Benchmarking CD-Adapco’s Star-CCM+ in a Production Design Environment

It has been well-known that many industrial applications that use centrifugal compressors have continuously demanded for more and more efficient machines in the past decade or so. However, the current market trend indicates that there is a strong demand among the end users for reduced delivery times of these efficient compressors. This, in turn, requires that the aerodynamic design of highly efficient centrifugal stages be completed within shorter time frames. In order to meet these challenges, it is mandatory to involve modern computational analysis tools such as Computational Fluid Dynamics (CFD) as a routine design tool for the aerodynamic engineer. This presentation discusses a hierological structure for CFD analysis along with an overview of limitations and benefits for each classification within this structure. Usage and results pertaining to the implementation of this structure at Cameron’s Compression System will also be covered. Accordingly, a discussion of aerodynamic design practices (both current and historical) will be offered. It should be obvious to the reader that the goal of design integration would require the primary focus to be towards validation of the commercial CFD code. Results presented were obtained using the StarCCM + CFD package developed by CD-Adapco. As mentioned earlier, CFD analysis can be described as a hierological structure consisting of 4 levels. At level 1, the analysis component consists of an impeller coupled with a vaneless diffuser region under a steady state flow condition. On level 2, the model involves an impeller and low solidity diffuser row analysis using a mixing plane interface. Level 3 facilitates the consideration of entire impeller and an entire diffuser with a full set of diffuser blades within a transient framework. These levels (1 through 3) include the assumption of a dump collector and imply a circumferential periodicity at the exit. Also, models for level 2 and level 3 incorporate the use of a 1-d modeling to predict overall stage performance. Level 4, the most sophisticated model, involves a full-stage analysis of an unsteady turbulent flow through the entire centrifugal stage, all the way from impeller inlet to the discharge of the scroll/volute/collector. At this level, the overall stage performance is predicted directly from the CFD analyses. The paper compares the results of each level of analyses with the test data and discusses the potential benefits as well as limitations of each level of analyses.