Session: 37-07 Radial - Performance 2

Submission Number: 177871

Impact of Inlet Flow Pulsations on Performance of Centrifugal Compressors and Impact on its Design 

Ocean-going vessels powered by two-stroke engines increasingly rely on Exhaust Gas Recirculation (EGR) systems to meet stringent IMO Tier III emissions regulations. These systems incorporate centrifugal compressors—EGR blowers—that operate under highly unsteady conditions due to pulsating inlet flows from engine exhaust cycles. Traditional compressor designs, based on steady-state assumptions, have shown performance limitations under such conditions, particularly in reduced mass flow and increased aerodynamic loading.

This paper investigates the impact of inlet flow pulsations on centrifugal compressor performance using both steady and transient Computational Fluid Dynamics (CFD) simulations.

The study compares two generations of EGR compressors: the first-generation is designed using conventional steady-state methods, whereas the second-generation is developed with new design rules that account for unsteady flow phenomena. Transient CFD-RANS simulations were conducted using Ansys CFX, incorporating realistic boundary conditions derived from engine test data. The simulations reveal that transient-averaged losses in the diffuser and volute are significantly higher than those predicted by steady-state models. These losses are attributed to complex flow interactions, including backflow regions.

The new design demonstrates improved aerodynamic stability and reduced sensitivity to pressure fluctuations. Comparative analysis shows that the new design achieves higher isentropic efficiency, greater mass flow capacity, and more stable operation near surge conditions.

This work provides a foundational framework for designing centrifugal compressors capable of operating efficiently and reliably under the pulsating flow conditions inherent in modern marine EGR systems. The insights gained are applicable not only to marine propulsion but also to other turbomachinery applications where unsteady inlet conditions prevail.

Presenting Author: Simon Stummann Howden Turbo GmbH

Presenting Author Biography: After graduating in Mechanical Engineering from Technical University Kaiserslautern, Dr.-Ing. Simon Stummann completed his PhD at RWTH Aachen University, focusing on jet propulsion and turbomachinery, in particular penny cavities of high pressure compressors in jet engines. In 2018, he joined Howden Turbo GmbH, progressing from R&D Engineer and Project Manager to Team Lead for Research & Development Turbo Products. He led global product development, managed successful product relocations, contributed to sales growth, and patented new designs. His expertise includes aerodynamic optimization, team leadership, and driving technology strategy.

Authors:

Simon Stummann Howden Turbo GmbH
Matthias Schleer Howden Turbo GmbH
Shreman Parikh Howden Turbo GmbH