scholarly journals Investigation of the Unsteady Flow Generated by an Axial Fan: Experimental Testing and Simulations

2005 ◽  
Vol 2005 (3) ◽  
pp. 256-263 ◽  
Author(s):  
R. S. Amano ◽  
E. K. Lee ◽  
C. Xu ◽  
Jianhui Xie
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Flow Measurement ◽  
Cfd Simulation ◽  
Experimental Testing ◽  
Strain Analysis ◽  
Test Facility ◽  
Axial Fan ◽  
Complex Flow ◽  
Fea Simulation

The unsteady flow measurement of a large axial fan with diameter 1.829m (6 ft) has been carried out. The complex flow field generated by the fan is investigated through experimental testing and CFD/FEA simulation. The results presented in this paper can be divided into three parts. The first part consists of the experimental description of the test facility, velocity measurement, flow-field visualization, and stress/strain analysis of the fan blades. The second part consists of the CFD simulation of the flow field. Simulation is carried out to analyze the flow pattern with and without a radiator attached to the fan casing. The results presented in this paper can be used as a reference for axial fan performance improvement in the future.

Analysis of dynamic stall flow field of high bypass fan rotor based on airworthiness certification

2020 ◽  
Vol 234 (11) ◽  
pp. 1757-1769
Author(s):  
Kai Zhang ◽  
AJ Wang
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Field Data ◽  
Decomposition Methods ◽  
Modal Identification ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Complex Flow ◽  
Mode Decomposition ◽  
Proper Orthogonal

In order to ensure flight safety, the stall test is one of the most important steps in the airworthiness certification phase of civil aircraft. The twisted-swept fan is one of the most important components of the high bypass ratio engine. The unsteady flow field of the fan rotor stall condition is obtained by numerical simulation. At the same time, the time series flow field data of the stall condition flow field is acquired. The modal analysis of the unsteady flow field at stall condition was performed using the dynamic mode decomposition and proper orthogonal decomposition methods. Through modal identification of a large number of unsteady flow field data, the eigenvalues and corresponding modal information about the unsteady flow field change process are obtained. Finally, the evolution process of the unsteady flow field of the fan rotor under stall condition is visually demonstrated, and the coherent structures of different scales in the complex flow field under stall condition are revealed.

Research Analysis and Experiment Study on Flow Field of Hydrodynamic Coupling

2011 ◽  
Vol 418-420 ◽  
pp. 2006-2011
Author(s):  
Rui Zhang ◽  
Cheng Jian Sun ◽  
Yue Wang
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Internal Flow ◽  
Phase Flow ◽  
Complex Flow ◽  
Two Phase ◽  
Operation Conditions ◽  
Hydrodynamic Coupling

CFD simulation and PIV test technology provide effective solution for revealing the complex flow of hydrodynamic coupling’s internal flow field. Some articles reported that the combination of CFD simulation and PIV test can be used for analyzing the internal flow field of coupling, and such analysis focuses on one-phase flow. However, most internal flow field of coupling are gas-fluid two-phase flow under the real operation conditions. In order to reflect the gas-fluid two-phase flow of coupling objectively, CFD three-dimensional numerical simulation is conducted under two typical operation conditions. In addition, modern two-dimensional PIV technology is used to test the two-phase flow. This method of combining experiments and simulation presents the characteristics of the flow field when charging ratios are different.

Visualizations of the Unsteady Flow Field Near the Endwall of a Compressor Cascade

2001 ◽  
Author(s):  
Hongwei Ma ◽  
Haokang Jiang ◽  
Lin Yang
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Cross Sections ◽  
Leading Edge ◽  
Light Sheet ◽  
Horseshoe Vortex ◽  
Radial Clearance ◽  
Compressor Cascade ◽  
Complex Flow ◽  
Suction Surface

This paper presents flow visualizations of the unsteady flow field near the endwall of a compressor cascade. The experiments were performed in a water tunnel using the hydrogen bubble technique. A Pt wire was positioned parallel to the endwall and ahead of the cascade at 2% span from the endwall. The traces of hydrogen bubbles generated by the wire were visualized within a light sheet arranged at various cross-sections around the cascade. The unsteady flow field was visualized at different incidences without a radial clearance. A periodically fluctuating horseshoe vortex system of varying number of vortices is observed near the leading edge of the cascade, which plays a leading role in the flow field near the endwall. The interaction and the flow mixing among the counter-rotating horseshoe legs, the endwall boundary layer and the main flow, periodically occur in the passage. Breakdown of the horseshoe vortex is clearly observed in the cascade while the unsteady and complex flow field is shown at the corner of the suction surface.

