A validated numerical model was established to simulate gas−liquid flow behaviors in the oxygen-enriched side-blown bath furnace.This model included the slip velocity between phases and the gas thermal expansion effec...A validated numerical model was established to simulate gas−liquid flow behaviors in the oxygen-enriched side-blown bath furnace.This model included the slip velocity between phases and the gas thermal expansion effect.Its modeling results were verified with theoretical correlations and experiments,and the nozzle-eroded states in practice were also involved in the analysis.Through comparison,it is confirmed that the thermal expansion effect influences the flow pattern significantly,which may lead to the backward motion of airflow and create a potential risk to production safety.Consequently,the influences of air injection velocity and furnace width on airflow behavior were investigated to provide operating and design guidance.It is found that the thin layer melt,which avoids high-rate oxygen airflow eroding nozzles,shrinks as the injection velocity increases,but safety can be guaranteed when the velocity ranges from 175 to 275 m/s.Moreover,the isoline patterns and heights of thin layers change slightly when the furnace width increases from 2.2 to 2.8 m,indicating that the furnace width shows a limited influence on production safety.展开更多
This paper presents a detailed analysis of the complex flow beneath two impinging jets aligned with a low-velocity crossflow which is relevant for the future F-35 VSTOL configuration, and provides a quantitative pictu...This paper presents a detailed analysis of the complex flow beneath two impinging jets aligned with a low-velocity crossflow which is relevant for the future F-35 VSTOL configuration, and provides a quantitative picture of the main features of interest for impingement type of flows. The experiments were carried out for a Reynolds number based on the jet exit conditions of Rej = 4.3 × 10^4, an impingement height of 20.1 jet diameters and for a velocity ratio between the jet exit and the crossflow VR = V/Uo of 22.5. The rear jet is located at S = 6 D downstream of the first jet. The results show a large penetration of the first （upstream）jet that is deflected by the crossflow and impinges on the ground, giving rise to a ground vortex due to the collision of the radial wall and the crossflow that wraps around the impinging point like a scarf. The rear jet （located downstream） it is not so affected by the crossflow in terms of deflection, but due to the downstream wall jet that flows radially from the impinging point of the first jet it does not reach the ground. The results indicate a new flow pattern not yet reported so far, that for a VSTOL aircraft operating in ground vicinity with front wind or small forward movement may result in enhanced under pressures in the aft part of the aircraft causing a suction down force and a change of the pitching moment towards the ground.展开更多
The technique of the use of multi-annular opposed jets as different from using swirl and bluff body creates an excellent recirculation zone with desired size in a large space.The size of recirculation,the magnitude of...The technique of the use of multi-annular opposed jets as different from using swirl and bluff body creates an excellent recirculation zone with desired size in a large space.The size of recirculation,the magnitude of reverse velocity and turbulence intensity are much greater than those formed by bluff body.Factors affecting the flowfield include the velocity ratio of the opposed jets to the primary air J,the diameter and construction of the opposed jet ring,secondary air velocity and configuration,and confined or unconfined flow condition and so on.This method is a promising way for flame stabilization in combustion technology.展开更多
基金the support from the National Key R&D Program of China(No.2018YFC1901606).
文摘A validated numerical model was established to simulate gas−liquid flow behaviors in the oxygen-enriched side-blown bath furnace.This model included the slip velocity between phases and the gas thermal expansion effect.Its modeling results were verified with theoretical correlations and experiments,and the nozzle-eroded states in practice were also involved in the analysis.Through comparison,it is confirmed that the thermal expansion effect influences the flow pattern significantly,which may lead to the backward motion of airflow and create a potential risk to production safety.Consequently,the influences of air injection velocity and furnace width on airflow behavior were investigated to provide operating and design guidance.It is found that the thin layer melt,which avoids high-rate oxygen airflow eroding nozzles,shrinks as the injection velocity increases,but safety can be guaranteed when the velocity ranges from 175 to 275 m/s.Moreover,the isoline patterns and heights of thin layers change slightly when the furnace width increases from 2.2 to 2.8 m,indicating that the furnace width shows a limited influence on production safety.
文摘This paper presents a detailed analysis of the complex flow beneath two impinging jets aligned with a low-velocity crossflow which is relevant for the future F-35 VSTOL configuration, and provides a quantitative picture of the main features of interest for impingement type of flows. The experiments were carried out for a Reynolds number based on the jet exit conditions of Rej = 4.3 × 10^4, an impingement height of 20.1 jet diameters and for a velocity ratio between the jet exit and the crossflow VR = V/Uo of 22.5. The rear jet is located at S = 6 D downstream of the first jet. The results show a large penetration of the first （upstream）jet that is deflected by the crossflow and impinges on the ground, giving rise to a ground vortex due to the collision of the radial wall and the crossflow that wraps around the impinging point like a scarf. The rear jet （located downstream） it is not so affected by the crossflow in terms of deflection, but due to the downstream wall jet that flows radially from the impinging point of the first jet it does not reach the ground. The results indicate a new flow pattern not yet reported so far, that for a VSTOL aircraft operating in ground vicinity with front wind or small forward movement may result in enhanced under pressures in the aft part of the aircraft causing a suction down force and a change of the pitching moment towards the ground.
文摘The technique of the use of multi-annular opposed jets as different from using swirl and bluff body creates an excellent recirculation zone with desired size in a large space.The size of recirculation,the magnitude of reverse velocity and turbulence intensity are much greater than those formed by bluff body.Factors affecting the flowfield include the velocity ratio of the opposed jets to the primary air J,the diameter and construction of the opposed jet ring,secondary air velocity and configuration,and confined or unconfined flow condition and so on.This method is a promising way for flame stabilization in combustion technology.
