An Experimental and Numerical Investigation of the Aerodynamic Characteristics of a Flameless Combustor

2019 ◽  
Author(s):  
M. P. Huijts ◽  
A. A. V. Perpignan ◽  
A. G. Rao
Keyword(s):  
Flow Field ◽  
Numerical Investigation ◽  
Flow Structure ◽  
Gas Turbines ◽  
Turbulence Models ◽  
Fuel Mixture ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Chamber Length ◽  
Image Velocimetry

Abstract The flameless combustion (FC) regime is a promising technology for gas turbines, as it potentially yields lower NOx emissions while maintaining high combustion efficiencies. However, the application of FC to gas turbines is still challenging as required conditions for its occurrence depend on several factors such as reactants mixing, residence times, heat losses, and chemical time-scales. Since the mixing of the reactants and incoming fresh air-fuel mixture plays an important role in FC, the aerodynamic characteristics of the combustor are instrumental in determining the combustor emission performance. Focusing on the aerodynamic characteristics, this paper is dedicated to the visualization and description of the flow inside a jet-based combustor designed to operate under FC. The cylindrical combustor has a FLOX® burner head with 12 concentrically placed nozzles, while an acrylic cylinder allowed full optical access to the flow field. The investigation was performed for non-reactive flow. Using Particle Image Velocimetry and a Reynolds-averaged Navier-Stokes CFD analysis, the flow was visualized and modelled. The simulations were run with the Standard and Realizable k-ε (SKE and RKE, respectively), as well as a Reynolds Stress turbulence model. The effect of modifying the SKE model C1ε constant was also investigated. In the experimental campaign, the influence of combustion chamber length, nozzle diameter, and jet velocity were investigated with respect to flow structure, recirculation ratios and entrainment behavior. The results show that the flow structure is mainly dependent on nozzle diameters, while the jet momentum is the correct parameter to assess the recirculation impact of a certain jet flow. The numerical investigation shows that the turbulence intensity at the boundaries is an important parameter to accurately simulate the jet spreading. None of the used turbulence models fully represented the flow field. Nonetheless, the SKE model with model C1ε = 1.44 was the best at representing the jets penetration and vortex core positions, and the recirculation ratio values predicted by it were in good agreement.

Numerical Investigation of the Flow in a Coaxial Piping System

2014 ◽  
Author(s):  
Charles Farbos de Luzan ◽  
Yuri Perelstein ◽  
Ephraim Gutmark ◽  
Thomas Frosell ◽  
Frederic Felten
Keyword(s):  
Flow Field ◽  
Turbulence Models ◽  
Field Measurements ◽  
Industrial Applications ◽  
Navier Stokes ◽  
Piping System ◽  
Image Velocimetry ◽  
Rans Models ◽  
Recirculation Zones ◽  
The One

A coaxial piping system (CPS) that involves a transition from a smaller annulus into a larger annulus is investigated to evaluate the generation of vortices and recirculation zones around the transition area. These areas are of interest for industrial applications where erosion within the piping system is a concern. The focus of this work is to evaluate the capabilities of Computational Fluid Dynamics (CFD) using commercial Reynolds-Averaged Navier Stokes (RANS) models to predict the regions and intensity of vortices and recirculation zones. A trusted grid is developed and used to compare turbulence models. The commercial CFD solver Fluent (Ansys Inc., USA) is used to solve the flow governing equations for different CFD numerical formulations, namely the one equation Spalart-Allmaras model, and steady-state RANS with different turbulence models (standard k-epsilon, k-epsilon realizable, k-epsilon RNG, standard k-omega, k-omega SST, and transition SST) [1]. CFD results are compared to time-averaged particle image velocimetry (PIV) measurements. The PIV provides 3D flow field measurements in the outer annulus of the piping system. Velocities in regions of interest were used to compare each model to the PIV results. An RMS comparison of the numerical results to the measured values is used as a quantitative evaluation of each turbulence model being considered. The results provide a useable CFD model for evaluation of the flow field of this flow field and highlights areas of uncertainty in the CFD results.

scholarly journals Manifold reduction techniques for the comparison of crank angle-resolved particle image velocimetry (PIV) data and Reynolds-averaged Navier-Stokes (RANS) simulations in a spark ignition direct injection (SIDI) engine

2021 ◽  
pp. 146808742110131
Author(s):  
Xiaohang Fang ◽  
Li Shen ◽  
Christopher Willman ◽  
Rachel Magnanon ◽  
Giuseppe Virelli ◽  
...  
Keyword(s):  
Flow Field ◽  
Particle Image ◽  
Direct Injection ◽  
Linear Manifold ◽  
Main Flow ◽  
Navier Stokes ◽  
Reduction Techniques ◽  
Image Velocimetry ◽  
Manifold Reduction ◽  
Relevance Index

