Session: 19-03 Radial High Speed Compressors & Turbines

Paper Number: 102869

102869 - Study of the Variation in Component Level Characteristics of a Centrifugal Compressor Across the Compressor Map Using Cfd and Experiments With Detailed Instrumentation on a Gas Stand 

A compressor map with variations in component level characteristics is introduced. This new approach to plot component level characteristics helps understand the behavior of critical design parameters such as velocity triangles, pressure coefficients, and loss coefficients across the entire compressor map along with the conventional performance parameters. Compressor design these days involves a significant amount of CFD, but the importance of 1D design and analysis is overshadowed by 3D CFD, both steady RANS and unsteady RANS/LES/DES. While the authors support the development of such advanced computational tools,  validating these computational results with experimental measurements is essential. Most of the design and analysis work on centrifugal compressors available in the literature is limited to using the entire compressor stage (flange-to-flange) as a black box in order to assess performance. The few detailed analyses that are found study either a single design point or very few points closer to the design point on the compressor map. Due to the lack of component level characteristics, it is difficult to estimate pressure and loss coefficients on the components and also understand the coupling of different components and their respective interactions. This, in turn, forces the turbomachinery community to rely on CFD models that are not validated.

This paper addresses the above-mentioned problems by plotting the vital component level parameters on a typical compressor map with the mass flow on the abscissa and pressure ratio on the ordinate, providing deeper insights on the crucial regions of operation, including design point and off-design points. Detailed instrumentation of the compressor stage components such as wheel, diffuser and volute with static pressure measurements and Kiel probes were carried out to capture the flow field experimentally on Scania’s Gas stand. CFD studies with the same compressor geometry were conducted to generate computational results of the flow field. In addition, the results from the computations were correlated and validated with the experimental test results.

Based on these validated results, the component characteristics are studied in detail. This provides better insights on the selection of the right components for optimal performance and also guides redesign of specific components and not the whole stage. In addition, the unsteady characteristics, such as the onset of stall instabilities, could be spotted from a steady state plot. The plots introduced in this paper could aid design decisions at a 1D level and point out the limitations of the different components of the centrifugal compressor stage.

Presenting Author: Janakiraman Thiyagarajan Scania CV AB

Presenting Author Biography: Janakiraman is currently an Industrial PhD student at Scania R&D working together with Lund Technical University and KTH. Previously, he worked as an Aerodynamic Design Engineer at Scania R&D and has also held different roles at other Aerospace firms. He holds a Double Master in Turbomachinery Aeromechanics and Aerospace Engineering.

Authors:

Janakiraman Thiyagarajan Scania CV AB
Carl Fredriksson Scania CV AB
Nicholas Anton Scania CV AB
Jens Fridh KTH Royal Institute of Technology
Magnus Genrup Lund University