scholarly journals Numerical investigation of large-scale vortices in an array of cylinders in axial flow

2018 ◽  
Vol 78 ◽  
pp. 277-298 ◽  
Author(s):  
Laurent De Moerloose ◽  
Pieter Aerts ◽  
Jeroen De Ridder ◽  
Jan Vierendeels ◽  
Joris Degroote
Keyword(s):  
Numerical Investigation ◽  
Large Scale ◽  
Axial Flow ◽  
An Array Of Cylinders

Inlet Skew and the Growth of Secondary Losses and Vorticity in a Turbine Cascade

1989 ◽  
Author(s):  
J. A. Walsh ◽  
D. G. Gregory-Smith
Keyword(s):  
Experimental Investigation ◽  
Large Scale ◽  
Transverse Velocity ◽  
Axial Flow ◽  
Turbine Cascade ◽  
Streamwise Vorticity ◽  
Loss Prediction

This paper presents results of an experimental investigation into the effects of inlet skew on the flowfield of a large scale axial flow turbine cascade. The results are presented in terms of the development of the streamwise vorticity since, in classical terms, the streamwise vorticity generates the transverse velocity components that cause the generation of the secondary losses. Inlet skew is shown to have a profound effect on the distribution and magnitude of the generated losses. A number of correlations for the secondary losses are compared with the measured values and it is shown that the correlations are not adequate for accurate loss prediction purposes.

Analysis of a Large-Scale Cooling System Fan Gearbox Loads

2017 ◽  
Author(s):  
Charles H. O. Lombard ◽  
Daniel N. J. Els ◽  
Jacques Muiyser ◽  
Albert Zapke
Keyword(s):  
Large Scale ◽  
Cooling System ◽  
Axial Flow ◽  
Output Shaft ◽  
Blade Loading ◽  
Operational Conditions ◽  
Power Stations ◽  
Reverse Loading ◽  
Air Cooled Condensers ◽  
Input Side

South Africa’s coal-fired power stations use super heated steam to drive generator turbines. In arid regions, air-cooled condensers (ACCs) are used to condense the process steam. These ACCs consists of an array of over 200 axial flow fans, each driven by a motor via a reduction gearbox. Distorted fan inlet air flow conditions cause transient blade loading, which results in variations in output shaft bending and torque. A measurement project was conducted where the input and output shaft of such a gearbox were instrumented with strain gauges and wireless bridge amplifiers. Gearbox shaft speed and vibration were also measured. Torsional and bending strains were measured for a variety of operational conditions, where correlations were seen between gearbox loading and wind conditions. The input side experienced no unexpected loads from the motor or changing wind conditions, whereas output shaft loading was influenced by the latter. Digital filters were applied to identify specific bending components, such as the influence of fan hub misalignment and dynamic blade loading. Reverse loading of the gearbox was measured during the fan stop period, and vibration analysis revealed torsional and gearbox vibrations. This investigation documented reliable full scale ACC gearbox loads.

Numerical Investigation on the Separated Flow of Axial Flow Stator in Diagonal Flow Fan

2010 ◽  
Author(s):  
Yoichi Kinoue ◽  
Norimasa Shiomi ◽  
Toshiaki Setoguchi ◽  
Kenji Kaneko ◽  
Yingzi Jin ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Axial Flow ◽  
Separated Flow

1-D Model Analysis of Tesla Turbine for Small Scale Organic Rankine Cycle (ORC) System

2017 ◽  
Author(s):  
Jian Song ◽  
Chun-wei Gu
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Organic Rankine Cycle ◽  
Axial Flow ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Working Fluid ◽  
Small Scale ◽  
Low Grade ◽  
D Model

Energy shortage and environmental deterioration are two crucial issues that the developing world has to face. In order to solve these problems, conversion of low grade energy is attracting broad attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be one of the most effective methods for the utilization of low grade heat sources. Turbine is a key component in ORC system and it plays an important role in system performance. Traditional turbine expanders, the axial flow turbine and the radial inflow turbine are typically selected in large scale ORC systems. However, in small and micro scale systems, traditional turbine expanders are not suitable due to large flow loss and high rotation speed. In this case, Tesla turbine allows a low-cost and reliable design for the organic expander that could be an attractive option for small scale ORC systems. A 1-D model of Tesla turbine is presented in this paper, which mainly focuses on the flow characteristics and the momentum transfer. This study improves the 1-D model, taking the nozzle limit expansion ratio into consideration, which is related to the installation angle of the nozzle and the specific heat ratio of the working fluid. The improved model is used to analyze Tesla turbine performance and predict turbine efficiency. Thermodynamic analysis is conducted for a small scale ORC system. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.

