Noise Influence of High-Speed Train Based on Air Dynamics

2014 ◽  
Vol 687-691 ◽  
pp. 265-269
Author(s):  
Xiao Qin Wang
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Flow Distribution ◽  
Large Change ◽  
Aerodynamic Noise ◽  
Maximum Pressure ◽  
Air Conditioner ◽  
Test Results ◽  
Train Speed ◽  
Stable Flow

How to control aerodynamic noise of high speed motor train, this paper starts from the basic theory of hydrodynamics and acoustics, it adopts method of numerical simulation and applies Fluent and VirtuaUab Acousticsand software to make study on characteristics of aerodynamic noise for high speed motor train, the test results indicates that in the stable flow distribution, the baric gradient is relatively larger when its surface pressure is in area with large change in curve curvature, when it is in the area with even curve change, the baric gradient is relatively smaller. In different gradient, the train head, the maximum pressure and the maximum negative pressure ratio of air-conditioner air deflector predicate are in proportion to the square of train speed.

Performance of Strongly Bowed Stators in a Four-Stage High-Speed Compressor

2004 ◽  
Vol 126 (3) ◽  
pp. 333-338 ◽  
Author(s):  
Axel Fischer ◽  
Walter Riess ◽  
Joerg R. Seume
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Controlled Diffusion ◽  
Stage 4 ◽  
The University

The FVV sponsored project “Bow Blading” (cf. acknowledgments) at the Turbomachinery Laboratory of the University of Hannover addresses the effect of strongly bowed stator vanes on the flow field in a four-stage high-speed axial compressor with controlled diffusion airfoil (CDA) blading. The compressor is equipped with more strongly bowed vanes than have previously been reported in the literature. The performance map of the present compressor is being investigated experimentally and numerically. The results show that the pressure ratio and the efficiency at the design point and at the choke limit are reduced by the increase in friction losses on the surface of the bowed vanes, whose surface area is greater than that of the reference (CDA) vanes. The mass flow at the choke limit decreases for the same reason. Because of the change in the radial distribution of axial velocity, pressure rise shifts from stage 3 to stage 4 between the choke limit and maximum pressure ratio. Beyond the point of maximum pressure ratio, this effect is not distinguishable from the reduction of separation by the bow of the vanes. Experimental results show that in cases of high aerodynamic loading, i.e., between maximum pressure ratio and the stall limit, separation is reduced in the bowed stator vanes so that the stagnation pressure ratio and efficiency are increased by the change to bowed stators. It is shown that the reduction of separation with bowed vanes leads to a increase of static pressure rise towards lower mass flow so that the present bow bladed compressor achieves higher static pressure ratios at the stall limit.

Experimental Test Results for Four High-Speed, High-Pressure, Orifice-Compensated Hybrid Bearings

1994 ◽  
Vol 116 (1) ◽  
pp. 147-153 ◽  
Author(s):  
N. M. Franchek ◽  
D. W. Childs
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Orifice Diameter ◽  
Test Results ◽  
Rotordynamic Coefficients ◽  
Geometric Configurations ◽  
Overall Performance ◽  
Mass Terms

In this study, four hybrid bearings having different geometric configurations were experimentally tested for their static and dynamic characteristics, including flowrate, load capacity, rotordynamic coefficients, and whirl frequency ratio. The four bearings included a square-recess, smooth-land, radial-orifice bearing (baseline), a circular-recess bearing, a triangular-recess bearing, and an angled-orifice bearing. Each bearing had the same orifice diameter rather than the same pressure ratio. Unique to these test results is the measurement of the added mass terms, which became significant in the present tests because of high operating Reynolds numbers. Comparisons of the results were made between bearings to determine which bearing had the best performance. Based on the parameters of interest, the angled-orifice bearing has the most favorable overall performance.

