Computational and Experimental Analysis of Axial Flow Cyclone Used for Intake Air Filtration in Internal Combustion Engines

The properties and advantages of axial flow cyclones are presented; several dozen of them are already widely used as the first stage of inlet air filtration in internal combustion motor vehicle engines, work machines and helicopters. The necessity to conduct research on cyclones to improve separation efficiency has been demonstrated. Using the commercial engineering software Ansys Fluent, at a constant inlet velocity of 10 m/s, an assessment was made on the effect of the separation length and inlet diameter of the outlet tube on changes in separation efficiency in axial flow cyclone. Each of the examined parameters was variable while maintaining other factors at a constant level. In the numerical calculations, test dust was used, which was the equivalent of AC fine dust, the particle size composition of which was taken into account using the Rosin–Rammler model. Increase in the separation efficiency was observed with an increase in the separation length and a decrease in the diameter of the cyclone inlet tube. For the cyclone model with an increased separation length and reduced diameter of the inlet pipe, numerical tests of separation efficiency and pressure drop were performed for various velocities at cyclone inlet in the range of 2.5–15 m/s. The obtained characteristics of modified axial flow cyclone were experimentally verified on a laboratory stand during cyclone prototype tests, the model of which was printed using the additive manufacturing technique.

Effects of roughness on the performance of axial flow cyclone separators using numerical simulation method

An axial flow cyclone is a separator with high efficiency and low resistance. Researchers have extensively studied the structure and parameters that have the greatest influence on its performance. However, the influence of wall roughness on the performance of axial flow cyclones has been neglected for a long time. The wall roughness height can be changed by the manufacturing process and the effect of particles on the wall. Thus, in this study, the effects of roughness on an axial flow cyclone are investigated using a numerical simulation method. The Reynolds stress model and discrete phase model are used for gas and particle prediction and the simulation result were verified through experimentation. The results of the numerical simulation show that the roughness height has big influence on axial flow cyclones. The separation efficiency decreases and static pressure drop increases with increasing roughness height. This happens especially at high inlet velocity. The tangential velocity decreases, particularly near the inner surface of the cyclone, and axial velocity increases in the center of the pipe. The trends show that the degree of change reduced for all parameters with increasing roughness height.

A CFD Method Study on the Resistance Performance of the Axial Flow Cyclone Separator

Axial flow cyclone separator with guide blade has been widely used, due to its low resistance, huge gas processing and small volume. Although its structure is simple, three-dimension strong rotating turbulent flow forms which involves many complex interactions such as dual-phase separation, adsorption and electrostatic interference. This paper is focused on studying the resistance performance of the axial flow cyclone separator. Numerical simulation methods are carried out to acquire the internal flow field characteristics under different operating pressure and temperature conditions. The result shows that the pressure drop decreases under the same operating pressure, as the operating temperature increases. When the operating temperature is the same, the higher operating pressure enhances the value of the pressure drop. Velocity distribution, pressure contours and turbulent viscosity contours have been presented, to analyze the characteristics of the internal airflow, so as to help optimize the design. Experiments are intended to verify the results of numerical simulation and explore the internal flow field of the cyclone separator further. The cyclone separator has 8 rotary blades which are split into 8 parts, namely one blade is 45° in the tangential direction. 0° and 22.5° are chosen in the experiment. The dimensionless pressure distribution is shown. A comparison of the CFD results and the experimental results is made to prove that the numerical simulation methods are correct and accurate. The curve of the numerical simulation results is very close to that of the experimental results with the similar trend. It is concluded that the methods can predict the internal flow field characteristics of the axial flow cyclone separator.