Non-intrusive flow and pressure field analysis in compressor mufflers using magnetic resonance velocimetry and integrated pressure estimation

Abstract

The internal flow performance of suction mufflers in reciprocating compressors plays a critical role in determining energy efficiency, yet flow design is often constrained by acoustic considerations. In this study, magnetic resonance velocimetry (MRV) was employed to non-invasively characterize three-dimensional velocity and turbulent kinetic energy (TKE) fields in two suction muffler designs under dynamically matched Reynolds number conditions. To estimate internal pressure distributions, the omni-directional integration (ODI) method was applied to MRV-derived velocity data, using both zero Reynolds stress and isotropic turbulence approaches. Results revealed complex internal flow phenomena-including flow separation, recirculation, and strong secondary flows-along with significant non-uniformities at the inlet and outlet. Incorporating TKE through the isotropic turbulence model yielded a more accurate pressure drop estimate, showing a 31.7% reduction in Model 2 compared to Model 1. These differences were closely tied to local TKE gradients and geometric influences. The MRV measurements also highlight limitations in common assumptions for numerical simulation, suggesting that experimental velocity fields can significantly improve simulation fidelity. Overall, this study demonstrates that the combined use of MRV and ODI offers a powerful non-intrusive approach for velocity and pressure diagnostics in complex internal flows, with direct implications for flow system optimization and compressor energy efficiency.