Design and Test Results of a Ultra High Loaded Single Stage High Pressure Turbine

2013 ◽  
Author(s):  
Harjit S. Hura ◽  
Scott Carson ◽  
Rob Saeidi ◽  
Hyoun-Woo Shin ◽  
Paul Giel
Keyword(s):  
High Pressure ◽  
Total Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Single Stage ◽  
Test Results ◽  
High Pressure Turbine ◽  
Technology Program ◽  
High Pressure Ratio ◽  
Expected Performance

This paper describes the engine and rig design, and test results of an ultra-highly loaded single stage high pressure turbine. In service aviation single stage HPTs typically operate at a total-to-total pressure ratio of less than 4.0. At higher pressure ratios or energy extraction the nozzle and blade both have regions of supersonic flow and shock structures which, if not mitigated, can result in a large loss in efficiency both in the turbine itself and due to interaction with the downstream component which may be a turbine center frame or a low pressure turbine. Extending the viability of the single stage HPT to higher pressure ratios is attractive as it enables a compact engine with less weight, and lower initial and maintenance costs as compared to a two stage HPT. The present work was performed as part of the NASA UEET (Ultra-Efficient Engine Technology) program from 2002 through 2005. The goal of the program was to design and rig test a cooled single stage HPT with a pressure ratio of 5.5 with an efficiency at least two points higher than the state of the art. Preliminary design tools and a design of experiments approach were used to design the flow path. Stage loading and through-flow were set at appropriate levels based on prior experience on high pressure ratio single stage turbines. Appropriate choices of blade aspect ratio, count, and reaction were made based on comparison with similar HPT designs. A low shock blading design approach was used to minimize the shock strength in the blade during design iterations. CFD calculations were made to assess performance. The HPT aerodynamics and cooling design was replicated and tested in a high speed rig at design point and off-design conditions. The turbine met or exceeded the expected performance level based on both steady state and radial/circumferential traverse data. High frequency dynamic total pressure measurements were made to understand the presence of unsteadiness that persists in the exhaust of a transonic turbine.

A Study on Speed Elevation Possibility at the Connection between High Speed Lines and Conventional Lines with Korean High Speed Train

2006 ◽  
Vol 326-328 ◽  
pp. 635-638 ◽  
Author(s):  
Young Sam Ham ◽  
Jai Sung Hong
Keyword(s):  
Contact Force ◽  
High Speed ◽  
Integrated System ◽  
Communication Line ◽  
Mass Transportation ◽  
Test Results ◽  
High Speed Train ◽  
Safety Standards ◽  
Derailment Coefficient ◽  
Train Speed

Railways are a mass transportation system with high safety and punctuality. These strengths have been well proved by tests and evaluations. Railways are an integrated system with cars, power, signal, communication, line structures and operation. Among many safety standards of these systems, contact force between wheels and lines can be chosen since a derailment coefficient evaluated by contract force is the most important fact that decides the safety of railways. Especially regarding express trains, since they run twice faster than conventional ones, the evaluation of a derailment coefficient is more important than any other criteria. Currently, Korean express trains between Seoul and Pusan use the same stations as conventional trains in Daejeon and Dong-Daegu; therefore, express trains run on conventional lines from express lines. This paper describes test results acquired by increasing the train speed where express lines and conventional lines are connected. Test results tell that it is safe with under 0.8 derailment coefficient and running time is reduced by 10~30 seconds in each section.

Performance of Strongly Bowed Stators in a 4-Stage High Speed Compressor

2003 ◽  
Author(s):  
Axel Fischer ◽  
Walter Riess ◽  
Joerg R. Seume
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Controlled Diffusion ◽  
Stage 4 ◽  
The University

