Investigation of Turbulent Models for the Flow Field From a Typical Strut-Based Scramjet Combustor

2011 ◽  
Author(s):  
Shi-bin Luo ◽  
Wei Huang ◽  
Hui Qin ◽  
Zhen-guo Wang ◽  
Jun Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Shear Layer ◽  
Flow Fields ◽  
Numerical Results ◽  
Reflected Shock Wave ◽  
Small Scale ◽  
Reacting Flow ◽  
Scramjet Combustor ◽  
Turbulent Models

The two-dimensional coupled implicit RANS equations and three turbulent models have been employed to numerically simulate the nonreacting and reacting flow fields of a typical strut-based scramjet combustor, and the numerical results have been compared with the experimental data. At the same time, three different grid scales have been used to test the grid independence in the numerical simulations, namely the small scale (81,590 nodes), the moderate scale (98,510 nodes) and the large scale (147,470 nodes). The obtained results show that the RNG k-ε model is more suitable to numerically simulate the flow field in the scramjet combustor than the realizable k-ε model and the SST k-ω model, and the numerical results obtained by the moderate and large grid scales show reasonably better agreement with the experimental data. The quasi-diamond wave system is formed in both the nonreacting and reacting flow fields. In the reacting flow field, there are two clear strong shear layers generated between the fuel injection and the supersonic freestream, and at the intersection point between the shear layer and the reflected shock wave, the reaction zone is broader than anywhere else. In the corner formed between the upper surface of the strut and the shear layer, an expansion wave is clearly generated, and another also exists in the symmetrical corner.

A Comparison of Flow Fields Predicted by Various Turbulent Lubrication Models With Existing Measurements

1999 ◽  
Vol 122 (2) ◽  
pp. 475-477 ◽  
Author(s):  
Xiaojing Wang ◽  
Zhiming Zhang ◽  
Meili Sun
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Couette Flow ◽  
Flow Fields ◽  
Countercurrent Flow ◽  
Lubrication Models

Flow field predictions of various turbulent lubrication models are compared with the existing experimental data of turbulent Couette flow and shear-induced countercurrent flow. [S0742-4787(00)00502-6]

Biomass pyrolysis modeling of systems at laboratory scale with experimental validation

2018 ◽  
Vol 28 (2) ◽  
pp. 413-438 ◽  
Author(s):  
Stefano Cordiner ◽  
Alessandro Manni ◽  
Vincenzo Mulone ◽  
Vittorio Rocco
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Fast Pyrolysis ◽  
Experimental System ◽  
High Energy ◽  
Numerical Results ◽  
Small Scale ◽  
Content Type ◽  
Slow Pyrolysis ◽  
Bio Oil

Purpose Thermochemical conversion processes are one of the possible solutions for the flexible production of electric and thermal power from biomass. The pyrolysis degradation process presents, among the others, the interesting features of biofuels and high energy density bio-oil production potential high conversion rate. In this paper, numerical results of a slow batch and continuous fast pyrolyzers, are presented, aiming at validating both a tridimensional computational fluid dynamics-discrete element method (CFD–DEM) and a monodimensional distributed activation energy model (DAEM) represents with data collected in dedicated experiments. The purpose of this paper is then to provide reliable models for industrial scale-up and direct design purposes. Design/methodology/approach The slow pyrolysis experimental system, a batch of small-scale constant-pressure bomb for allothermic conversion processes, is presented. A DEM numerical model has been implemented by means of a modified OpenFOAM solver. The fast pyrolysis experimental system and a lab scale screw reactor designed for biomass fast pyrolysis conversion are also presented along with a 1D numerical model to represent its operation. The model which is developed for continuous stationary feeding conditions and based on a four-parallel reaction chemical framework is presented in detail. Findings The slow pyrolysis numerical results are compared with experimental data in terms of both gaseous species production and reduction of the bed height showing good predictive capabilities. Fast pyrolysis numerical results have been compared to the experimental data obtained from the fast pyrolysis process of spruce wood pellet. The comparison shows that the chemical reaction modeling based on a Gaussian DAEM is capable of giving results in very good agreement with the bio-oil yield evaluated experimentally. Originality/value As general results of the proposed activities, a mixed experimental and numerical approach has demonstrated a very good potential in developing design tools for pyrolysis development.

