scholarly journals Parametrization of High-Speed Train Streamline Shape

2017 ◽  
Author(s):  
Zhenxu Sun ◽  
Ye Zhang ◽  
Guowei Yang
Keyword(s):  
High Speed ◽  
Function Method ◽  
Shape Function ◽  
Transformation Method ◽  
Aerodynamic Performance ◽  
Aerodynamic Noise ◽  
Optimization Strategy ◽  
Deformation Method ◽  
Work Related ◽  
Vehicle Modeling Function

In the past decade, the high speed trains (HSTs) in China have experienced a booming development, with the design of CRH380A as a predominant example. A series of brand new HSTs have been developed with high aerodynamic performance, which includes the running resistance, the lift of the trailing car, pressure waves when trains pass by each other, aerodynamic noise in the far field, etc. In order to design HSTs with better aerodynamic performance, it is necessary to perform aerodynamic shape optimization, especially to optimize the streamline shape of HSTs. Parametrization is the basis for the whole optimization process, since good parametrization approach not only affects the optimization strategy, but also determines the design space and optimization efficiency. In the present paper, a series of work related to the streamline shape parametrization performed by the author in recent years have been introduced. Four different parametrization approaches have been exhibited, which are Local Shape Function method (LSF) and Free-Foam Deformation method (FFD), Modified Vehicle Modeling Function method (MVMF), Class function/Shape function Transformation method (CST). These methods could be categorized into two kinds: shape disturbance approach (LSF and FFD) and shape description approach (MVMF and CST). Among these four methods, some are developed by the authors while some are locally modified so as to meet the parametrization of the streamline shape. The detailed process of these four approaches are exhibited in the present paper and the characteristics of these four approaches are compared.

scholarly journals Double multiple stream tube theory coupled with dynamic stall and wake correction for aerodynamic investigation of vertical axis wind turbine

2020 ◽  
Vol 23 (4) ◽  
pp. 771-780
Author(s):  
Anh Ngoc VU ◽  
Ngoc Son Pham
Keyword(s):  
Wind Turbine ◽  
Shape Function ◽  
Vertical Axis ◽  
Transformation Method ◽  
Aerodynamic Performance ◽  
Dynamic Stall ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Stream Tube ◽  
Aerodynamic Investigation

This study describes an effectively analytic methodology to investigate the aerodynamic performance of H vertical axis wind turbine (H-VAWT). An in-house code based on double multiple stream tube theory (DMST) coupled with dynamic stall and wake correction is implemented to estimate the power coefficient. Design optimization of airfoil shape is conducted to study the influences of the dynamic stall and turbulent wakes. Airfoil shape is universally investigated by using the Class/Shape function transformation method. The airfoil study shows that the upper curve tends to be less convex than the lower curve in order to extract more energy of the wind upstream and generate less drag of the blade downstream. The optimal results show that the power coefficient increases by 6.5% with the new airfoil shape.

Numerical and Experimental Investigation on Centrifugal Cooling Fan in a Traction Motor

2018 ◽  
Author(s):  
Xiaoyun Qu ◽  
Jie Tian ◽  
Tong Wang
Keyword(s):  
High Speed ◽  
Aerodynamic Performance ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
High Speed Train ◽  
Traction Motor ◽  
Rotating Speed ◽  
Cooling Fan ◽  
Wide Range ◽  
Cfd Method

High-speed train is developing popular in China, which provides the convenient and fast transportation way, comparable to plane. The moving direction and speed of high-speed train is decided by the traction motor. Generally, a coaxial centrifugal fan is used to cool the motor and assemble in the motor casing. To ensure the reliability of the traction motor, more and more attention is paid to improve the performance of cooling fans in a wide range of rotating speed. As the train is designed to move in both directions, the traction motor is designed to rotate in both directions, so does the coaxial motor cooling fan. Symmetrical and straight blade structure is adopted to get the same performance of the fan in both forward and reverse moving directions. Therefore, the aerodynamic performance of the cooling fan is relatively not good enough, which results in relatively high aerodynamic noise. In order to analyze the cooling fan aerodynamic performance and aerodynamic noise, CFD method was performed on the full 3D model with the impeller-casing clearance. The acoustic analogy method was used to analyze the noise of the centrifugal cooling fan. In addition, the aerodynamic noise of the motor with the cooling fan was tested at different rotating speed in the semi-anechoic lab. The CFD method is verified and the results are in good agreement with the experimental results. The results show that it is necessary to consider the effects of impeller-casing leakage and the vacuum inlet condition in the simulated model to get its more accurate performance. Modified CFD model of the cooling fan was proposed here. It is suggested that the modified structure of the casing can be used to improve the performance of the cooling fan and reduce the corresponding aerodynamic noise.