The FVV-sponsored-Project “Bow Blading” (c.f. acknowledgments) at the Turbomachinery Laboratory of the University of Hannover addresses the effect of strongly bowed stator vanes on the flow field in an 4-stage high speed axial compressor with controlled diffusion airfoil (CDA) blading. The compressor is equipped with more strongly bowed vanes than have previously been reported in the literature. The performance map of the present compressor is being investigated experimentally and numerically. The results show that the pressure ratio and the efficiency at the design point and at the choke limit are reduced by the increase in friction losses on the surface of the bowed vanes, whose surface area is greater than that of the reference (CDA) vanes. The mass flow at the choke limit decreases for the same reason. Because of the change in the radial distribution of axial velocity, pressure rise shifts from stage 3 to stage 4 between the choke limit and maximum pressure ratio. Beyond the point of maximum pressure ratio, this effect is not distinguishable from the reduction of separation by the bow of the vanes. Experimental results show that in cases of high aerodynamic loading, i.e. between maximum pressure ratio and the stall limit, separation is reduced in the bowed stator vanes so that the stagnation pressure ratio and efficiency are increased by the change to bowed stators. It is shown that the reduction of separation with bowed vanes leads to a increase of static pressure rise towards lower mass flow so that the present bow bladed compressor achieves higher static pressure ratios at the stall limit.

Vibration Characteristics of a 75kW Turbo Machine With Air Foil Bearings

2006 ◽  
Vol 129 (3) ◽  
pp. 843-849 ◽  
Author(s):  
Kyeong-Su Kim ◽  
In Lee
Keyword(s):  
High Speed ◽  
Performance Test ◽  
Pressure Ratio ◽  
Vibration Characteristics ◽  
Operating Conditions ◽  
Maximum Pressure ◽  
Stable Operation ◽  
Foil Bearings ◽  
Wide Range ◽  
Free Environment

Air foil bearings are very attractive bearing systems for turbomachinery because they have several advantages over conventional bearings in terms of oil-free environment, low power loss, long life, and no maintenance. However, most of the developed machines using air foil bearings are limited to small and high-speed rotors of 60,000–120,000 rpm, since the increase in power of turbomachinery requires lower rotor speed and greater loading in bearings, which makes it difficult to use air foil bearings for large machines. In this paper, a 75 kW turboblower using air foil bearings is introduced, and the vibration characteristics of the machine have been investigated experimentally under a wide range of operating conditions, including compressor surge in the performance test. The machine is designed to be fully air lubricated and air cooled, and its operating speed is 20,000–26,000 rpm with maximum pressure ratio of 1.8. The results show that the air foil bearings offer adequate damping to ensure dynamically stable operation in the whole range.

Aerodynamic Effects of Unvented Hoods on the Initial Compression Wave Generated by a High-Speed Train Entering a Tunnel

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Xintao Xiang ◽  
Leiping Xue ◽  
Benlong Wang
Keyword(s):  
Pressure Gradient ◽  
Compression Wave ◽  
High Speed ◽  
Maximum Pressure ◽  
High Speed Train ◽  
Main Aspect ◽  
Section Area ◽  
Tunnel Section ◽  
Train Speed ◽  
The Relationship

The influence of unvented hood on the initial compression wave generated by a high-speed train entering a tunnel is investigated using computational fluid dynamics. Comparisons with experimental data are first carried out to verify the numerical model. The relationship between the pressure gradient peaks and main aspect factors is studied by parametric analysis. Influences of train speed, blockage ratio of train to tunnel, section area ratio of hood to tunnel, and hood length are investigated. Based on the numerical results, two empirical formulations are proposed to predict the influence of hood and tunnel geometries on the maximum pressure gradient during the CRH3 entering a tunnel with unvented hood.

scholarly journals Validation of a Radial Compressor CFD Analysis

2020 ◽  
Vol 3 (1) ◽  
pp. 85-90
Author(s):  
Süleyman Emre Ak ◽  
Sertaç Çadırcı
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Ideal Gas ◽  
Cfd Analysis ◽  
Test Results ◽  
Radial Compressor ◽  
Computational Fluid Dynamics Cfd ◽  
Relative Errors ◽  
Mesh Convergence ◽  
The Ideal