In this article, different manifold reduction techniques are implemented for the post-processing of Particle Image Velocimetry (PIV) images from a Spark Ignition Direct Injection (SIDI) engine. The methods are proposed to help make a more objective comparison between Reynolds-averaged Navier-Stokes (RANS) simulations and PIV experiments when Cycle-to-Cycle Variations (CCV) are present in the flow field. The two different methods used here are based on Singular Value Decomposition (SVD) principles where Proper Orthogonal Decomposition (POD) and Kernel Principal Component Analysis (KPCA) are used for representing linear and non-linear manifold reduction techniques. To the authors’ best knowledge, this is the first time a non-linear manifold reduction technique, such as KPCA, has ever been used in the study of in-cylinder flow fields. Both qualitative and quantitative studies are given to show the capability of each method in validating the simulation and incorporating CCV for each engine cycle. Traditional Relevance Index (RI) and two other previously developed novel indexes: the Weighted Relevance Index (WRI) and the Weighted Magnitude Index (WMI), are used for the quantitative study. The results indicate that both POD and KPCA show improvements in capturing the main flow field features compared to ensemble-averaged PIV experimental data and single cycle experimental flow fields while capturing CCV. Both methods present similar quantitative accuracy when using the three indexes. However, challenges were highlighted in the POD method for the selection of the number of POD modes needed for a representative reconstruction. When the flow field region presents a Gaussian distribution, the KPCA method is seen to provide a more objective numerical process as the reconstructed flow field will see convergence with an increasing number of modes due to its usage of Gaussian properties. No additional criterion is needed to determine how to reconstruct the main flow field feature. Using KPCA can, therefore, reduce the amount of analysis needed in the process of extracting the main flow field while incorporating CCV.

scholarly journals Numerical Investigation of Influence of Entropy Wave on the Acoustic and Wall Heat Transfer Characteristics of a High-Pressure Turbine Guide Vane

Acoustics ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 524-538
Author(s):  
Keqi Hu ◽  
Yuanqi Fang ◽  
Yao Zheng ◽  
Gaofeng Wang ◽  
Stéphane Moreau
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Gas Turbines ◽  
Guide Vane ◽  
Turbulence Models ◽  
Local Pressure ◽  
Maximum Heat ◽  
Turbine Guide Vane

As an indirect noise source generated in the combustion chamber, entropy waves are widely prevalent in modern gas turbines and aero-engines. In the present work, the influence of entropy waves on the downstream flow field of a turbine guide vane is investigated. The work is mainly based on a well-known experimental configuration called LS89. Two different turbulence models are used in the simulations which are the standard k-ω model and the scale-adaptive simulation (SAS) model. In order to handle the potential transition issue, Menter’s ð-Reθ transition model is coupled with both models. The baseline cases are first simulated with the two different turbulence models without any incoming perturbation. Then one forced case with an entropy wave train set at the turbine inlet at a given frequency and amplitude is simulated. Results show that the downstream maximum Mach number is rising from 0.98 to 1.16, because the entropy waves increase the local temperature of the flow field; also, the torque of the vane varies as the entropy waves go through, the magnitude of the oscillation is 7% of the unforced case. For the wall (both suction and pressure side of the vane) heat transfer, the entropy waves make the maximum heat transfer coefficient nearly twice as the large at the leading edge, while the minimum heat transfer coefficient stays at a low level. As for the averaged normalized heat transfer coefficient, a maximum difference of 30% appears between the baseline case and the forced case. Besides, during the transmission process of entropy waves, the local pressure fluctuates with the wake vortex shedding. The oscillation magnitude of the pressure wave at the throat is found to be enhanced due to the inlet entropy wave by applying the dynamic mode decomposition (DMD) method. Moreover, the transmission coefficient of the entropy waves, and the reflection and transmission coefficients of acoustic waves are calculated.

Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

1996 ◽  
Vol 118 (4) ◽  
pp. 835-843 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Y. Dong
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Complex Flow ◽  
Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stator at several operating conditions. The flow field is found to be highly three dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier–Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

scholarly journals Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1687
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao ◽  
Yang Liu
Keyword(s):  
Flow Field ◽  
Transient Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Compartment Model ◽  
Navier Stokes ◽  
Engine Compartment ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Relevant Calculation

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

Computational Analysis of a Inverted Double-Element Airfoil in Ground Effect

2006 ◽  
Vol 128 (6) ◽  
pp. 1172-1180 ◽  
Author(s):  
Stephen Mahon ◽  
Xin Zhang
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Near Field ◽  
Turbulence Models ◽  
Ground Effect ◽  
Wake Flow ◽  
Navier Stokes ◽  
Main Element ◽  
Ride Height ◽  
Navier Stokes Equations

