Feature-Section-Criterion for Predicting Lean Blowout and Comparison Research

2013 ◽  
Author(s):  
Zhibo Zhang ◽  
Hongtao Zheng ◽  
Honglei Yang ◽  
Ren Yang ◽  
Qian Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
New Method ◽  
Engineering Applications ◽  
Lean Blowout ◽  
Comparison Research ◽  
Annular Combustor ◽  
Combustion Flow ◽  
Feature Section

Lean blowout (LBO) plays an important role in combustor performance. A new method named Feature-Section-criterion (FSC) for predicting the LBO of annular combustor has been put forward and expounded in this paper. A CFD software FLUENT has been used to simulate the combustion flow field of an annular combustor. The process of blowout and effects of flow split among swirlers and primary holes have been researched by using of FSC. The result shows that the predictions of FSC are in agreement with corresponding experimental data. So this method for predicting lean blowout is reliable and can be used for engineering applications.

A New Method for Numerical Prediction of Lean Blowout in Aero-Engine Combustor

2013 ◽  
Author(s):  
Zhibo Zhang ◽  
Hongtao Zheng ◽  
Zhiming Li ◽  
Yajun Li ◽  
Gang Pan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Flow Velocity ◽  
Air Temperature ◽  
New Method ◽  
Lean Blowout ◽  
Aero Engine ◽  
Annular Combustor ◽  
Combustion Flow ◽  
Feature Section

Lean blowout (LBO) is one of the most important parameters on combustor performance. A new method named Feature-Section-criterion (FSC) for predicting LBO of aero-engine annular combustor has been put forward in the present work. A CFD software FLUENT has been used to simulate the combustion flow field of an annular combustor. The prediction of LBO with FSC has been done in this paper and the effects of flow velocity, air temperature and droplet averaged-diameter on the LBO of aero-engine combustor have been discussed by using of FSC. The results show that the predictions of FSC are in agreement with corresponding experimental data. This showing that this method for predicting lean blowout is reliable and can be used for engineering applications.

Spatial structural characteristics of a combustion flow field in an ethylene-fueled supersonic combustor with a rear-wall-expansion cavity

2020 ◽  
Vol 34 (18) ◽  
pp. 2050208
Author(s):  
Guang-Xin Li ◽  
Ming-Bo Sun ◽  
Yi-Xin Yang ◽  
Tai-Yu Wang ◽  
Yuan Liu
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Heat Release ◽  
Shear Layer ◽  
Structural Characteristics ◽  
Wall Region ◽  
Rear Wall ◽  
Reaction Heat ◽  
Combustion Heat ◽  
Combustion Flow

A hybrid large eddy simulation (LES)/assumed subgrid probability density function (PDF) closure model was employed to investigate the structural characteristics of the combustion flow field in an ethylene-fueled supersonic combustor with a rear-wall-expansion cavity. The wall pressure distribution from numerical simulation was compared with experimental data, and the numerical results are in good agreement with the experimental data. The spatial distribution characteristics of combustion heat release in the flow field are obtained from the simulation results. The reaction heat release zone is mainly distributed in the cavity. The cavity shear layer forms a concentrated reaction zone that produces a large amount of chemical heat release, thus further maintaining local stable combustion and forming a flame base. The front part of the cavity shear layer has the highest temperature in the whole flow field. There is still excess fuel reaching the cavity rear wall and producing a certain intensity of reaction. In addition, a dispersed small flame intermittently forms in the downstream near-wall region. The premixed combustion mode dominates the cavity recirculation zone, while the combustion in the downstream region evidently shows a non-premixed mode.

Numerical Study of a Dump Diffuser Flow Field in a Short Annular Combustor

1985 ◽  
Author(s):  
Hu Zhiben ◽  
Hua Guangshi
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Computer Program ◽  
Steady Flow ◽  
Numerical Study ◽  
Two Dimensional ◽  
Calculation Domain ◽  
Diffuser Flow ◽  
Annular Combustor ◽  
Relaxation Factors

A computer program for solving the two-dimensional steady flow field of the dump diffuser is made based on the streamtube method and SIMPLE (Semi–Implicit Method for Pressure linked Equations) algorithm. Some concrete measures or improvements are developed to treat the irregularly shaped calculation domain, the inlet distribution of k and ε to use the variable relaxation factors. The flow field in a short dump diffuser model with pre–diffuser and blind flame tube is calculated with the program. The calculated results agree well with the experimental data.

