Theoretical and Experimental Study and Design Method of Blade Height of a Rotational-Flow Suction Unit in a Wall-Climbing Robot

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Ningning Chen ◽  
Kaige Shi ◽  
Xin Li
Keyword(s):  
High Speed ◽  
Design Method ◽  
Rotational Flow ◽  
Climbing Robot ◽  
Suction Force ◽  
Blade Height ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Motor Operation ◽  
The Relationship

Abstract A wall-climbing robot that uses a rotational-flow suction unit to be non-contact-absorbed onto walls can climb rough walls and overstep obstacles. In the rotational-flow suction unit, the air driven by the blades rotates at a high speed within a chamber, thereby creating and maintaining a negative pressure distribution. This study is focused on the modeling and design of the blade height. First, a theoretical model of the rotation flow, containing two important parameters (i.e., blade height Hb and clearance h), was established and verified experimentally. Furthermore, the computational fluid dynamics (CFD) method was applied to illustrate the secondary flow relative to the blades, revealing that it gives rise to a nonlinear velocity distribution. It was found that an increase in the blade height greatly improves the F–h characteristics; in addition, the relationship between the power consumption and suction force (E˙−F curve) is mainly determined by the clearance h instead of the blade height Hb. Based on these findings, we propose a design method for determining the suitable blade height. According to the characteristic load curves of the suction units (i.e., the T–ω curves) and the motor characteristics, suitable blades can be selected to match the motor operation (i.e., nominal operating state).

Aerodynamic Loading Induced by Muzzle Flows on Small Caliber Spin Stabilized Projectiles

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Chuanlin Chen ◽  
Hui Xu ◽  
Chenlei Huang ◽  
Zhongxin Li ◽  
Zhilin Wu
Keyword(s):  
High Speed ◽  
Exponential Relationship ◽  
Interior Ballistics ◽  
Aerodynamic Loading ◽  
Axial Forces ◽  
Pitch Moment ◽  
Temporal Pressure ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Element Method

Abstract In this study, we examined the aerodynamic loading on a small caliber rifle (spin stabilized) projectile moving in a muzzle flow field using an element method to analyze the loading and the effect of the angle of attack (for small angles from 0 to 3 deg) on the different components. The temporal pressure distribution on the projectile, which forms the basis of the element method, was computed using a computational fluid dynamics (CFD) analysis combined with a classical interior ballistics model. Then, a high-speed optical experiment was conducted to verify the results of the CFD method and ensure the accuracy of the calculations. The results were as follows: (a) similar to a large caliber projectile, the total axial force, which consisted primarily of the axial forces on the base and boattail, was found to have an inverse exponential relationship with time; (b) the overall lift was a combination of the lift of the base, boattail, cylinder, and nose; and (c) the interaction between the pitch moment of the base and that of the boattail was found to be the primary contributing factor to the total pitch moment. Based on these results, we recommend that the characteristics of the base and boattail be considered when specifying the geometric configuration of a projectile.

scholarly journals Numerical Analysis on the Hydrodynamic Performance of an Artificially Ventilated Surface-Piercing Propeller

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1499 ◽  
Author(s):  
Dongmei Yang ◽  
Zhen Ren ◽  
Zhiqun Guo ◽  
Zeyang Gao
Keyword(s):  
High Speed ◽  
Artificial Ventilation ◽  
Water Immersion ◽  
Numerical Results ◽  
Hydrodynamic Performance ◽  
Heavy Load ◽  
Computational Fluid Dynamics Cfd ◽  
Large Water ◽  
Cfd Method ◽  
Surface Piercing Propeller

When operated under large water immersion, surface piercing propellers are prone to be in heavy load conditions. To improve the hydrodynamic performance of the surface piercing propellers, engineers usually artificially ventilate the blades by equipping a vent pipe in front of the propeller disc. In this paper, the influence of artificial ventilation on the hydrodynamic performance of surface piercing propellers under full immersion conditions was investigated using the Computational Fluid Dynamics (CFD) method. The numerical results suggest that the effect of artificial ventilation on the pressure distribution on the blades decreases along the radial direction. And at low advancing speed, the thrust, torque as well as the efficiency of the propeller are smaller than those without ventilation. However, with the increase of the advancing speed, the efficiency of the propeller rapidly increases and can be greater than the without-ventilation case. The numerical results demonstrates the effectiveness of the artificial ventilation approach for improving the hydrodynamic performance of the surface piercing propellers for high speed planning crafts.

