis Code – TURBO

Code Description

The current version of the code is an extension of TURBO Parallel Version 4 [1]. It is a MPI (Message Passage Interface) implemented multi-block, structured, turbomachinery flow simulation code capable of treating general multi-stage configurations, by solving the 3-D compressible unsteady Reynolds-Averaged Navier-Stokes (URANS) equations in Cartesian coordinate system.

The code was developed at Mississippi State University with support from NASA Glenn Research Center, U.S. Army Research Office, GE Aircraft Engines, and Honeywell Engines Systems and Services. The governing equations are solved in the relative frame of reference with the velocity vector cast in the absolute frame basis. They are discretized with an implicit time marching cell-centered finite volume formulation, and the solution algorithm for the non-linear algebraic equations is the Newton’s method. A symmetric Gauss-Seidel relaxation scheme is used for the matrix solution in each of the Newton’s iteration. A characteristics-based flux-vector splitting high order upwind scheme is employed for the convection terms.

Models and Features

The turbulence model used in the code is the 2-equation CMOTT k-ε model [2] developed at NASA GRC. Real gas effect is modeled with variable specific heat ratio as a function of temperature via lookup table. Simulation can be performed in full annulus (complete wheel of each blade row), periodic sector (multiple passages per blade row), or phase lag (single passage per blade row) mode. Purge flow is treated as an additional source term to the equations. If desired, a clearance model is also available for modeling tip and hub clearance flows. In addition to the standard output of PLOT3D format, flow solution can also be written in APNASA format that many of the APNASA post processing tools can be used for analysis. Aeroelasticity analysis of fans is performed with a set of supporting codes, collectively known as TURBO-AE, together with the TURBO code [3].

Applications

TURBO/TURBO-AE has been widely accepted in aerodynamic and aeroelastic analysis of multistage turbomachinery flows, for example, in compressor stall management, unsteady aerodynamic analysis of axial and radial compressors, turbine heat transfer, and flutter analysis of fans. Full annulus simulations of fans of modern design by GE and Honeywell with bypass flow path were performed satisfactorily at NASA GRC in the analysis of the effects of inlet flow distortion on the fans’ performance. More recently, it was used in the analysis of NASA BLI2DTF fan (designed by UTRC) with inlet flow distortion type 1. Large-scale computation of up to 300 processors with as much as 122 million grid points has been performed.

References

1. Chen, J.P. and Briley, W.R., “A Parallel Flow Solver for Unsteady Multiple Bladerow Turbomachinery Simulations,” ASME-2001-GT-0348, 2001.
2. Zhu, J. and Shih, T.H., “CMOTT Turbulence Module for NPARC,” NASA Report No. CR 204143, 1997.
3. Srivastava, R., Bakhle, M., and Keith, T.G., “Numerical Simulation of Aerodynamic Damping for Flutter Analysis of Turbomachinery Blade Rows,” Journal of Propulsion and Power, pp. 260-267, Vol. 19, No. 2, 2003.

Point of Contact

Dr. Mark Celestina  216-433-5938