Numerical Simulation and Experimental Verification of a Vertical Jet in Swirling Cross-Flow

2012 ◽  
Vol 235 ◽  
pp. 90-95
Author(s):  
Shun Li Kou ◽  
Guo Neng Li
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Flow Velocity ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Tunable Laser ◽  
Simulation Method ◽  
Numerical Results ◽  
Cross Flow Velocity ◽  
Vertical Jet

In order to investigate the bending and mixing characteristics in a vertical jet issuing into a swirling cross-flow, large eddy simulation method was employed to simulate the flow field of a jet in swirling cross-flow. Several jet to cross-flow velocity ratios (r=15, 30, 60) were investigated. The numerical results were compared to the experimental data measured from a phase tunable laser and CCD system. The Reynolds number Re based on the characteristic length of the cross-flow tunnel and the jet velocity lies between 22,537 and 90,146. Numerical results showed that the penetration depth of the vertical jet maintains nearly unchanged when the jet to cross-flow velocity ratio is large enough (r>30), which agreed well with the experimental data and was different from the flow field of jet in straight cross-flow. On the other hand, the case of r=60 obtained largest spread width, and the spread width maintains relatively large in a large penetration zone, which is consist with the experimental finding.

Preliminary Numerical Investigation of Effect of Interceptor on Ship Resistance

2011 ◽  
Vol 97-98 ◽  
pp. 1085-1090 ◽  
Author(s):  
Rui Deng ◽  
De Bo Huang ◽  
Guang Li Zhou ◽  
Hua Wei Sun
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Numerical Investigation ◽  
Satisfactory Agreement ◽  
High Speed ◽  
Three Dimensional ◽  
Numerical Results ◽  
Two Dimensional ◽  
Ship Resistance ◽  
The Right

In the present work, the CFD software FLUENT is used to calculate the ship resistance and simulate the flow field around it. Comparison of the numerical results with experimental data of the ship without interceptor shows basically satisfactory agreement in the case of high-speed. In order to get the right parameters of the interceptor for the ship, some two dimensional calculation is taken to study the influence of interceptor with different size. The simulation of the three dimensional vessel with interceptor is also included, and the effect is discussed.

scholarly journals 3D Numerical Modeling of Rigid Inclusion-Improved Soft Soils Under Monotonic and Cyclic Loading—Case of a Small-Scale Laboratory Experiment

2021 ◽  
Vol 11 (4) ◽  
pp. 1426
Author(s):  
Hung Van Pham ◽  
Daniel Dias
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Cyclic Loading ◽  
Rigid Inclusion ◽  
Research Work ◽  
Reinforced Soil ◽  
Numerical Results ◽  
Small Scale ◽  
3D Numerical Modeling ◽  
Soil Arching

This paper is based on small-scale laboratory tests (1:10) of a rigid inclusion-improved soil under normal gravity. A low area improvement ratio (2.4%) under monotonic and cyclic loading was used. 3D numerical calculations are performed to model these tests. The proposed numerical modeling is performed by the finite element method (FEM) using the ABAQUS software. A representative elementary volume model is suggested for reducing the calculation time. A hypoplastic constitutive model (HYP model) is applied for the load transfer platform (LTP). A total of three geometrical configuration cases of the experimental tests are numerically considered including a rigid slab over a mattress of 100 mm on the reinforced soil, a mattress of 100 mm on the reinforced soil, and a rigid slab over a mattress of 50 mm on the reinforced soil. The proposed numerical results are compared to the experimental data and the previous numerical results of Houda. The cyclic response of the systems is shown in terms of soil arching and settlements. The decrease in pile efficacy and the cumulative settlements are exhibited. The HYP model allows to better simulate the soil arching mechanisms inside the LTP than the CYsoil model used in the Houda’s research work. A good concordance between the proposed numerical results and the experimental data was obtained.