Computational aeroelastic analysis of slowed rotors at high advance ratios

2014 ◽  
Vol 118 (1201) ◽  
pp. 297-313 ◽  
Author(s):  
J. de Montaudouin ◽  
N. Reveles ◽  
M. J. Smith
Keyword(s):  
High Speed ◽  
Rotor Blades ◽  
Vortex Interaction ◽  
Blade Loading ◽  
Blade Vortex Interaction ◽  
Aeroelastic Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Advance Ratio ◽  
Cfd Method ◽  
Model Rotor

Abstract The aerodynamic and aeroelastic behaviour of a rotor become more complex as advance ratios increase to achieve high-speed forward fight. As the rotor blades encounter large regions of cross and reverse flows during each revolution, strong variations in the local Mach regime are encountered, inducing complex elastic blade deformations. In addition, the wake system may remain in the vicinity of the rotor, adding complexity to the blade loading. The aeroelastic behaviour of a model rotor with advance ratios ranging from 0·5 to 2·0 has been evaluated with aerodynamics provided via a computational fluid dynamics (CFD) method. Significant radial blade-vortex interaction can occur at a high advance ratio; the advance ratio at which this occurs is dependent on the rotor configuration. This condition is accompanied by high vibratory loads, peak negative torsion, and peak torsion and in-plane loads. The high vibratory loading increases the sensitivity of the trim model, so that at some high advance ratios the vibratory loads must be filtered to achieve a trimmed state.

Analysis and Simulation of Inner Flow Condition of a Novel Rotary on/off Valve

2012 ◽  
Vol 220-223 ◽  
pp. 1698-1702
Author(s):  
Jian Chen ◽  
Zhu Ming Su ◽  
Qi Zhou ◽  
Jian Ping Shu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Condition ◽  
High Speed ◽  
Ansys Fluent ◽  
Revolution Speed ◽  
Pressure Profiles ◽  
Open Case ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

A novel hydraulic rotary high speed on/off valve is investigated. The function of the outlet turbine and the effect on revolution speed of valve spool are analyzed. The inner fluid flow condition under full open case of the on/off valve is simulated using computational fluid dynamics(CFD) method based on Ansys/Fluent and velocity and pressure profiles of fluid inside valve are obtained. Suggestions on optimizing the geometry of valve to decrease transition losses are given.

scholarly journals Research on Ship Hull Optimisation of High-Speed Ship Based on Viscous Flow/Potential Flow Theory

2020 ◽  
Vol 27 (1) ◽  
pp. 18-28
Author(s):  
Zhang Baoji
Keyword(s):  
High Speed ◽  
Design Method ◽  
Frictional Resistance ◽  
Linear Wave ◽  
Total Resistance ◽  
Friction Resistance ◽  
Resistance Reduction ◽  
Before And After ◽  
Reduction Effect ◽  
Cfd Method

AbstractIn order to quickly obtain practical ship forms with good resistance performance, based on the linear wave-making resistance theory, the optimal design method of ship forms with minimum total resistance is discussed by using the non-linear programming (NLP) method. Taking the total resistance as the objective function (the Michell integral is used to calculate the wave-making resistance and the equivalent plate friction resistance formula is used to calculate the frictional resistance), the hull surface offset as the design variable and appropriate displacement as the basic constraints, and considering the additional constraints, the hull bow shape and the whole ship are optimised, and an improved hull form is obtained. The resistance of the ship before and after optimisation is calculated by the CFD method to further evaluate the resistance reduction effect and performance after optimisation. Finally, an example of optimisation calculation of an actual high-speed ship is given. The obvious resistance reduction results confirm the reliability of the optimisation design method.

scholarly journals Minimization of the Energy Consumption in Industrial Robots through Regenerative Drives and Optimally Designed Compliant Elements

2020 ◽  
Vol 10 (21) ◽  
pp. 7475
Author(s):  
Ilaria Palomba ◽  
Erich Wehrle ◽  
Giovanni Carabin ◽  
Renato Vidoni
Keyword(s):  
Energy Consumption ◽  
High Speed ◽  
Design Method ◽  
Electrical Energy ◽  
Motor Drives ◽  
Industrial Robots ◽  
Test Cases ◽  
Electrically Actuated ◽  
System Energy ◽  
The Relationship

This paper describes a method for reducing the energy consumption of industrial robots and electrically actuated mechanisms performing cyclic tasks. The energy required by the system is reduced by outfitting it with additional devices able to store and recuperate energy, namely, compliant elements coupled in parallel with axles and regenerative motor drives. Starting from the electromechanical model of the modified system moving following a predefined periodic path, the relationship between the electrical energy and the stiffness and preload of the compliant elements is analyzed. The conditions for the compliant elements to be optimal are analytically derived. It is demonstrated that under these conditions the compliant elements are always beneficial for reducing the energy consumption. The effectiveness of the design method is verified by applying it to two test cases: a five-bar mechanism and a SCARA robot. The numerical validations show that the system energy consumption can be reduced up to the 77.8% while performing a high-speed, standard, not-optimized trajectory.