The flow around an inverted double-element airfoil in ground effect was studied numerically, by solving the Reynolds averaged Navier-Stokes equations. The predictive capabilities of six turbulence models with regards to the surface pressures, wake flow field, and sectional forces were quantified. The realizable k−ε model was found to offer improved predictions of the surface pressures and wake flow field. A number of ride heights were investigated, covering various force regions. The surface pressures, sectional forces, and wake flow field were all modeled accurately and offered improvements over previous numerical investigations. The sectional forces indicated that the main element generated the majority of the downforce, whereas the flap generated the majority of the drag. The near field and far field wake development was investigated and suggestions concerning reduction of the wake thickness were offered. The main element wake was found to greatly contribute to the overall wake thickness with the contribution increasing as the ride height decreased.

scholarly journals NUMERICAL INVESTIGATION OF A TONE NOISE OF THE FAN WITH CASING TREATMENT

2021 ◽  
pp. 24-38
Author(s):  
Yaroslav Druzhinin ◽  
◽  
Viktor Mileshin ◽  
Anton Rossikhin ◽  
◽  
...  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Numerical Investigation ◽  
Significant Influence ◽  
Aerodynamic Characteristics ◽  
Operational Conditions ◽  
Casing Treatment ◽  
Harmonic Method ◽  
Surge Line ◽  
Bypass Ratio

Numerical investigation of influence of a slot-type casing treatment on acoustic and aerodynamic characteristics of the fan of ultra-high bypass ratio turbofan is presented. The investigation was performed using NUMECA FINE/Turbo solver. NLH harmonic method was used to simulate the effect of casing treatment on unsteady flow field in the turbomachine. Two operational conditions were investigated – “sideline” and “approach”. The attention for the first operational condition was paid for aerodynamic characteristics. Significant influence of casing treatment on them was found especially near the surge line. At the “approach” operational conditions the attention was paid for the proper calculation of tone noise. It was shown that the installation of casing treatment leads to decrease of power of tone noise radiated through the inlet. However the power of the tone noise, radiated through the nozzle, and also the overall power of tone noise increase.

Numerical Investigation on the Second Stator Boundary Layer Under Clocking Effects: Comparison of v2f and LCL-Model

2008 ◽  
Author(s):  
Axel Heidecke ◽  
Bernd Stoffel
Keyword(s):  
Boundary Layer ◽  
Numerical Investigation ◽  
Separation Bubble ◽  
Measurement Data ◽  
Turbulence Models ◽  
Boundary Layer Transition ◽  
Navier Stokes ◽  
Layer Transition ◽  
Numerical Work ◽  
Boundary Layer Development

This paper presents the results of a numerical investigation of a 1.5-stage low pressure turbine. The main focus of the numerical work was the prediction of the stator-2 boundary layer development under the influence of the stator stator clocking. The turbine profile used for the examination is a so called high-lift-profile and was designed for a laminar-turbulent transition over a steady separation bubble. The boundary conditions were defined by the 1.5-stage test turbine located at our laboratory, where also the measurement data was derived from. The calculations were conducted with a two-dimensional Navier-Stokes solver using a finite volume discretisation scheme. The higher level turbulence models v′2-f and the LCL-turbulence model, which are capable to predict boundary layer transition were compared with measurement data at midspan.

Validation of Methods for Calculating Hydrogen Combustion in a Supersonic Model Air Flow Using the Experimental Data of Beach — Evans — Schexnayder

2019 ◽  
pp. 36-45
Author(s):  
N.V. Kukshinov ◽  
S.N. Batura ◽  
M.S. Frantsuzov
Keyword(s):  
Chemical Kinetics ◽  
Stokes Equations ◽  
Turbulence Models ◽  
Fuel Mixture ◽  
Navier Stokes ◽  
Detailed Chemical Kinetics ◽  
Navier Stokes Equations ◽  
Kinetic Mechanisms ◽  
Relative Errors ◽  
Detailed Chemical

This paper deals with numerical simulation of combustion of a hydrogen-air mixture in a supersonic flow. The simulation is based on solving the complete system of Navier-Stokes equations with closure using the turbulence model and detailed chemical kinetics. The mixing and combustion of a hydrogen-air fuel mixture is considered in the experimental formulation of Beach-Evans-Schexnayder. The effect of various kinetic mechanisms, turbulence models, TCI models, and boundary conditions on the solution is studied qualitatively and quantitatively. The relative errors of mass concentration of water for control sections are determined, and the methods’ boundaries are shown. Conclusions are drawn on the influence of turbulent mixing mechanisms and chemical kinetics on the combustion of hydrogen.

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