scholarly journals Numerical simulation and optimization of aerodynamic uplift force of a high-speed pantograph

2021 ◽  
Author(s):  
Zhiyuan Dai ◽  
Tian Li ◽  
Ning Zhou ◽  
Jiye Zhang ◽  
Weihua Zhang
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Lift Force ◽  
Wind Tunnel Test ◽  
Simulation Method ◽  
Operating Conditions ◽  
Contact Forces ◽  
Simulation And Optimization ◽  
Uplift Force ◽  
Uplift Forces

AbstractAiming at the problem that aerodynamic uplift forces of the pantograph running in the knuckle-downstream and knuckle-upstream conditions are inconsistent, and their magnitudes do not satisfy the corresponding standard, the aerodynamic uplift forces of pantographs with baffles are numerically investigated, and an optimization method to determine the baffle angle is proposed. First, the error between the aerodynamic resistances of the pantograph obtained by numerical simulation and wind tunnel test is less than 5%, which indicates the accuracy of the numerical simulation method. Second, the original pantograph and pantographs equipped with three different baffles are numerically simulated to obtain the aerodynamic forces and moments of the pantograph components. Three different angles for the baffles are −17°, 0° and 17°. Then the multibody simulation is used to calculate the aerodynamic uplift force of the pantograph, and the optimal range for the baffle angle is determined. Results show that the lift force of the baffle increases with the increment of the angle in the knuckle-downstream condition, whereas the lift force of the baffle decreases with the increment of the angle in the knuckle-upstream condition. According to the results of the aerodynamic uplift force, the optimal angle of the baffle is determined to be 4.75° when the running speed is 350 km/h, and pantograph–catenary contact forces are 128.89 N and 129.15 N under the knuckle-downstream and knuckle-upstream operating conditions, respectively, which are almost equal and both meet the requirements of the standard EN50367:2012.

scholarly journals Numerical Simulation for Engine/Airframe Interaction Effects of the BWB300 on Aerodynamic Performances

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Gang Yu ◽  
Dong Li ◽  
Yue Shu ◽  
Zeyu Zhang
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Separated Flow ◽  
Simulation Method ◽  
Interaction Effects ◽  
Surface Flow ◽  
Concept Design ◽  
Aerodynamic Forces ◽  
Low Speed ◽  
Aerodynamic Performances

The engine/airframe interaction effects of the BWB300 on aerodynamic performances were analyzed by using the numerical simulation method. The BWB300 is a 300-seat Blended Wing Body airplane designed by the Airplane Concept Design Institute of Northwestern Polytechnical University. The engine model used for simulation was simplified as a powered nacelle. The results indicated the following: at high speed, although the engine/airframe interaction effects on the aerodynamic forces were not significant, the airframe’s upper surface flow was greatly changed; at low speed, the airframe’s aerodynamic forces (of the airplane with/without the engine) were greatly different, especially at high attack angles, i.e., the effect of the engine suction caused the engine configuration aerodynamic forces of the airframe to be bigger than those without the engine; and the engine’s installation resulting in the different development of flow separation at the airframe’s upper surface caused greater obvious differences between the 2 configurations at high angles and low speed. Moreover, at low-speed high attack angles, the separated flow from the blended area caused serious distortion at the fan inlet of the engine.

Experiment and Numerical Simulation of Extrudate Swell in the Polymer Extrusion Process

2011 ◽  
Vol 314-316 ◽  
pp. 401-404 ◽  
Author(s):  
Min Zhang ◽  
Chuan Zhen Huang ◽  
Guo Wen Chen ◽  
Yu Xi Jia
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Three Dimensional ◽  
Simulation Method ◽  
Extrusion Process ◽  
High Speed Photography ◽  
The Finite Element Method ◽  
Polymer Extrusion ◽  
Extrudate Swell ◽  
Rate Profile

The extrudate swell of the polymer extrusion process was studied with the experiment and simulation method. The extrudate swell process was recorded by the high-speed photography apparatus. The swell rate at the different time was calculated. It is found that the extrudate swell rate increase at the first five seconds. The maximum swell rate is about 4.37%. The three-dimensional numerical simulation model of the experiment die path was founded. The extrusion process including the extrudate swell was simulated used the Finite Element Method. Such simulated results as the velocity vector, the shear rate profile and the end of the swell zone were analyzed. The extrudate swell end got by the simulation is similar with the experiment result.

