The mixing process of pre-evaporated afterburner fuel at different positions upstream of the mixers and airflow was numerically simulated in a straight channel,with semicircular mixer,rectangular mixer,triangular mixe...The mixing process of pre-evaporated afterburner fuel at different positions upstream of the mixers and airflow was numerically simulated in a straight channel,with semicircular mixer,rectangular mixer,triangular mixer and chevron mixer respectively.The effects of vortices generated by mixers on fuel distribution and mixing characteristics were studied.The results show that:(1)The scale,strength and breaking speed of the streamwise vortex and the development speed of normal vortex are different downstream of the four mixers,which accelerate the mixing process of fuel and airflow.(2)The fuel distribution at the outlet of mixers,downstream of straight section and downstream of the crest and trough is mainly affected by secondary flow,the streamwise vortex and the normal vortex respectively.(3)The fuel mixing uniformity downstream of the four mixers is increased by about 80%compared with no mixer.In the limited distance,the mixing performance of chevron mixer is the best,while the triangular mixer is the worst Rectangular mixer has the fastest mixing speed and superior comprehensive performance.In addition,the effect of the channel wall on the mixing process downstream of mixers cannot be ignored.展开更多
Full Navier-Stokes Analyses have been conducted for the flows behind the trailing edge of a lobed forced mixer. The governing equations are derived from the timedependent compressible Navier-Stokes equa tions and disc...Full Navier-Stokes Analyses have been conducted for the flows behind the trailing edge of a lobed forced mixer. The governing equations are derived from the timedependent compressible Navier-Stokes equa tions and discretized in the finite-difference form. A simple two-layer eddy viscosity model has also been used to account for the turbulence. Computed results are compared with some of the velocity measurements using a laserDoppler anemometer (Yu and Yip (1997)). In general, good agreement can be obtained in the streamwise mean velocity distribution but the decay of the streamwise circulation is underpredicted. Some suggestions to the discrepancy are proposed.展开更多
This study proposes a new electromagnetic rectangular mixer, and numerically examines the mixing characteristics of two different electrolyte solutions in the device under a uniform magnetic field. The mixer consists ...This study proposes a new electromagnetic rectangular mixer, and numerically examines the mixing characteristics of two different electrolyte solutions in the device under a uniform magnetic field. The mixer consists of a conduit with electrodes equipped on its top and bottom walls. The difference in the electric potentials applied to the sets of electrodes induces the current. The combination of the induced current and magnetic field yields Lorentz force, resulting in the fluid motion for pumping and mixing of the two different fluids. The numerical simulation is carried out with the use of commercial software CFX. The present numerical model is validated by an existing numerical work. The effect of different variables on mixing efficiency is investigated in many different cases with two different heights of the duct and various input voltages of the electrodes. The current simulation results indicate that the mixing performance can be enhanced by using multiple sets of electrodes and applying higher input voltages（absolute values） to the electrodes.展开更多
基金financial support received from the National Science and Technology Major Project(Project No.2017-Ⅲ-0007-0032)supported by National Defense Science and Technology Innovation Special Zone Project。
文摘The mixing process of pre-evaporated afterburner fuel at different positions upstream of the mixers and airflow was numerically simulated in a straight channel,with semicircular mixer,rectangular mixer,triangular mixer and chevron mixer respectively.The effects of vortices generated by mixers on fuel distribution and mixing characteristics were studied.The results show that:(1)The scale,strength and breaking speed of the streamwise vortex and the development speed of normal vortex are different downstream of the four mixers,which accelerate the mixing process of fuel and airflow.(2)The fuel distribution at the outlet of mixers,downstream of straight section and downstream of the crest and trough is mainly affected by secondary flow,the streamwise vortex and the normal vortex respectively.(3)The fuel mixing uniformity downstream of the four mixers is increased by about 80%compared with no mixer.In the limited distance,the mixing performance of chevron mixer is the best,while the triangular mixer is the worst Rectangular mixer has the fastest mixing speed and superior comprehensive performance.In addition,the effect of the channel wall on the mixing process downstream of mixers cannot be ignored.
文摘Full Navier-Stokes Analyses have been conducted for the flows behind the trailing edge of a lobed forced mixer. The governing equations are derived from the timedependent compressible Navier-Stokes equa tions and discretized in the finite-difference form. A simple two-layer eddy viscosity model has also been used to account for the turbulence. Computed results are compared with some of the velocity measurements using a laserDoppler anemometer (Yu and Yip (1997)). In general, good agreement can be obtained in the streamwise mean velocity distribution but the decay of the streamwise circulation is underpredicted. Some suggestions to the discrepancy are proposed.
基金supported by the National Research and Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology and Ministry of Knowledge Economy (Grant No. 2014045308)
文摘This study proposes a new electromagnetic rectangular mixer, and numerically examines the mixing characteristics of two different electrolyte solutions in the device under a uniform magnetic field. The mixer consists of a conduit with electrodes equipped on its top and bottom walls. The difference in the electric potentials applied to the sets of electrodes induces the current. The combination of the induced current and magnetic field yields Lorentz force, resulting in the fluid motion for pumping and mixing of the two different fluids. The numerical simulation is carried out with the use of commercial software CFX. The present numerical model is validated by an existing numerical work. The effect of different variables on mixing efficiency is investigated in many different cases with two different heights of the duct and various input voltages of the electrodes. The current simulation results indicate that the mixing performance can be enhanced by using multiple sets of electrodes and applying higher input voltages（absolute values） to the electrodes.