scholarly journals Investigation on Dynamic Stresses of Pump-Turbine Runner during Start Up in Turbine Mode

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 499
Author(s):  
Funan Chen ◽  
Huili Bi ◽  
Soo-Hwang Ahn ◽  
Zhongyu Mao ◽  
Yongyao Luo ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Unsteady Flow ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Leading Edge ◽  
Complex Flow ◽  
Dynamic Stresses ◽  
Start Up ◽  
Pumped Storage ◽  
Turbine Mode

The startup process occurs frequently for pumped storage units. During this process, the rotating rate that changes rapidly and unsteady flow in runner cause the complex dynamic response of runner, sometimes even resonance. The sharp rise of stress and the large-amplitude dynamic stresses of runner will greatly shorten the fatigue life. Thus, the study of start-up process in turbine mode is critical to the safety operation. This paper introduced a method of coupling one dimensional (1D) pipeline calculation and three-dimensional computational dynamics (3D CFD) simulation to analyze transient unsteady flow in units and to obtain more accurate and reliable dynamic stresses results during start up process. According to the results, stress of the ring near fixed support increased quickly as rotating rate rose and became larger than at fillets of leading edge and band in the later stages of start-up. In addition, it was found that dynamic response can be caused by rotor stator interaction (RSI), but also could even be generated by the severe pressure fluctuation in clearance, which can also be a leading factor of dynamic stresses. This study will facilitate further estimation of dynamic stresses in complex flow and changing rotating rate cases, as well as fatigue analysis of runner during transient operation.

On the Influence of an Acoustically Optimized Turbine Exit Casing Onto the Unsteady Flow Field Downstream of a Low Pressure Turbine Rotor

2018 ◽  
Author(s):  
L. Simonassi ◽  
M. Zenz ◽  
S. Zerobin ◽  
F. Heitmeir ◽  
A. Marn ◽  
...  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Low Noise ◽  
Test Facility ◽  
Pressure Probe ◽  
Guide Vanes ◽  
Low Pressure Turbine ◽  
Aerodynamic Pressure

Modern low pressure turbines (LPT) are designed in order to fulfil a various number of requirements such as high endurance, low noise, high efficiency, low weight and low fuel consumption. Regarding the reduction of the emitted noise, different designs of low pressure turbine exit guide vanes (aerodynamically and/or acoustically optimized) of the turbine exit casing (TEC) were tested and their noise reduction capabilities and aerodynamic performance were evaluated. In particular, measurements of TEC-losses were performed and differences in the losses were reported. Measurements were carried out in a one and a half stage subsonic turbine test facility at the engine relevant operating point approach. This work focuses on the study of the unsteady flow field downstream of an unshrouded low pressure turbine rotor. The influence on the upstream flow field of a TEC design including acoustically optimized vanes (Inverse cut-off TEC) is investigated and compared with a second TEC configuration without vanes (Vaneless TEC), by means of fast response aerodynamic pressure probe measurements. The second configuration served as a reference concerning the influence of TEGVs onto the upstream located LPT rotor. The interactions between the stator and rotor wakes, secondary flows and the turbine exit guide vanes potential effect are identified via modal decomposition according to the theory of Tyler and Sofrin. The main structures constituting the unsteady flow field are detected and the role of the major interaction effects in the loss generation mechanism and in the acoustic emission is analysed. This study based on the modal analysis of the unsteady flow field offers new insight into the main interaction mechanisms and their importance in the assessment of the aerodynamic and aeroelastic performance of modern low pressure turbine exit casings.

Accurate marine propellers flow field CFD through anisotropic mesh optimization

2019 ◽  
Vol 29 (9) ◽  
pp. 3148-3168
Author(s):  
Ahmed Abou El-Azm Aly ◽  
Wagdi G. Habashi
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Computational Cost ◽  
Open Water ◽  
Mesh Optimization ◽  
Complex Flow ◽  
Anisotropic Mesh ◽  
Content Type ◽  
Marine Propellers ◽  
Thrust And Torque

Purpose Computational fluid dynamics (CFD) simulation of the flow field around marine propellers is challenging because of geometric complexity and rotational effects. To capture the flow structure, grid quality and distribution around the blades is primordial. This paper aims to demonstrate that solution-based automatic mesh optimization is the most logical and practical way to achieve optimal CFD solutions. Design/methodology/approach In the current paper, open water propeller performance coefficients such as thrust and torque coefficients are numerically investigated. An anisotropic mesh adaptation technique is applied, believed for the first time, to marine propellers and to two computational domains. Findings The current study’s performance coefficients are compared with other previously published CFD results and improvements in terms of accuracy and computational cost are vividly demonstrated for different advance coefficients, as well as a much sharper capture of the complex flow features. Originality/value It will be clearly demonstrated that these two improvements can be achieved, surprisingly, at a much lower meshing and computational cost.

