Experimental Investigation on Aerodynamic Unsteadiness in a Full Scale Gas Turbine Midframe Sector

2013 ◽  
Author(s):  
Matthew J. Golsen ◽  
Jahed Hossain ◽  
Anthony Bravato ◽  
John Harrington ◽  
Joshua Bernstein ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Mean Flow ◽  
Complex Flow ◽  
Inlet Conditions ◽  
Complicated Geometry ◽  
Downstream Flow ◽  
Complicated Geometries ◽  
Flow Experiments

Aerodynamic unsteadiness generated upstream of the combustor basket via the complicated geometry of a modern gas turbine can lead to incomplete combustion, reduced efficiency, greater pressure drop, flashback, and reduced part life. The MidFrame section encompasses the main gas path from the compressor exit to the turbine inlet. Diffuser performance, support struts, transition pieces, and other flow obstructing geometries can lead to flow unsteadiness which can reduce performance. This study uses a combination of thermal anemometry, pressure microphone, and wall mounted accelerometer measurements to determine the primary unsteadiness frequencies and target their source. Diffuser performance is shown to have a significant impact on the downstream flow behavior. Inlet conditions are modified to provide a separated bottom wall and a fully attached compressor exit diffuser (CED) condition at an area average inlet Mach number of 0.26. Unsteadiness levels are seen to increase as a result of the separated inlet condition while the mean flow characteristics are slightly altered due to the varying exit trajectory of the main core from the CED, nevertheless the overall level of unsteadiness/turbulence is low for such a complex flow field (8 to 11 %). Results of this study can help diagnose and prevent the aforementioned issues for complicated geometries where simple flow experiments fall short.

scholarly journals Spectral-Element Simulation of the Turbulent Flow in an Urban Environment

2021 ◽  
Author(s):  
Maxime Stuck ◽  
Alvaro Vidal ◽  
Pablo Torres ◽  
Hassan M. Nagib ◽  
Candace Wark ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Urban Environment ◽  
Good Description ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Mean Flow ◽  
Complex Flow ◽  
Turbulence Statistics ◽  
Experimental Database ◽  
The Impact

The mean flow and turbulence statistics of the flow through a simplified urban environment, which is an active research area in order to improve the knowledge of turbulent flow in cities, is investigated. This is useful for civil engineering, pedestrian comfort and for health concerns caused by pollutant spreading. In this work, we provide analysis of the turbulence statistics obtained from well-resolved large-eddy simulations (LES). A detailed analysis of this database reveals the impact of the geometry of the urban array on the flow characteristics and provides for a good description of the turbulent features of the flow within a simplified urban environment. The most prominent features of this complex flow include coherent vortical structures such as the so-called arch vortex, the horseshoe vortex and the roof vortex. These structures of the flow have been identified by an analysis of the turbulence statistics. The influence of the geometry of the urban environment (and particularly the street width and the building height) on the overall flow behavior have also been studied. Finally, the well-resolved LES results were compared with the experimental database from Monnier et al. to discuss differences and similarities between the respective urban configurations.

scholarly journals Spectral-Element Simulation of the Turbulent Flow in an Urban Environment

2021 ◽  
Vol 11 (14) ◽  
pp. 6472
Author(s):  
Maxime Stuck ◽  
Alvaro Vidal ◽  
Pablo Torres ◽  
Hassan M. Nagib ◽  
Candace Wark ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Urban Environment ◽  
Good Description ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Mean Flow ◽  
Complex Flow ◽  
Turbulence Statistics ◽  
Experimental Database ◽  
The Impact

The mean flow and turbulence statistics of the flow through a simplified urban environment, which is an active research area in order to improve the knowledge of turbulent flow in cities, is investigated. This is useful for civil engineering, pedestrian comfort and for health concerns caused by pollutant spreading. In this work, we provide analysis of the turbulence statistics obtained from well-resolved large-eddy simulations (LES). A detailed analysis of this database reveals the impact of the geometry of the urban array on the flow characteristics and provides for a good description of the turbulent features of the flow within a simplified urban environment. The most prominent features of this complex flow include coherent vortical structures such as the so-called arch vortex, the horseshoe vortex and the roof vortex. These structures of flow have been identified by an analysis of the turbulence statistics. The influence of the geometry of urban environment (and particularly the street width and the building height) on the overall flow behavior has also been studied. Finally, the well-resolved LES results were compared with an available experimental database to discuss differences and similarities between the respective urban configurations.