scholarly journals Automated Compartment Model Development Based on Data from Flow-Following Sensor Devices

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1651
Author(s):  
Jonas Bisgaard ◽  
Tannaz Tajsoleiman ◽  
Monica Muldbak ◽  
Thomas Rydal ◽  
Tue Rasmussen ◽  
...  
Keyword(s):  
Large Scale ◽  
Model Development ◽  
Axial Flow ◽  
Compartment Model ◽  
Mixing Times ◽  
Flow Rates ◽  
Stirred Vessel ◽  
Compartment Models ◽  
Flow Models ◽  
Sensor Devices

Due to the heterogeneous nature of large-scale fermentation processes they cannot be modelled as ideally mixed reactors, and therefore flow models are necessary to accurately represent the processes. Computational fluid dynamics (CFD) is used more and more to derive flow fields for the modelling of bioprocesses, but the computational demands associated with simulation of multiphase systems with biokinetics still limits their wide applicability. Hence, a demand for simpler flow models persists. In this study, an approach to develop data-based flow models in the form of compartment models is presented, which utilizes axial-flow rates obtained from flow-following sensor devices in combination with a proposed procedure for automatic zoning of volume. The approach requires little experimental effort and eliminates the necessity for computational determination of inter-compartmental flow rates and manual zoning. The concept has been demonstrated in a 580 L stirred vessel, of which models have been developed for two types of impellers with varying agitation intensities. The sensor device measurements were corroborated by CFD simulations, and the performance of the developed compartment models was evaluated by comparing predicted mixing times with experimentally determined mixing times. The data-based compartment models predicted the mixing times for all examined conditions with relative errors in the range of 3–27%. The deviations were ascribed to limitations in the flow-following behavior of the sensor devices, whose sizes were relatively large compared to the examined system. The approach provides a versatile and automated flow modelling platform which can be applied to large-scale bioreactors.

Improved criteria for stall-free preliminary design of axial compressor of aero gas turbine engines

2018 ◽  
Vol 233 (9) ◽  
pp. 3286-3297 ◽  
Author(s):  
MR Aligoodarz ◽  
A Mehrpanahi ◽  
M Moshtaghzadeh ◽  
A Hashiehbaf
Keyword(s):  
Gas Turbine ◽  
Large Scale ◽  
Axial Compressor ◽  
Axial Flow ◽  
Design Criterion ◽  
Flow Coefficient ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Parameter Ranges ◽  
Axial Flow Compressors

A worldwide effort has been devoted to developing highly efficient and reliable gas turbine engines. There exist many prominent factors in the development of these engines. One of the most important features of the optimal design of axial flow compressors is satisfying the allowable range for various parameters such as flow coefficient, stage loading, the degree of reaction, De-Haller number, etc. But, there are some applicable cases that the mentioned criteria are exceeded. One of the most famous parameters is De-Haller number, which according to literature data should not be kept less than 0.72 in any stage of the axial compressor. A deep insight into the current small- or large-scale axial flow compressors shows that a discrepancy will occur among design criterion for De-Haller number and experimental measurements in which the De-Haller number is less than the design limit but no stall or surge is observed. In this paper, an improved formulation is derived based on one-dimensional modeling for predicting the stall-free design parameter ranges especially stage loading, flow coefficient, etc. for various combinations. It was found that the current criterion is much more accurate than the De-Haller criterion for design purposes.

Prospective of development of large-scale tidal current turbine array: An example numerical investigation of Zhejiang, China

2020 ◽  
Vol 264 ◽  
pp. 114621 ◽  
Author(s):  
Guizhong Deng ◽  
Zhaoru Zhang ◽  
Ye Li ◽  
Hailong Liu ◽  
Wentao Xu ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Tidal Current ◽  
Large Scale ◽  
Tidal Current Turbine ◽  
Current Turbine
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