In this study, a radial compressor flow at a high speed is investigated by Computational Fluid Dynamics (CFD) methods. The radial compressor of interest consists of a rotor, diffuser, and exit guide vanes and has an operational rotational speed of 21789 rpm. The geometry of the compressor and its test results such as compression ratio and adiabatic efficiency are available in literature. After extensive mesh convergence tests, steady-state CFD analysis has been performed for compressible and turbulent flow using the ideal gas approach. The main motivation of the study is the determine the appropriate CFD approach and boundary conditions of the problem that will fit best to the measurements. The CFD analysis revealed that the maximum relative errors for the adiabatic efficiency and the pressure ratio were 3.6 % and 1.3 %, respectively.

scholarly journals Levels of vibration transmitted to the operator of the tractor equipped with front axle suspension

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Daniele Pochi ◽  
Roberto Fanigliulo ◽  
Laura Fornaciari ◽  
Gennaro Vassalini ◽  
Marco Fedrizzi ◽  
...  
Keyword(s):  
High Speed ◽  
Travel Speed ◽  
Front Axle ◽  
Operating Conditions ◽  
Road Surface ◽  
Air Conditioner ◽  
Test Results ◽  
The Road ◽  
Seat Suspension ◽  
Agricultural Tractors

In recent years the comfort and the preservation of the health of the operators became central issues in the evolution of agricultural machinery and led to the introduction of devices aimed at improving working conditions. Thereby, for instance, the presence of air conditioner, soundproof cab and driver seat suspension became normal on agricultural tractors. The vibrations are one of the most complex issues to deal with, being determined by the characteristics and interaction of elements such as tyres, axles, mainframe, cab and seat suspension. In this respect, manufacturers are trying to improve their products, even integrating these elements with new devices such as the suspension on the front axle of the tractor, aimed at reducing the level of vibrations during the transfers at high speed. One of these underwent tests at CRA-ING. Since its purpose is to reduce the level of vibration transmitted to the driver, their measurements in different points of the tractor and in different operating conditions, were compared in order to evaluate the effectiveness of the device, expressed as time of exposure. The suspension system of the front axle is designed to absorb the oscillations (especially pitching) determined by irregularities in the road surface, allowing an increased control of the vehicle at high speed, as demonstrated by the test results and confirmed by the driving impressions outlined by the operator. The action of the device under these conditions results in an increase of the exposure time, important fact because of the relevance of the road transfer operations of tractors with mounted implements or trailers to tow and of the tendency to increase the speed limit for the road tractors (in Germany were brought to 50 km h–1 for several years). The action just described is less evident with increasing irregularity of the road surface and with the decrease of the travel speed. Nevertheless, in such conditions, the device appears to positively work along the other directions, in particular in the Z-axis, improving the action of the suspension of the driver seat.

scholarly journals Theoretical and experimental investigation on maximum pressure loads of labyrinth seal’s teeth

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401879434 ◽  
Author(s):  
Jie Jiang ◽  
Yiyong Yang ◽  
Yongjian Li ◽  
Weifeng Huang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Ratio ◽  
Labyrinth Seal ◽  
Maximum Pressure ◽  
Test Results ◽  
Dynamics Model ◽  
Computational Fluid Dynamics Model ◽  
Pressure Load ◽  
Sound Structure

The pressure loads acting on the teeth of a labyrinth seal are usually not uniform. Sometimes, one tooth would take almost half of the total pressure difference, which is detrimental to the teeth’s working life and sealing effect. Therefore, the estimation of maximum pressure load on the teeth is helpful to design a sound structure of labyrinth seal. This article analyzes the influence of teeth number, boundary condition, clearances, and structure parameters on maximum pressure loads of labyrinth seal teeth in low pressure ratio conditions ( PR≤ 0.5, PR = Pout/ Pin). Both the computational fluid dynamics model and test results show that teeth number and pressure load are main factors influencing the maximum pressure load on teeth. Finally, a fitting equation is given to estimate the maximum pressure load on labyrinth seal teeth and its results are in good agreement with the computational fluid dynamics model.

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