Vortical Structures in Pin Fin Arrays for Turbine Cooling Applications

2019 ◽  
Author(s):  
Marcel Otto ◽  
Justin Hodges ◽  
Gaurav Gupta ◽  
Jayanta S. Kapat
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Shear Layer ◽  
Vortex Formation ◽  
Reynolds Numbers ◽  
Numerical Results ◽  
Model Parameters ◽  
Flow Physics ◽  
Pin Fin ◽  
Pin Fin Arrays

Abstract Pin fin arrays are common features in the trailing edge region of turbine blades, and provide both structural integrity and increases in heat removal rates. Aforementioned pins act as fins by increasing the flow-wetted area, while also introducing complex flow structures such as von Kármán vortex shedding and horseshoe vortex systems; both directly affecting the global and local heat transfer characteristics over the endwall. The present study utilizes a wind tunnel to investigate the row to row interactions throughout a pin fin array comprised of four staggered rows, with spanwise and streamwise pitches of 2.5 pin diameters with a focus on the flow field downstream of the first row. The channel height to pin diameter ratio of 2. The Reynolds numbers tested based on pin diameter and local maximum velocity are 10,000 and 30,000. PIV is used as the experimental method of choice for acquiring quantitative flow data to study the flow field and derive high fidelity turbulence data and vortex structures with respect to the effects of the upstream rows on the pin fins downstream; this describes the underlying flow physics that drive the local Nusselt Number distribution on the cooled surface. Also, it was found that the wake structure varies over the two Reynolds Numbers significantly due to increased flow instabilities which promote shear layer separation and vortex formation. Flow acceleration due to neighboring pins confines the vortex formation in spanwise direction. The distribution of turbulent kinetic energy and the contribution of all Reynolds Stress Tensor components is reported. The turbulent scheme in the wake region is particularly anisotropic. The test section pressure drop is in agreement with literature for 30,000 Reynolds Number, but larger for smaller Reynolds Numbers. A thorough RANS simulation of the baseline case was conducted by carefully adjusting the turbulence model parameters to accurately reflect this particular experimental setup. The numerical results are in good agreement with heat transfer results and thus are utilized to further understand the underlying flow physics. However, the shear layer breakdown is underpredicted in numerical results resulting in shielded regions in the wake of the pin with artificially low heat transfer. The findings of the study contribute to better understanding of the underlying flow physics in a pin fin cooled airfoil and assist design engineers in making better internal cooling geometries.

Simulation of Two-Dimensional Scramjet Combustor Reacting Flow Field Using Reynolds Averaged Navier-Stokes WENO Solver

2015 ◽  
Vol 18 (4) ◽  
pp. 1181-1210 ◽  
Author(s):  
Juan-Chen Huang ◽  
Yu-Hsuan Lai ◽  
Jeng-Shan Guo ◽  
Jaw-Yen Yang
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Navier Stokes ◽  
Reacting Flow ◽  
Simulation Tool ◽  
Fuel Injector ◽  
Steady State Condition ◽  
Scramjet Combustor ◽  
Combustion Properties ◽  
Reynolds Averaged Navier Stokes

AbstractThe non-equilibrium chemical reacting combustion flows of a proposed long slender scramjet system were numerically studied by solving the turbulent Reynolds averaged Navier-Stokes (RANS) equations. The Spalart-Allmaras one equation turbulence model is used which produces better results for near wall and boundary layer flow field problems. The lower-upper symmetric Gauss-Seidel implicit scheme, which enables results converge efficiently under steady state condition, is combined with the weighted essentially non-oscillatory (WENO) scheme to yield an accurate simulation tool for scramjet combustion flow field analysis. Using the WENO schemes high-order accuracy and its non-oscillatory solution at flow discontinuities, better resolution of the hypersonic flow problems involving complex shock-shock/shock-boundary layer interactions inside the flow path, can be achieved. Two types of scramjet combustor with cavity-based and strut-based fuel injector were considered as the testing models. The flow characteristics with and without combustion reactions of the two types combustor model were studied with a transient hydrogen/oxygen combustion model. The detailed results of aerodynamic data are obtained and discussed, moreover, the combustion properties of varying the equivalent ratio of hydrogen, including the concentration of reacting species, hydrogen and oxygen, and the reacting products, water, are demonstrated to study the combustion process and performance of the combustor. The comparisons of flow field structures, pressure on wall and velocity profiles between the experimental data and the solutions of the present algorithms, showed qualitatively as well as the quantitatively in good agreement, and validated the adequacy of the present simulation tool for hypersonic scramjet reacting flow analysis.

