Thermoelectric coupling study of scavenging pressure effect on fuel spray and mixing of a vibratory combustion linear engine

Abstract

The vibratory combustion linear engine is a promising energy converter that transforms thermal energy from fuel combustion into electrical energy through mechanical vibration. However, the effect of scavenging pressure on fuel spray and mixture formation under complex coupling conditions remains underexplored. To address this, a thermoelectric coupling model was developed to simulate the impact of scavenging pressure on mixture formation by integrating vibration, scavenging, power generation, and combustion, then updates the computational results of vibration and combustion calculations with an iterative algorithm to accurately simulate the effect of scavenging pressure on the mixture formation characteristics. Results show that scavenging pressure affects engine vibration, compression ratio, and fuel injection conditions. At a scavenging pressure of 1.1 bar, the fuel evaporation rate is 98.98%, the mixing uniformity index is 58.12%, and turbulence kinetic energy is 7.11 m²/s². As scavenging pressure increases, the mixing uniformity decreases. Meanwhile, turbulence kinetic energy and fuel evaporation rate initially increase and reach their peak around 1.4 bar, after which they begin to decrease due to increased resistance to the fuel spray at higher pressures. Increased scavenging pressure enhances airflow momentum, improving atomization and spray penetration, while prolonging ignition delay. This delay provides more time for atomization, evaporation, and mixing before combustion, ultimately improving mixture quality.