Air–liquid interactions in a pressure-swirl spray
Abstract The energy transfer between a liquid hollow cone spray and the surrounding air has been studied using both imaging and phase-Doppler techniques. The spray was produced by a pressure-swirl atomizer discharging Jet A-1 fuel at inlet over pressures of Δp =0.5, 1. 0.5, 1.0 and 1.5 MPa into quiescent ambient air. The liquid exits the nozzle as a conical film which thins as it spreads and develops long- and short-wave sinusoidal instabilities with breakup occurring, at the length smaller than that predicted by the inviscid model, to form film fragments and ultimately droplets downstream the spray. The single shot imaging characterised the spray regions of near-nozzle flow, the breakup processes and the developed spray. The phase-Doppler system resolved the three components of velocity and size for the droplet flow as measured on radial profiles for four axial distances from the nozzle exit. A Stokes number, Stk , analysis of the droplets’ response times to the airflow time-scales showed that droplets The formation of the hollow cone spray and the interaction of the fragments and droplets with the air, through viscous drag, induce complex entrained airflows. The airflow was found to be highly anisotropic, fluctuating preferentially in the downstream direction, and spatially varying within three distinct spray regions. The air drag establishes a positive size–velocity correlation of droplets; their Stk reduces with axial distance and increases with droplet size and Δp ; so that Stk ≈1 for 20–40 μm droplets and the largest droplets (80–160 μm, Stk > 10) move ballistically. The spatially resolved mean and turbulent kinetic energies of the air and spectra of the droplet velocity fluctuations are detailed in the paper. These findings are relevant to scientists and engineers modelling the complex two-phase flows. Highlights Liquid discharged at η n ≈40%, forms a conical sheet which breaks by sinuous instabilities. Complex anisotropic airflow induced by the interaction of the hollow cone spray with the air. Droplets Stk ≪ 1 used to estimate the local airflow velocity. The Stokes number, Stk reduces with axial distance and increases with droplet size and Δp . The airflow forms 3 regions featuring different MKE, TKE, mean and rms velocity fields. Graphical abstract [DISPLAY OMISSION]
- 원문이 없습니다.
- DOI : http://dx.doi.org/10.1016/j.ijheatmasstransfer.2018.01.003
- Elsevier : 저널 > 논문
유료 다운로드의 경우 해당 사이트의 정책에 따라 신규 회원가입, 로그인, 유료 구매 등이 필요할 수 있습니다. 해당 사이트에서 발생하는 귀하의 모든 정보활동은 NDSL의 서비스 정책과 무관합니다.
원문복사신청을 하시면, 일부 해외 인쇄학술지의 경우 외국학술지지원센터(FRIC)에서
무료 원문복사 서비스를 제공합니다.
NDSL에서는 해당 원문을 복사서비스하고 있습니다. 위의 원문복사신청 또는 장바구니 담기를 통하여 원문복사서비스 이용이 가능합니다.
- 이 논문과 함께 출판된 논문 + 더보기