Abstract
The vortex gripper is a non-contact suction device that uses a high-speed rotating airflow to create a negative pressure and suction force. In this research, we studied the effect of the vortex gripper’s diameter on the maximum suction force and internal flow field. First, we proposed a simplified theoretical model of the maximum suction force and predicted the influences of changing the diameter. Then, we obtained the maximum suction forces of the grippers with different diameters through the experiment. Both the theoretical and experimental results show that changing the diameter of the vortex gripper increases the maximum suction force. However, with the increase in the diameter, the prediction of the trend of the maximum suction force is inconsistent with the experimental results. To analyze the difference between the theoretical and experimental results, we further measured the pressure distribution of the vortex gripper and calculated the pressure gradient. The pressure distribution showed that the maximum negative pressure decreases while the diameter increases, and there is a pressure platform, which dominates the central area of the chamber. Next, we indirectly obtained the circumferential velocity distribution based on the relationship between the pressure gradient and circumferential velocity. The results of the circumferential velocity distribution reveal that the high-speed rotating airflow only exists in the area near the inner wall of the vortex chamber, while the circumferential velocity in the central part of the vortex chamber is extremely slow. In addition, the results clarify that the inaccurate assumption of velocity distribution of the simplified theoretical model is the main cause of the theoretical prediction bias.
Highlights
Rotating airflow has been utilized in some engineering apparatuses such as cyclone separators[1] which are used to separate fluid with different densities and heat exchangers[2,3,4] which are used to transfer heat between two fluids
Rotating airflow has been introduced as a method to generate suction force in a new pneumatic suction device called vortex gripper.[5]
The centrifugal force of the swirling airflow creates a negative pressure inside the vortex chamber, and the airflow exits through the clearance between the vortex gripper and sucked surface.[5]
Summary
Rotating airflow has been utilized in some engineering apparatuses such as cyclone separators[1] which are used to separate fluid with different densities and heat exchangers[2,3,4] which are used to transfer heat between two fluids. The vortex gripper has many important structural and usage parameters, for example, the diameters and number of tangential nozzles, shape and diameter of the vortex chamber, and supply condition. Based on these parameters, some of the works by the researchers is given as follows. The results showed that the other position settings were not as good as the tangential setting.[9,19] Zhao and Li15 investigated the effect of supply flow on the suction force and internal flow field and found that increasing the supply flow can enhance the maximum suction force and the suspension stiffness These efforts of optimized design research make the structure and the continuous use of the vortex gripper more reasonable.
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