scholarly journals The study of typical water header flow structure by LES and RANS

2021 ◽  
pp. 293-293
Author(s):  
Hao Qin ◽  
Bin Wang ◽  
Yun Guo ◽  
Miao Hu
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
System Analysis ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Rapid Change ◽  
Convergence Criteria ◽  
Complex Flow ◽  
Complex Flow Structure ◽  
Rans Method

Water header is the most common structure in the design of flow system for energy and power system. The complex flow structure could result in some problems when Computational Fluid Dynamic (CFD) simulation is applied in the whole system analysis. The rapid change in velocity distribution of the flow field leads to difficulties to create suitable boundary layer mesh, and the complex flow structure will also make residuals hard to reach convergence criteria. Large Eddy Simulation (LES) is promising to promote these studies, it is more accurate than RANS method and can capture many non-steady state characteristics those RANS method can?t obtain. In this study a typical water header flow structure is investigated by RANS and LES methods. By comparing the detailed flow structures in the results of two methods, the deficiency of RANS method was found. The results of LES can be used to guide the establishment of meshes and the application of time-averaged turbulence models to improve efficiency in engineering. And the asymmetric Reynolds stresses may induce asymmetric flow field in symmetric geometry.

A Model for Cylindrical Hole Film Cooling—Part II: Model Formulation, Implementation and Results

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Tilman auf dem Kampe ◽  
Stefan Völker
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Experimental Investigations ◽  
Source Terms ◽  
Complex Flow ◽  
General Applicability ◽  
Cooling Hole

A model to simulate flows ejected from cylindrical film cooling holes in 3D-CFD without meshing the cooling hole geometry has been developed. It uses a correlation-based prediction of the complete three-dimensional flow field in the vicinity of a film hole exit based on characteristic film cooling parameters that is presented in part I of this two-part paper. The model describes the film-jet in terms of its shape and the distribution of temperature and velocity components within the film-jet body. For example, the characteristic counter-rotating vortex pair in the film-jet is modeled. Adding source terms to the transport equations for mass, momentum, and energy locally, the correlation-based prediction of the film-jet flow field is imposed onto a 3D-CFD simulation. Source terms are specified in the vicinity of a film hole exit, within a region representative of the volume occupied by the film jet. Each node within this source volume is treated individually in order to model the complex flow structure of the film-jet. The model has successfully been implemented in a commercial CFD code. Its general applicability has been tested and proven. The model’s predictive capability is compared to detailed CFD calculations and experimental investigations. A grid requirement study has been conducted, showing that the film cooling model delivers reasonable predictions of the surface temperature distributions downstream of the ejection location using relatively coarse grids. A minimum grid resolution requirement has been identified.

A Model for Cylindrical Hole Film Cooling: Part II—Model Formulation, Implementation and Results

2010 ◽  
Author(s):  
Tilman auf dem Kampe ◽  
Stefan Vo¨lker
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Experimental Investigations ◽  
Source Terms ◽  
Complex Flow ◽  
General Applicability ◽  
Cooling Hole

A model to simulate flows ejected from cylindrical film cooling holes in 3D-CFD without meshing the cooling hole geometry has been developed. It uses a correlation-based prediction of the complete three-dimensional flow field in the vicinity of a film hole exit based on characteristic film cooling parameters that is presented in part I of this two-part paper [1]. The model describes the film-jet in terms of its shape and the distribution of temperature and velocity components within the film-jet body. For example, the characteristic counter-rotating vortex pair in the film-jet is modeled. Adding source terms to the transport equations for mass, momentum and energy locally, the correlation-based prediction of the film-jet flow field is imposed onto a 3D-CFD simulation. Source terms are specified in the vicinity of a film hole exit, within a region representative of the volume occupied by the film jet. Each node within this source volume is treated individually in order to model the complex flow structure of the film-jet. The model has successfully been implemented in a commercial CFD code. Its general applicability has been tested and proven. The model’s predictive capability is compared to detailed CFD calculations and experimental investigations. A grid requirement study has been conducted, showing that the film cooling model delivers reasonable predictions of the surface temperature distributions downstream of the ejection location using relatively coarse grids. A minimum grid resolution requirement has been identified.

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