scholarly journals Computational study on the aerodynamics of a long-shrouded contra-rotating rotor in hover

2019 ◽  
Vol 11 ◽  
pp. 175682931983368
Author(s):  
Chao Huo ◽  
Peng Lv ◽  
Anbang Sun
Keyword(s):  
Flow Field ◽  
Opposite Direction ◽  
Computational Study ◽  
Flow Characteristics ◽  
The Other ◽  
Complex Flow ◽  
Sliding Mesh ◽  
Global Performance ◽  
Mesh Method ◽  
Downstream Flow

This paper aims to investigate the aerodynamics including the global performance and flow characteristics of a long-shrouded contra-rotating rotor by developing a full 3D RANS computation. Through validations by current experiments on the same shrouded contra-rotating rotor, the computation using sliding mesh method and the computational zone with an extended nozzle downstream flow field effectively works; the time-averaged solution of the unsteady computation reveals that more uniform flow presents after the downstream rotor, which implies that the rear rotor rotating at opposite direction greatly compensates and reduces the wake; the unsteady computations further explore the flow field throughout the whole system, along the span and around blade tips. Complex flow patterns including the vortices and their interactions are indicated around the blade roots and tips. For further identifying rotor configurations, the rotor–rotor distance and switching two rotor speeds were studied. The computation reveals that setting the second rotor backwards decreases the wake scale but increases its intensity in the downstream nozzle zone. However, for the effect of switching speeds, computations cannot precisely solve the flow when the rear rotor under the windmill because of the upstream rotor rotating much faster than the other one. All the phenomena from computations well implement the experimental observations.

scholarly journals PIV measurement of complex flow characteristics in open-cell metal foam replica

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Minsin Kim ◽  
Youngwoo Kim ◽  
Sajjad Hosseini ◽  
Kyung Chun Kim
Keyword(s):  
Reynolds Number ◽  
Metal Foam ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Complex Flow ◽  
Time Resolved ◽  
Open Cell ◽  
Flow Disturbances ◽  
Piv Measurement ◽  
Inlet Conditions

Time-resolved 2-D particle image velocimetry was used to study on turbulent flow characteristics inside an open-cell metal foam under the laminar and turbulent inlet conditions. A study on the effect of Reynolds number was conducted with different three channel Reynolds numbers, 1000, 5000 and 10000. Uniform upstream flow is divided by the pore network of metal foam and it is found that there are flow disturbances induced by metal foam structure even at a laminar inlet condition. It is confirmed that there is a similarity of the preferred flow path flows take regardless of Reynolds number.

Analysis on Flow Behavior in the Plenum of RPV of PWR

2018 ◽  
Author(s):  
Lei Huang ◽  
Lu-lu Hao ◽  
Hong Chen ◽  
Jun-feng Xue ◽  
Li-li Tong
Keyword(s):  
Flow Direction ◽  
Flow Behavior ◽  
Complex Structure ◽  
Flow Characteristics ◽  
Flow Distribution ◽  
Cylinder Wall ◽  
Operation Condition ◽  
Pressurized Water ◽  
Inlet Conditions ◽  
Flow Flux