Investigation on hydrodynamic forces leading to coarse particle entrainment using Large-Eddy Simulations

2021 ◽  
Author(s):  
Gaston Latessa ◽  
Angela Busse ◽  
Manousos Valyrakis
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Large Scale ◽  
Large Eddy Simulations ◽  
Flow Conditions ◽  
Mean Flow ◽  
Protection Measures ◽  
Practical Applications ◽  
Particle Entrainment ◽  
Large Eddy

<p>The prediction of particle motion in a fluid flow environment presents several challenges from the quantification of the forces exerted by the fluid onto the solids -normally with fluctuating behaviour due to turbulence- and the definition of the potential particle entrainment from these actions. An accurate description of these phenomena has many practical applications in local scour definition and to the design of protection measures.</p><p>In the present work, the actions of different flow conditions on sediment particles is investigated with the aim to translate these effects into particle entrainment identification through analytical solid dynamic equations.</p><p>Large Eddy Simulations (LES) are an increasingly practical tool that provide an accurate representation of both the mean flow field and the large-scale turbulent fluctuations. For the present case, the forces exerted by the flow are integrated over the surface of a stationary particle in the streamwise (drag) and vertical (lift) directions, together with the torques around the particle’s centre of mass. These forces are validated against experimental data under the same bed and flow conditions.</p><p>The forces are then compared against threshold values, obtained through theoretical equations of simple motions such as rolling without sliding. Thus, the frequency of entrainment is related to the different flow conditions in good agreement with results from experimental sediment entrainment research.</p><p>A thorough monitoring of the velocity flow field on several locations is carried out to determine the relationships between velocity time series at several locations around the particle and the forces acting on its surface. These results a relevant to determine ideal locations for flow investigation both in numerical and physical experiments.</p><p>Through numerical experiments, a large number of flow conditions were simulated obtaining a full set of actions over a fixed particle sitting on a smooth bed. These actions were translated into potential particle entrainment events and validated against experimental data. Future work will present the coupling of these LES models with Discrete Element Method (DEM) models to verify the entrainment phenomena entirely from a numerical perspective.</p>

Flow Field and Hot Streak Migration Through a High Pressure Cooled Vanes With Representative Lean Burn Combustor Outflow

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Tommaso Bacci ◽  
Tommaso Lenzi ◽  
Alessio Picchi ◽  
Lorenzo Mazzei ◽  
Bruno Facchini
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Flow Field ◽  
Fuel Injection ◽  
Leading Edge ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Aero Engine ◽  
University Of Florence ◽  
Hot Streak

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover, important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities, and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl, and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together.In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners, and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50 deg, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure, and velocity fields) has been evaluated by means of a five-hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

Three Approaches for Managing Stiffness in Origami-Inspired Mechanisms

2018 ◽  
Author(s):  
Alden Yellowhorse ◽  
Larry L. Howell
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Engineering Applications ◽  
Element Analysis ◽  
Advantages And Disadvantages ◽  
Large Size ◽  
Selection For

Ensuring that deployable mechanisms are sufficiently rigid is a major challenge due to their large size relative to their mass. This paper examines three basic types of stiffener that can be applied to light, origami-inspired structures to manage their stiffness. These stiffeners are modeled analytically to enable prediction and optimization of their behavior. The results obtained from this analysis are compared to results from a finite-element analysis and experimental data. After verifying these models, the advantages and disadvantages of each stiffener type are considered. This comparison will facilitate stiffener selection for future engineering applications.

Blade-Row Interactions in an LP Turbine at Design and Strong Off-Design Operation

2014 ◽  
Author(s):  
Martin Lipfert ◽  
Jan Habermann ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Yavuz Guendogdu
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Three Dimensional ◽  
Suction Side ◽  
Test Facility ◽  
Time Resolved ◽  
Joint Project ◽  
Multi Stage ◽  
Blade Row ◽  
Wake Interactions