Parallelized, Automated, Predictive, Imprint Cooling Model for Combustor Liners

2016 ◽  
Author(s):  
Alejandro M. Briones ◽  
Brent A. Rankin ◽  
Scott D. Stouffer ◽  
Timothy J. Erdmann ◽  
David L. Burrus
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Discharge Coefficient ◽  
Numerical Results ◽  
Reacting Flow ◽  
Flow Rates ◽  
Turbulent Flow Field ◽  
The One ◽  
Combustor Liner ◽  
Cooling Model

A novel parallelized, automated, predictive imprint cooling model (PAPRICO) was developed for modeling and simulation of combustor liners using a Reynolds averaged Navier-Stokes (RANS) approach. The methodology involves removing the film and effusion cooling jet geometry from the liner while retaining the cooling hole imprints on the liner. The PAPRICO can operate under two modalities, viz., two-sided and one-sided. For the two-sided PAPRICO model, the imprints are kept on the plenum and combustor sides of the liner. For the one-sided PAPRICO model, the imprints are retained only on the combustor side of the liner and there is no need for a plenum. Consequently, the one-sided PAPRICO significantly reduces the size of the mesh when compared with a mesh that resolves the film and effusion cooling holes. The PAPRICO model neither needs a priori knowledge of the cooling flow rates through various combustor liner regions nor specific mesh partitioning. The PAPRICO model uses the one-dimensional adiabatic, calorifically perfect, total energy equation. The total temperature, total pressure, jet angle, jet orientation, and discharge coefficient are needed to determine the imprint mass flow rate, momentum, enthalpy, turbulent kinetic energy, and eddy dissipation rate. These physical quantities are included in the governing equations as volumetric source terms in cells adjacent to the liner on the combustor side. Additionally, the two-sided PAPRICO model integrates the volumetric sources to calculate their corresponding volumetric sinks in the cells adjacent to the liner on the plenum side. The PAPRICO model user-defined subroutines were written in C programming language and linked to the ANSYS Fluent. A Fluent graphical user interface panel was also developed in Scheme language to effectively and conveniently form effusion cooling regions based on jet angle, jet orientation, pattern, and discharge coefficient. The PAPRICO algorithm automatically identifies and computes the jet area, jet diameter, jet centroid, and jet count per cooling region from an arbitrarily partitioned mesh. Jets with concentric patterns, containing multiple jet orientations, can be conveniently grouped into a single imprint zone. A referee combustor liner was simulated using PAPRICO under non-reacting flow conditions. The PAPRICO results were compared with the non-reacting flow results of a resolved geometry containing 1504 cooling jets (with multiple jet sizes, orientations and angles) and 7 dilution jets. The PAPRICO results were also compared with the non-reacting numerical results of the referee combustor liner with prescribed mass and enthalpy source terms. The numerical results were also compared with experimental measurements of mass flow rates through the referee combustor liner. The numerical results clearly conclude that PAPRICO can qualitatively and quantitatively emulate the local turbulent flow field with only one third of the mesh of that which resolves the effusion cooling jets. The simulations with prescribed mass and enthalpy sources fail to emulate the local turbulent flow field. The PAPRICO model can predict the relative flow rates through the various regions in the liner based on comparisons with measurements.

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.

Sign in / Sign up

Export Citation Format

Share Document