Two-dimensional pressure field and backflow in the annular skirt of vortex gripper

2020 ◽  
pp. 095440622097404
Author(s):  
Jianghong Zhao ◽  
Xin Li
Keyword(s):  
Flow Field ◽  
Pressure Distribution ◽  
Local Stress ◽  
Vortex Chamber ◽  
Physical Contact ◽  
Two Dimensional ◽  
Stress Concentrations ◽  
Suction Force ◽  
Maximum Value ◽  
Gap Height

The vortex gripper is a kind of pneumatic noncontact gripper that does not produce a magnetic field and heat. It can grip a workpiece without physical contact, which avoids any unintentional damage such as mechanical scratches, local stress concentrations, frictional static electricity, and surface stains. This study focused on the two-dimensional pressure distribution field on a workpiece surface under the vortex gripper. Theoretical, experimental, and computational fluid dynamics results were combined to study the backflow phenomenon in the annular skirt, which can decrease the gripper’s suction force after the maximum value is reached. First, the pressure distribution in the annular skirt was theoretically modeled. A comparison with the experimental results showed that increasing the gap height between the gripper and workpiece generates a circumferentially asymmetrical flow field in the skirt. Based on this, it was hypothesized that an airflow in the circumferential direction may exist. The experimental data and simulation results were analyzed under large gap height conditions to observe the backflow in detail and it was found that an uneven pressure distribution with positive and negative pressure regions generated by the uneven flow is the root cause of the backflow. Finally, the effect of the backflow on the flow field in two different flow regions (in the annular skirt and inside the vortex chamber) was analyzed and the reason why the suction force of the vortex gripper has a maximum value was determined.

Generalization of Experimental Data for Compressor Cascades at Low Speeds

1970 ◽  
Author(s):  
V. S. Beknev
Keyword(s):  
Experimental Data ◽  
Pressure Distribution ◽  
Loss Coefficient ◽  
Two Dimensional ◽  
Minimum Loss ◽  
Maximum Value ◽  
Isentropic Exponent ◽  
Loss Coefficients ◽  
Low Speeds ◽  
Drag Ratio

The author compares three different approaches for generalization of experimental data for two-dimensional compressor cascades at low speeds: generalization for maximum value of lift-drag ratio, generalization for maximum cascade quality, and generalization for minimum loss coefficient. Some results given, of comparison for incidence and deviation angles, solidities, and loss coefficients, show the largest difference to be for incidence angles and loss coefficients. Influence of isentropic exponent on the airfoil pressure distribution and cascade losses is considered.

Boundary-Layer Explorations Over a Two-Dimensional Mast/Sail Geometry

1990 ◽  
Vol 27 (04) ◽  
pp. 250-256
Author(s):  
Stuart Wilkinson
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Pressure Distribution ◽  
Skin Friction ◽  
Static Pressure ◽  
Separated Flow ◽  
Velocity Profiles ◽  
Two Dimensional ◽  
Representative Data ◽  
Static Pressure Distribution

An experimental aerodynamic boundary-layer investigation is performed over the suction surfaces of a typical two-dimensional mast/sail geometry. Velocity profiles are obtained at a number of locations which, together with visualization data and the corresponding static pressure distribution, are used to describe the fundamental nature of the complex partially separated flow field associated with such geometries. The velocity profiles are fully analyzed to provide thickness parameters and skin friction coefficients, suitable for use as representative data in the development of predictive theories involving viscid-inviscid interactions. The chordwise variations of the thickness parameters are graphically presented and discussed.

Heat Transfer Measurements Downstream of a Two-Dimensional Jet Entering a Crossflow

1987 ◽  
Vol 109 (4) ◽  
pp. 572-578 ◽  
Author(s):  
S. Wittig ◽  
V. Scherer
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Pressure Distribution ◽  
Momentum Flux ◽  
Static Pressure ◽  
Flux Ratio ◽  
Main Flow ◽  
Two Dimensional ◽  
Reattachment Point ◽  
Static Pressure Distribution

Nusselt and Stanton numbers have been evaluated in and behind the recirculating zone produced by a two-dimensional jet entering a crossflow. The momentum flux ratio of the jet to the main flow was varied from 1.44–8.4 and measurements of the static pressure distribution and of the flow field by a five-hole probe were performed. A relation between the location of the reattachment point of the flow and the maximum of heat transfer was observed. Comparisons with available data are made. The experiments are intended for the verification of calculational codes.

