Study on the Non-uniform Distribution Characteristics of Oil Mist and Local Ventilation Method in Machining Workshop

Abstract

Oil mist pollution in machining workshops poses risks to worker health, equipment reliability, and operational safety. This study characterizes the non-uniform spatial distribution of oil mist and proposes an optimized local ventilation strategy. Field measurements of oil mist concentration and airflow velocity were conducted in a 14 m × 12 m × 5 m workshop at a precision equipment factory in Zhuzhou, Hunan. A computational fluid dynamics (CFD) model, employing the RNG k–ε turbulence model and a bidirectional coupled discrete phase model (DPM), was developed to simulate oil mist transport and dispersion. The numerical results were validated against field data obtained using TSI-8386 hot-wire anemometers and TSI-8530 DustTrak particle monitors, with deviations within 20%. Systematic analysis of the concentration distribution along the Z, Y, and X directions revealed a distinct non-uniform pattern. High-concentration oil mist was primarily clustered in mid-height hollow zones (2–3 m, average concentration of 0.715 mg · m −3 ), near-wall regions, and low-velocity vortex zones. Although the average concentration in the breathing zone \(Z=1.5 m\) was 0.354 mg · m −3 , which is below the permissible limit, localized high-concentration clusters were observed. Based on these spatial characteristics, a targeted local ventilation strategy was formulated. Eight directional exhaust outlets were installed within four key high-concentration regions in worker activity and breathing zones, forming an optimized and energy-efficient ventilation configuration. The results demonstrate that this measure reduced the overall average oil mist concentration in the workshop by 20.4%, decreased the concentration in the breathing zone by 29.7%, and achieved a 55.7% reduction in the corridor area. Importantly, this was accomplished while reducing total energy consumption by 21.7%. By improving air quality in worker activity zones without increasing air supply volume, this strategy provides a scientific and engineering reference for controlling oil mist pollution, contributing to the safe, green, and sustainable development of the manufacturing industry.