The flow distribution at core inlet plays a vital part on hydraulic design of pressurized water reactor. Nonuniform coolant flow distribution at core inlet is caused by many factors, among which the behavior of flow in the lower plenum is the most direct cause. Therefore, a further research on the flow behavior of coolant in the lower plenum is very important and necessary. However, the flow behavior is dominated by the variation of the flow environment related to the complex structure and the condition of upstream uniformity. Using CFD methods, the flow field in the pressure vessel under the uniform flux operation condition of three-loops is simulated in this paper. The standard k–ε turbulence model and upwind solver scheme are selected. Pressure and velocity along with the flow direction are investigated. The variation trend of flow characteristics is discussed by analysis on streamlines at different locations ranging from inlet pipe to lower core plate, which provides evidence for the formation of swirling eddies in the lower plenum and uneven flow flux at lower core plate. In order to understand the formation process of eddies of different sizes in the lower plenum, the velocity fields in the downcomer and lower plenum under the conditions of different inlet velocity are analyzed. Furthermore, the effects of key structures on the formation of swirl are also presented. The results show that the value of velocity flowing into the lower plenum is an important factor on the range of vertical reflux effect, also slowing down because of the resistance of the vortex suppression plate. And the value of angular momentum of swirls in the lower plenum is mainly determined by the inlet angle of converging streams flowing from the downcomer, which is caused by dispersed flow along the cylinder wall flowing from two cold legs, related with the inlet conditions.

A Sensitivity Study of Gas Turbine Exhaust Diffuser-Collector Performance at Various Inlet Swirl Angles and Strut Stagger Angles

2017 ◽  
Author(s):  
Michal P. Siorek ◽  
Stephen Guillot ◽  
Song Xue ◽  
Wing F. Ng
Keyword(s):  
Gas Turbine ◽  
Flow Direction ◽  
Flow Behavior ◽  
Exhaust System ◽  
Sensitivity Study ◽  
Inlet Swirl ◽  
Inlet Conditions ◽  
Gas Turbine Exhaust ◽  
The Impact ◽  
Turbine Exhaust

This paper describes studies completed using a quarter-scaled rig to assess the impact of turbine exit swirl angle and strut stagger on a turbine exhaust system consisting of an integral diffuser-collector. Advanced testing methods were applied to ascertain exhaust performance for a range of inlet conditions aerodynamically matched to flow exiting an industrial gas turbine. Flow visualization techniques along with complementary Computational Fluid Dynamics (CFD) predictions were used to study flow behavior along the diffuser endwalls. Complimentary CFD analysis was also completed with the aim to ascertain the performance prediction capability of modern day analytical tools for design phase and off-design analysis. The K-Epsilon model adequately captured the relevant flow features within both the diffuser and collector, and the model accurately predicted the recovery at design conditions. At off-design conditions, the recovery predictions were found to be pessimistic. The integral diffuser-collector exhaust accommodated a significant amount of inlet swirl without a degradation in performance, so long as the inlet flow direction did not significantly deviate from the strut stagger angle. Strut incidence at the hub was directly correlated with reduction in overall performance, whereas the diffuser-collector performance was not significantly impacted by strut incidence at the shroud.

A Sensitivity Study of Gas Turbine Exhaust Diffuser-Collector Performance at Various Inlet Swirl Angles and Strut Stagger Angles

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Michal P. Siorek ◽  
Stephen Guillot ◽  
Song Xue ◽  
Wing F. Ng
Keyword(s):  
Gas Turbine ◽  
Flow Direction ◽  
Flow Behavior ◽  
Exhaust System ◽  
Sensitivity Study ◽  
Inlet Swirl ◽  
Inlet Conditions ◽  
Gas Turbine Exhaust ◽  
The Impact ◽  
Turbine Exhaust

This paper describes studies completed using a quarter-scaled rig to assess the impact of turbine exit swirl angle and strut stagger on a turbine exhaust system consisting of an integral diffuser-collector. Advanced testing methods were applied to ascertain exhaust performance for a range of inlet conditions aerodynamically matched to flow exiting an industrial gas turbine. Flow visualization techniques along with complementary computational fluid dynamics (CFD) predictions were used to study flow behavior along the diffuser end walls. Complimentary CFD analysis was also completed with the aim to ascertain the performance prediction capability of modern day analytical tools for design phase and off-design analysis. The K-Epsilon model adequately captured the relevant flow features within both the diffuser and collector, and the model accurately predicted the recovery at design conditions. At off-design conditions, the recovery predictions were found to be pessimistic. The integral diffuser-collector exhaust accommodated a significant amount of inlet swirl without degradation in performance, so long as the inlet flow direction did not significantly deviate from the strut stagger angle. Strut incidence at the hub was directly correlated with reduction in overall performance, whereas the diffuser-collector performance was not significantly impacted by strut incidence at the shroud.