In a joint project between the Institute of Aircraft Propulsion Systems (ILA) and MTU Aero Engines a two-stage low pressure turbine is tested at design and strong off-design conditions. The experimental data taken in the altitude test-facility aims to study the effect of positive and negative incidence of the second stator vane. A detailed insight and understanding of the blade row interactions at these regimes is sought. Steady and time-resolved pressure measurements on the airfoil as well as inlet and outlet hot-film traverses at identical Reynolds number are performed for the midspan streamline. The results are compared with unsteady multi-stage CFD predictions. Simulations agree well with the experimental data and allow detailed insights in the time-resolved flow-field. Airfoil pressure field responses are found to increase with positve incidence whereas at negative incidence the magnitude remains unchanged. Different pressure to suction side phasing is observed for the studied regimes. The assessment of unsteady blade forces reveals that changes in unsteady lift are minor compared to changes in axial force components. These increase with increasing positive incidence. The wake-interactions are predominating the blade responses in all regimes. For the positive incidence conditions vane 1 passage vortex fluid is involved in the midspan passage interaction leading to a more distorted three-dimensional flow field.

Small Horizontal Axis Wind Turbine: Analytical Blade Design and Comparison With RANS-Prediction and First Experimental Data

2013 ◽  
Author(s):  
Tom Gerhard ◽  
Michael Sturm ◽  
Thomas H. Carolus
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Wind Turbine ◽  
Horizontal Axis ◽  
Analytical Models ◽  
Power Coefficient ◽  
Analysis Tool ◽  
Computational Domain ◽  
Horizontal Axis Wind Turbine ◽  
Data Set

State-of-the-art wind turbine performance prediction is mainly based on semi-analytical models, incorporating blade element momentum (BEM) analysis and empirical models. Full numerical simulation methods can yield the performance of a wind turbine without empirical assumptions. Inherent difficulties are the large computational domain required to capture all effects of the unbounded ambient flow field and the fact that the boundary layer on the blade may be transitional. A modified turbine design method in terms of the velocity triangles, Euler’s turbine equation and BEM is developed. Lift and drag coefficients are obtained from XFOIL, an open source 2D design and analysis tool for subcritical airfoils. A 3 m diameter horizontal axis wind turbine rotor was designed and manufactured. The flow field is predicted by means of a Reynolds-averaged Navier-Stokes simulation. Two turbulence models were utilized: (i) a standard k-ω-SST model, (ii) a laminar/turbulent transition model. The manufactured turbine is placed on the rooftop of the University of Siegen. Three wind anemometers and wind direction sensors are arranged around the turbine. The torque is derived from electric power and the rotational speed via a calibrated grid-connected generator. The agreement between the analytically and CFD-predicted kinematic quantities up- and downstream of the rotor disc is quite satisfactory. However, the blade section drag to lift ratio and hence the power coefficient vary with the turbulence model chosen. Moreover, the experimentally determined power coefficient is considerably lower as predicted by all methods. However, this conclusion is somewhat preliminary since the existing experimental data set needs to be extended.

scholarly journals Disjoint combinations profiling (DCP): a new method for the prediction of antibody CDR conformation from sequence

2014 ◽  
Author(s):  
Dimitris Nikoloudis ◽  
Jim E. Pitts ◽  
José W. Saldanha
Keyword(s):  
Protein Engineering ◽  
Prediction Accuracy ◽  
Variable Region ◽  
New Method ◽  
Engineering Applications ◽  
Variable Regions ◽  
Blind Prediction ◽  
Novel Method ◽  
Complementarity Determining Regions ◽  
Sequence Rules

The accurate prediction of the conformation of Complementarity-Determining Regions (CDRs) is important in modelling antibodies for protein engineering applications. Specifically, the Canonical paradigm has proved successful in predicting the CDR conformation in antibody variable regions. It relies on canonical templates which detail allowed residues at key positions in the variable region framework or in the CDR itself for 5 of the 6 CDRs. While no templates have as yet been defined for the hypervariable CDR-H3, instead, reliable sequence rules have been devised for predicting the base of the CDR-H3 loop. Here a new method termed Disjoint Combinations Profiling (DCP) is presented, which contributes a considerable advance in the prediction of CDR conformations. This novel method is explained and compared with canonical templates and sequence rules in a 3-way blind prediction. DCP achieved 93% accuracy over 951 blind predictions and showed an improvement in cumulative accuracy compared to predictions with canonical templates or sequence-rules. In addition to its overall improvement in prediction accuracy, it is suggested that DCP is open to better implementations in the future and that it can improve as more antibody structures are deposited in the databank. In contrast, it is argued that canonical templates and sequence rules may have reached their peak.

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