Papers by Keyword: Airflow Field

Abstract: This paper presents a numerical study to simulate airflow around an array of buildings with different heights. The simulation showed a complex 3D flow pattern around the buildings. The velocity and standard deviation around the short buildings increased by about 30% compared to the same arrangement with buildings of the same height. Thus, the existence of the tall buildings increased the turbulence level and velocity magnitude around the short buildings. This suggests that the proposed buildings arrangement and spacing were effective in improving the wind environment around the buildings.

Abstract: This study presents experiments conducted in an environmental wind tunnel using physical models to quantify the airflow field around array of buildings of two different heights. A complex airflow pattern was developed around the buildings. In addition, the tall buildings increased the turbulence level around the short buildings. Combining short and tall buildings increased the spatially averaged velocity and standard deviation around the short buildings by 25% compared to the velocity and standard deviation around buildings of the same height. Thus, the proposed buildings arrangement and spacing proved to be effective in improving the wind environment around the buildings.

Abstract: The blower is a kind of garden machinery, which blows strong wind to clean up leaves by a centrifugal fan, but it causes a loud aerodynamic noise. To compromise the contradiction between large air flow rate and low fan noise, some optimizations are proposed to reduce fan noise without lowering its air volume. In this paper, a CFD numerical model to compute airflow field of blower is established, where the centrifugal fan is simulated by the MRF model, and theturbulent model is selected. By smoothing the transition section, improving the volute tongue and optimizing the shape and optimizing number of fan blade, the blower work performance is increased obviously. In order to find out the actual working point, both the fan and motor load characteristic curves are drawn out. The simulation results show that, at the actual working point, the speed of the centrifugal fan is reduced, while the flow rate of blower is raised up. The optimizations are applied to the blower, and the experiment of the improved blower shows the flow rate is increased 5%, and the noise is reduced 2dB.

Abstract: Movement of large ship in waves is one of the important factors which can induce ship surface air turbulence; it is bound to a large impact on the air-flow field on deck, which affect the safety of the aircraft landing. In order to study the change of the flow field in the process of movement of large ship and its influence on aircrafts take-off and landing, under the same experimental condition of the unsteady condition. We set up 3d model, observe and analyze the ships air-flow field changes in the movement. Finally, calculate the results and give the effect of the aircraft landing in the key areas.

Abstract: Fiber air dispersion system (FADS) is a new flexible ventilation terminal in ventilated areas. It can be used in both air transmission and air diffusion. The cloth duct made of flame retardant polyester is critical. The conditioned air can be dispersed to environment by not only micro pores in the fabric but also slot and orifice on the fabric. The micro-pores in the fabric exist in the yarns and fibers. The laser can be used to cut the slot and orifice on the fabric. They can be designed based on the application. In this paper, air dispersion models and basic characteristics of fiber air dispersion system were introduced. Based on computational fluid mechanics theory, the flame retardant cloth ducts (FRCD) is regard as an isotropic porous media. The air dispersion physical model for micro porous that sends the air to the environment was established. And the Carman-kozeny equation was used in this model, which was described the airflow field in the FRCD. Finally the airflow field in the FRCD was numerically simulated with the FLUENT software based on the finite element method. The air flow resistance of the fabrics was calculated by the Darcy model.

Abstract: In order to study the impact of the different structures in the air-suction seed metering device of no-tillage planter on seeding performance, based on the structural characteristics of vacuum chamber in air-suction seed metering device of no-tillage planter, the air flow finite element analysis of air-suction seed metering device and experimental verification were did. Mainly the law of the distribution of airflow field and seeding performance of the vacuum chamber under the situation of the different distribution diameters of the suction hole were studied in this paper. The result shows that the adsorption performance is best when the suction hole distribution diameter is 150 mm. The conclusion can provide a reference for structural optimization and performance improvement of the air-suction seed metering device of no-tillage planter.

Abstract: Controlling the concentration of contaminants in wards to prevent airborne infection is an important issue in hospital. The effect of supply airflow of down-feed air curtain, which locates between patients and doctors/nurses, is to separate wards into two spaces, one for patients and the other for doctors/nurses. The controlling effects of air curtain on contaminants emitted by patients are numerically simulated under different air arrangements. In a laboratory model, the smoke of burning Zang incense serves as the source of contaminants. Particles’ concentration of contaminants was tested with a laser particle counter at different sites whether the air curtain was running or not. Draughty feel on patients caused by supply airflow of air curtain was researched in this study. Results of the present study revealed that air curtain could control contaminants effectively, and the supply airflow did not make patients discomfort basically. Finally, the appropriate air outlet location and distance between air curtain and patients were suggested.

Abstract: It is necessary to supply enough grinding fluid during grinding process to lower grinding temperature. But, there is little grinding fluid into the contact area actually due to the airflow layer with high pressure around grinding wheel. In this paper, the finite element analysis and simulation on airflow field in the grinding zone is performed based on hydrodynamics. The performance and the influencing mechanism of the airflow field on effective grinding fluid are analyzed further. The research works show that it is important to design the grinding wheel and fluid jet parameters reasonably for increasing the proportion of effective grinding fluid.

Abstract: Adopting the method of PIV, systematical theory analysis and experiment research were made on the airflow field distribution of super-high speed pectination grinding wheel, as well as experiment design and data acquisition, the data processing was carried out through the software of FlowMap, Tecplot, and Matlab. By analysis and discussion focused on experiment results, the general rules of airflow field distribution in super-high speed pectination grinding wheel were preliminary drawn, which provides the research foundation with a view to find a new method for the effective supply of super-high speed grinding coolant.

Abstract: The investigation of the experiment method on airflow field around super-high grinding wheel by PIV (Particle Image of Velocity, PIV) instrument was introduced in the paper. The measure system and scheme were designed for the experiment with PIV applied in the super-high speed grinding wheel for the airflow. The processing method of experimental data was discussed and the experiment result validated the feasibility of the experiment method.