scholarly journals Influence of the Topological Structures of the Nose of High-Speed Maglev Train on Aerodynamic Performances

2021 ◽  
Author(s):  
Yeteng Wang ◽  
Zhenxu Sun
Keyword(s):  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Design Method ◽  
Aerodynamic Performance ◽  
Superior Performance ◽  
Maglev Train ◽  
Topological Structures ◽  
Aerodynamic Shape ◽  
Vehicle Modeling Function

Abstract In the past few years, considerable attention has been paid to high-speed maglev train in the field of rail transit. The design speed of the high-speed maglev train is 600km/h, which is significantly higher than that of the high-speed train. With the increase in operating speed, high-speed maglev trains have higher requirements for aerodynamic shape. Superior performance, the beautiful aerodynamic shape is an important direction for the development of high-speed maglev trains. Based on the Vehicle Modeling Function (VMF) method, the current research has developed a parametric shape design method suitable for the aerodynamic shape of the maglev train’s nose. This method can obtain different topological structures of the high-speed maglev train’s nose. The current research uses this method to generate four maglev train noses with large appearance differences and uses these train noses to construct four simplified high-speed maglev models. Then this study numerically analyzes the flow fields of different train models and compares the differences in aerodynamic performance including aerodynamic drag, aerodynamic lift and wake characteristics. The Q-criterion is used to study the vortex structure and mechanism of different train wake regions, and the vortex propagation process is studied by turbulence kinetic energy (TKE). Studying the difference in the aerodynamic force of different topological shapes will help to improve the aerodynamic performance of high-speed maglev trains.

Effect of the strip spacing on the aerodynamic performance of a high-speed double-strip pantograph

2021 ◽  
pp. 1-17
Author(s):  
Zhiyuan Dai ◽  
Tian Li ◽  
Jian Deng ◽  
Ning Zhou ◽  
Weihua Zhang
Keyword(s):  
High Speed ◽  
Aerodynamic Performance

Numerical Calculation of Aerodynamic Noise for the Nose Cone Surface in High Speed Airflow Field

2014 ◽  
Vol 488-489 ◽  
pp. 886-891
Author(s):  
Ai Jian Zheng ◽  
Feng Niu ◽  
Hai Jiang Zhu
Keyword(s):  
Numerical Calculation ◽  
High Speed ◽  
Aerodynamic Noise ◽  
Element Analysis ◽  
Analysis Theory ◽  
Nose Cone ◽  
Flow Induced Noise ◽  
Airflow Field ◽  
Boundary Element Analysis ◽  
Acoustic Boundary Element

This paper presents two nose cones models and their numerical calculation of aerodynamic noise in high speed airflow field combining the analysis theory of fluid dynamics with the acoustic boundary element analysis method. The noise sound pressure levels (SPL) of these two models are calculated under the different speed airflow. And we compare the SPL of the better model with that of commercial nose cone models. These simulated results show that the aerodynamic noise of the nose cone with a ellipsoid head has lower flow-induced noise than that of commercial nose cone models at relative high air flow velocities at most frequencies.

Age-Related Differences in Throwing Techniques Used by the Catcher in Baseball

1994 ◽  
Vol 6 (3) ◽  
pp. 225-235 ◽  
Author(s):  
Shinji Sakurai ◽  
Bruce Elliott ◽  
J. Robert Grove
Keyword(s):  
High Speed ◽  
High Performance ◽  
Age Groups ◽  
Three Dimensional ◽  
Transformation Method ◽  
High Speed Photography ◽  
Two Phase ◽  
Ball Speed ◽  
Age Related ◽  
Release Speed

Three-dimensional (3-D) high speed photography was used to record the overarm throwing actions of five open-age, four 18-year-old, six 16-year- old, and six 14-year-old high-performance baseball catchers. The direct linear transformation method was used for 3-D space reconstruction from 2-D images of the catchers throwing from home plate to second base recorded using two phase-locked cameras operating at a nominal rate of 200 Hz. Selected physical capacity measures were also recorded and correlated with ball release speed. In general, anthropometric and strength measures significantly increased through the 14-year-old to open-age classifications, while a range of correlation coefficients from .50 to .84 was recorded between these physical capacities and ball speed at release. While many aspects of the kinematic data at release were similar, the key factors of release angle and release speed varied for the different age groups.

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