Aerodynamic Heating Numerical Simulation of Terminal-Sensitive Projectile at Deceleration and Despinning Trajectory

2013 ◽  
Vol 376 ◽  
pp. 317-322
Author(s):  
Jun Zhang ◽  
Rong Zhong Liu ◽  
Rui Guo ◽  
Xiao Dong Ma
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Thermal Protection ◽  
Thermal Characteristics ◽  
Simulation Method ◽  
Aerodynamic Heating ◽  
Transient Temperature ◽  
Physical Parameters ◽  
Temperature Distributions ◽  
Infrared Signature

Aero-heating problem severely affects the performance of terminal-sensitive projectile (TSP) when projected out of the carrier capsule by the gunpowder gas at a high speed. In this paper, based on the typical ballistic data and airflow physical parameters at deceleration and despinning trajectory, the aerodynamic thermal characteristics of a TSP was simulated by Fluent, and the transient temperature distributions were obtained under the different flying conditions. Finally, we got stagnation temperatures by the numerical simulations which were similar to those by the engineering evaluation, and demonstrate the effectiveness of the simulation method. The results are valuable to the research of thermal protection and infrared signature of TSP.

Lubrication and Thermal Failure Mechanism Analysis in High-Speed Angular Contact Ball Bearing

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Wang Yunlong ◽  
Wang Wenzhong ◽  
Li Yulong ◽  
Zhao Ziqiang
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Ball Bearing ◽  
Rolling Bearing ◽  
Operating Conditions ◽  
Contact Forces ◽  
Mechanism Analysis ◽  
Angular Contact Ball Bearing ◽  
Thermal Failure ◽  
Lubrication Performance

Lubrication analysis of rolling bearing is often conducted with assumed operating conditions, which does not consider the effect of internal dynamics of rolling bearing. In this paper, the effects of the applied load and bearing rotational speed on the lubrication performance in an angular contact ball bearing are conducted, which combines the bearing dynamic analysis and thermo-elastohydrodynamic lubrication (TEHL) analysis. First, the internal motions and contact forces are obtained from the developed bearing dynamic model, and then were integrated into the TEHL model to investigate the lubrication performance of the bearing. The results show that the rotational speed and external load has significant effects on film thickness, temperature, and power loss; if the improper axial load is applied for certain bearing speed, the lubrication performance will deteriorate and thermal failure may occur; there exists critical load or speed to keep good lubrication performance and avoid thermal failure; the skidding contributes to the thermal failure and bad lubrication performance.

The Aerodynamic Analysis for Iced Four Bundled Transmission Lines with Typical Crescent

2014 ◽  
Vol 8 (1) ◽  
pp. 84-89 ◽  
Author(s):  
Liu Yuejun ◽  
Tang Ai P. ◽  
Liu Ke T. ◽  
Tu Jie W.
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Transmission Lines ◽  
Angle Of Attack ◽  
Wind Tunnel Test ◽  
Simulation Method ◽  
Single Wire ◽  
Wind Tunnel Tests ◽  
Absolute Value ◽  
Aerodynamic Test

Despite the fact that the wind tunnel tests have been carried out on iced transmission lines subjected to wind load, it is not practical to do wind tunnel tests due to its high cost. This paper describes a detailed numerical simulation method that can be used to instead of wind tunnel tests. Based on the galloping mechanism of iced transmission lines, the aerodynamic test was simulated with the typical crescent super-large thickness iced four bundled conductors. One of the results highlighted in this study is that the wind angle of attack had significant influence on the aerodynamics of iced conductors. The Den-Hartog and O.Nigol coefficient were calculated to determine galloping of iced transmission lines, comparing with the reference of wind tunnel test in the Zhejiang university, the range of the wind angle of attack to the bundled conductor which can lead to gallop is larger than single wire, but the absolute value of amplitude is less than the single conductor, split conductor is more likely to gallop than single conductor.