Comparative Investigation of an Automated Oceanic Wave Surface Glider Robot Influence on Resistance Prediction Using CFD Method

2015 ◽  
Vol 710 ◽  
pp. 91-97
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng
Keyword(s):  
High Speed ◽  
Water Resistance ◽  
Comparative Investigation ◽  
Numerical Predictions ◽  
Calm Water ◽  
Oceanic Wave ◽  
Computational Fluid Dynamics Cfd ◽  
Wave Glider ◽  
Cfd Method ◽  
Solution Parameters

Thewave glideris composed of two parts: the float is roughly the size and shape of a surfboard that contains all the instrumentation needed for scientific experiments; the sub has wings and hangs 6 meters below on an umbilical tether. This difference allows wave energy to be harvested to produce forward thrust. According to the lake of design information and data for thewave glider, the main aim of the study is usingcomputational fluid dynamics (CFD)to present a method to predict calm water resistance for the floating part of thewave glider(the hull).Wigley parabolic hulland high speed round bilge form (NPL)have been investigated in order to estimate the hydrodynamic performances of the hull usingCFDsoftware fluent.Wave glideris designed with slender hull shapes in order to decrease the wave making resistance of the ship.In this paper a method is evaluated by comparing the numerical predictions forwigleyandNPLforms (2m) using the same mesh generation method under the same conditions to design the hull. Calculations fortotal calm water resistanceare carried out using three different mesh sizes for Froude numbers in the range of 0.10 to 0.40 and compared for accuracy of the solution parameters. The close agreement between the numerical predictions shows the importance ofCFDapplications in estimating the hydrodynamics performance to design the floating hull and the numerical method is useful in glider design. This means that the method discussed in this paper can be used for the resistance calculation of some hulls like the float of the glider.

Numerical Analysis of a Centrifugal Fan for a Road Sweeper

2017 ◽  
Author(s):  
Xiaoxuan Chen ◽  
Mingyang Yang ◽  
Kangyao Deng ◽  
Yunlong Bai
Keyword(s):  
Flow Field ◽  
Field Analysis ◽  
Centrifugal Fan ◽  
Suction Force ◽  
Flow Loss ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Field Analysis ◽  
Cfd Method ◽  
Original Configuration ◽  
Inlet Duct

Road sweeper is the widely-employed machine to clear up garbage and dust on streets. Its performance has profound influence on the reduction of fuel consumption and hence CO2 emission. The key component of a road sweeper is a centrifugal fan which produces suction force for clearing. Therefore, the performance of this device has direct impact on fuel economy of the machine. This paper targets at the performance analysis of a centrifugal fan in a commercial road sweeper. Firstly, the performance and flow field of the centrifugal fan are analyzed by computational fluid dynamics (CFD) method. The breakdown of the flow loss in the fan shows that the volute and the impeller are major components contributing to flow loss in the fan. The flow at the inlet of the impeller is highly distorted due the interaction among the asymmetrical inlet duct, the leakage and the volute tongue. Because of the interaction, flow passages near the tongue are the ones with the highest flow loss. Moreover, the flow velocity entering the volute is considerably high which thus results in high flow loss in the volute. Finally, based on the flow field analysis, an inlet duct with round shape is designed preliminarily and simulated together with the centrifugal fan. The results show that the efficiency can be improved by more than 4% compared with the original configuration due to the alleviation of the interaction.

scholarly journals Numerical and Experimental Study on Seakeeping Performance of a High-Speed Trimaran with T-foil in Head Waves

2019 ◽  
Vol 26 (3) ◽  
pp. 65-77 ◽  
Author(s):  
Ang Li ◽  
Yunbo Li
Keyword(s):  
High Speed ◽  
Experimental Tests ◽  
Longitudinal Motion ◽  
Vertical Acceleration ◽  
Large Wave ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Computational Fluid Dynamics Cfd ◽  
Motion Characteristics ◽  
Cfd Method

Abstract The longitudinal motion characteristics of a slender trimaran equipped with and without a T-foil near the bow are investigated by experimental and numerical methods. Computational fluid dynamics ( CFD) method is used in this study. The seakeeping characteristics such as heave, pitch and vertical acceleration in head regular waves are analyzed in various wave conditions. Numerical simulations have been validated by comparisons with experimental tests. The influence of large wave amplitudes and size of T-foil on the longitudinal motion of trimaran are analyzed. The present systematic study demonstrates that the numerical results are in a reasonable agreement with the experimental data. The research implied that the longitudinal motion response values are greatly reduced with the use of T-foil.

The Modified Temperature Field of Ceramic Roller Kiln Based on DEPSO Algorithm

2011 ◽  
Vol 219-220 ◽  
pp. 1423-1426
Author(s):  
He Huang ◽  
Xi Shen Chen ◽  
Hong Lei ◽  
Zhuo Qiu Li ◽  
Wu Gang Li
Keyword(s):  
Fluid Dynamics ◽  
Temperature Field ◽  
High Speed ◽  
Model Building ◽  
Roller Kiln ◽  
Ceramic Roller ◽  
Field Uniformity ◽  
Kiln Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
The Relationship

The relationship between ceramic roller kiln simulation model building parameters and temperature field uniformity is extremely difficult work. In this paper, DEPSO-CFD, a system integrated of an algorithm of hybrid particle swarm (PSO) with Differential Evolution (DE) operator, termed DEPSO, and computational fluid dynamics (CFD), is proposed to meet the demand. And with the help of the efficient parallel calculation, the ceramic roller kiln temperature field uniformity is mainly researched by using Fluent and DEPSO algorithm. It proves that the system is of high speed and of excellent parameter exploration capability, and the final computational example is got; thus parallel-DEPSO-CFD is of great academic value and significant applicable value.

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