CFD Analyses of Flow in a Gas Turbine Combustor Swirl Cup

2017 ◽  
Author(s):  
Srinivasan Karuppannan ◽  
Bhirud Mehul ◽  
Gullapalli Sivaramakrishna ◽  
Raju D. Navindgi ◽  
N. Muthuveerappan
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Operating Regime ◽  
Gas Turbine Combustor ◽  
Ansys Fluent ◽  
Turbine Engine ◽  
Downstream Flow ◽  
Cfd Analyses

Swirl cups (hybrid atomizers) are being widely employed in aero gas turbine engine combustors for their established merits in terms of achieving satisfactory atomization over the entire combustor operating regime. Even though several investigators have worked on development of these swirl cups, there is a scanty data reported in literature relevant to their design. In the present study, flow behavior in a swirl cup assembled in a confined chamber similar to a gas turbine combustor has been analyzed. Flow analysis has been carried out using ANSYS Fluent and turbulence has been modeled using Realizable k-ϵ model. Six swirl cup configurations have been analyzed; mass flow ratio between primary and secondary swirler and venturi converging area ratio have been varied. The effect of these parameters on downstream flow field has been studied by analyzing the profiles of axial, tangential and radial velocities downstream of swirl cup. The size and shape of the recirculation zone has been analyzed and reported for all configurations. Also, the mass flow recirculated by swirl cup has been estimated and compared amongst the configurations analyzed. Data thus generated is very useful in designing such swirl cups of gas turbine combustors.

Modeling and Computation of Flow in a Passage With 360-Degree Turning and Multiple Airfoils

1993 ◽  
Vol 115 (1) ◽  
pp. 103-108 ◽  
Author(s):  
W. Shyy ◽  
T. C. Vu
Keyword(s):  
Porous Medium ◽  
Global Analysis ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Hydraulic Turbine ◽  
Complex Flow ◽  
The Individual ◽  
Spiral Casing

The spiral casing of a hydraulic turbine is a complex flow device which contains a passage of 360-degree turning and multiple elements of airfoils (the so-called distributor). A three-dimensional flow analysis has been made to predict the flow behavior inside the casing and distributor. The physical model employs a two-level approach, comprising of (1) a global model that adequately accounts for the geometry of the spiral casing but smears out the details of the distributor, and represents the multiple airfoils by a porous medium treatment, and (2) a local model that performs detailed analysis of flow in the distributor region. The global analysis supplies the inlet flow condition for the individual cascade of distributor airfoils, while the distributor analysis yields the information needed for modeling the characteristics of the porous medium. Comparisons of pressure and velocity profiles between measurement and prediction have been made to assess the validity of the present approach. Flow characteristics in the spiral casing are also discussed.

Flow Characteristics of Microscale Porous Media with Varying Porosity and Pore Size

2018 ◽  
Vol 773 ◽  
pp. 225-229
Author(s):  
Jun Sik Lee
Keyword(s):  
Porous Media ◽  
Pressure Drop ◽  
Pore Size ◽  
Gas Turbine ◽  
Flow Behavior ◽  
Fluid Pressure ◽  
Flow Characteristics ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Air Cooling

Sintered porous media are considered to be one of the best candidates to cool high temperature gas turbine components with blades and vanes for next-generation air cooling. The sintered porous media used in this study is made of the stainless steel SUS316L by metal injection molding process. The complex interaction between fluid and the porous medium causes fluid pressure drop when the fluid is forced to flow through the porous surface. In addition, the information on the relation between porosity and pressure drop of the porous media is important to saving the costs of the filter application and cooling process. This research is intended to understand flow characteristics of the porous media with the air fluid movement according to different porosity and pore size for gas turbine application. The experimental data compared with the calculation are examined for different experimental conditions, which indicate flow behavior of erratic and compressible on the microscopic scale porous media.

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