Research on Numerical Simulation of Heliostat's Surface Wind Pressure

2012 ◽  
Vol 517 ◽  
pp. 809-816 ◽  
Author(s):  
Ying Ge Wang ◽  
Zheng Nong Li
Keyword(s):  
Numerical Simulation ◽  
Surface Wind ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Operating Conditions ◽  
Wind Pressure ◽  
Wind Resistance ◽  
Pressure Distributions ◽  
Complex Projects ◽  
Simulation Based

Heliostat is the major part of solar tower power station whose wind resistance is deemed significant in design. The CFD model of single heliostat under typical operating situation was founded by technology of numerical simulation based on standard k-ε model. This paper puts forward a mesh generation method applied to complex projects under different working conditions. The corresponding UDF program was framed & used to simulate proper wind field entry conditions. The wind pressure distributions variation rules at different wind direction & elevation angles got summarized. The drag coefficients, the lift coefficients, and the three-dimensional moment coefficients in wind power coordinate under different operating conditions were computed. The results agree well with experimental data though a little bigger error exists locally. Moreover, the flow field distribution hard to acquire in wind tunnel test was compensated to further explain origin of heliostats wind pressure distribution. The influencing factors and the variation rules discovered reveals that prediction by numerical simulation is practically satisfactory.

Numerical Simulation of Dynamic Response of Planing Craft Sailing in Calm Water

2014 ◽  
Vol 590 ◽  
pp. 37-41
Author(s):  
Yu Min Su ◽  
Yun Hui Li ◽  
Hai Long Shen
Keyword(s):  
Numerical Simulation ◽  
Empirical Formula ◽  
High Speed ◽  
Evaluation Method ◽  
Simulation Method ◽  
Experimental Results ◽  
Planing Craft ◽  
Calm Water ◽  
Performance Evaluation Method ◽  
Good Agreement

In order to forecast the sailing response of planing craft at high speed rapidly and accurately, CFD code Fine/Marine solver was used to calculate the resistance and sailing attitude of a high-speed planing craft, then the numerical results were compared with experimental results and empirical formula results. The results showed that resistance error calculated by Fine/Marine was between 5% and 10%, trim and heave results were in good agreement with experimental results, and had greater accuracy compared with the empirical formula results. The feasibility of this numerical simulation method was validated and this method provided an effect performance evaluation method for new designing planing crafts.

scholarly journals Features of high-speed aircraft numerical simulation

2020 ◽  
Author(s):  
M.M. Alekseeva ◽  
N.A. Brykov ◽  
I.A. Vikhrova
Keyword(s):  
Numerical Simulation ◽  
Gas Dynamics ◽  
High Speed ◽  
Simulation Method ◽  
High Speed Flow ◽  
Flight Tests ◽  
High Speeds ◽  
Physical Experiments ◽  
Speed Flow ◽  
Flow Around A Body

Currently, the creation of new high-speed aircraft is of great interest. The development of such aircraft is associated with the need for experiments and flight tests. The organization of real physical experiments in the field of high speeds is fraught with significant difficulties that can be solved using the numerical simulation method, which makes it possible to significantly simplify the process of creating new products. When developing a high-speed aircraft, it is necessary to take into account the specific aerodynamic and thermophysical features of the processes occurring on the surface of the aircraft and in the shock layer. In this paper, the features of the processes at high speeds are considered on the example of solving the external and internal problems of the gas dynamics of an aircraft. Based on the specifics of these processes, we built a mathematical model that allows us to study the aerodynamics of a high-speed flow around a body in dense layers of the atmosphere and the processes that occur in the combustion chamber.

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