The Measurement of Boundary Layers on a Compressor Blade in Cascade: Part 1—A Unique Experimental Facility

1987 ◽  
Vol 109 (4) ◽  
pp. 520-526 ◽  
Author(s):  
S. Deutsch ◽  
W. C. Zierke
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Pressure Distribution ◽  
Static Pressure ◽  
Compressor Blade ◽  
Boundary Layer Transition ◽  
Two Dimensional ◽  
Suction Surface ◽  
Pressure Surface ◽  
Static Pressure Distribution

A unique cascade facility is described which permits the use of laser-Doppler velocimetry (LDV) to measure blade boundary layer profiles. Because of the need for a laser access window, the facility cannot reply on continuous blade pack suction to achieve two-dimensional, periodic flow. Instead, a strong suction upstream of the blade pack is used in combination with tailboards to control the flow field. The distribution of the upstream suction is controlled through a complex baffling system. A periodic, two–dimensional flow field is achieved at a chord Reynolds number of 500,000 and an incidence angle of 5 deg on a highly loaded, double circular arc, compressor blade. Inlet and outlet flow profiles, taken using five-hole probes, and the blade static-pressure distribution are used to document the flow field for use with the LDV measurements (see Parts 2 and 3). Inlet turbulence intensity is measured, using a hot wire, to be 0.18 percent. The static-pressure distribution suggests both separated flow near the trailing edge of the suction surface and an initially laminar boundary layer profile near the leading edge of the pressure surface. Probe measurements are supplemented by sublimation surface visualization studies. The sublimation studies place boundary layer transition at 64.2 ± 3.9 percent chord on the pressure surface, and indicate separation on the suction surface at 65.6 percent ± 3.5 percent chord.

scholarly journals Effect of chamber diameter of vortex gripper on maximum suction force and flow field

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983740 ◽  
Author(s):  
Ching Wang ◽  
Jianghong Zhao ◽  
Xin Li
Keyword(s):  
Theoretical Model ◽  
Flow Field ◽  
Pressure Gradient ◽  
Velocity Distribution ◽  
Negative Pressure ◽  
High Speed ◽  
Vortex Chamber ◽  
Experimental Results ◽  
Circumferential Velocity ◽  
Suction Force

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.

Evaluation of Pressure Distribution on a Cavitating Hydrofoil With Flap

1967 ◽  
Vol 11 (02) ◽  
pp. 93-108
Author(s):  
Z. L. Harrison ◽  
Duen-pao Wang
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Flow Model ◽  
Wake Flow ◽  
Two Dimensional ◽  
The Moment ◽  
Cavitating Hydrofoil ◽  
General Method

A general method is established to calculate the pressure distribution and the moment of force for a two-dimensional, supercavitating hydrofoil with a flap. The wake flow model is adopted to describe the configuration of the flow field. Some numerical results for a supercavitating flat plate with a flap are compared with the corresponding experimental data.

scholarly journals Influence of a Standing Wave Flow-Field on the Dynamics of a Spray Diffusion Flame

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 27
Author(s):  
J. Barry Greenberg ◽  
David Katoshevski
Keyword(s):  
Liquid Phase ◽  
Flow Field ◽  
Standing Wave ◽  
Diffusion Flame ◽  
Stokes Number ◽  
Flame Height ◽  
Wave Flow ◽  
Two Dimensional ◽  
Governing Equations ◽  
First Time

A theoretical investigation of the influence of a standing wave flow-field on the dynamics of a laminar two-dimensional spray diffusion flame is presented for the first time. The mathematical analysis permits mild slip between the droplets and their host surroundings. For the liquid phase, the use of a small Stokes number as the perturbation parameater enables a solution of the governing equations to be developed. Influence of the standing wave flow-field on droplet grouping is described by a specially constructed modification of the vaporization Damkohler number. Instantaneous flame front shapes are found via a solution for the usual Schwab–Zeldovitch parameter. Numerical results obtained from the analytical solution uncover the strong bearing that droplet grouping, induced by the standing wave flow-field, can have on flame height, shape, and type (over- or under-ventilated) and on the existence of multiple flame fronts.

scholarly journals Two-dimensional flow field distribution characteristics of flocking drainage pipes in tunnel

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 139-148
Author(s):  
Shiyang Liu ◽  
Xuefu Zhang ◽  
Feng Gao ◽  
Liangwen Wei ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Flow Field ◽  
Field Distribution ◽  
Rapid Development ◽  
Maximum Velocity ◽  
Distribution Characteristics ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Laboratory Test Results ◽  
Transverse Distance ◽  
Two Dimensional Flow

AbstractWith the rapid development of traffic infrastructure in China, the problem of crystal plugging of tunnel drainage pipes becomes increasingly salient. In order to build a mechanism that is resilient to the crystal plugging of flocking drainage pipes, the present study used the numerical simulation to analyze the two-dimensional flow field distribution characteristics of flocking drainage pipes under different flocking spacings. Then, the results were compared with the laboratory test results. According to the results, the maximum velocity distribution in the flow field of flocking drainage pipes is closely related to the transverse distance h of the fluff, while the longitudinal distance h of the fluff causes little effect; when the transverse distance h of the fluff is less than 6.25D (D refers to the diameter of the fluff), the velocity between the adjacent transverse fluffs will be increased by more than 10%. Moreover, the velocity of the upstream and downstream fluffs will be decreased by 90% compared with that of the inlet; the crystal distribution can be more obvious in the place with larger velocity while it is less at the lower flow rate. The results can provide theoretical support for building a mechanism to deal with and remove the crystallization of flocking drainage pipes.

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