Multi-Scale Modeling of Rotating Stall & Geometric Optimization – Part B

Project Description

Compression of carbon dioxide plays a key role in two Department of Energy technology areas; carbon capture and sequestration, and power systems using super-critical CO2 as a working fluid. Efficient and reliable compression of CO2 requires re-evaluating existing rotary machinery concepts. Stable operation of rotating machinery is essential to avoiding expensive service operations, and must be considered in the design phase of complex turbo-machinery system. Currently, engineers utilize a set of empirically derived correlations to evaluate the stability regimes. However, these correlations are constrained to systems with large stability margins, specific geometry configurations, and process type. New technology developments, including high-pressure ratio, single-stage machines with higher mole weight working fluids and large coefficient designs, are compelling engineers to reevaluate these correlations.
The goal of this project is to evaluate models used by industry for stability. The advanced simulation capabilities of Titan will be used to perform baseline full-annulus, tine-accurate computational fluid dynamic (CFD) simulations of unshrouded centrifugal impellers with varying eccentricities (axis of rotation offset from machine axis) and whirl angular velocity. The results will be compared to aerodynamic cross- coupling coefficients from carious empirical models such as axial machines or shrouded compressors. Direct comparison will highlight the strengths, deficiencies and applicability of these empirical models. The data obtained from these simulations will help in developing models for unshrouded compressor designs. This understanding will be published for the entire technical community, and will be used to accelerate the development of super-critical CO2 turbo machinery for both carbon sequestration and advanced power generation,