scholarly journals Analytical and Numerical Feasibility Analysis of a Contra-Rotary Ramjet Engine

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 163
Author(s):  
Tomasz Laube ◽  
Janusz Piechna
Keyword(s):  
Numerical Simulations ◽  
Stokes Equations ◽  
Analytical Data ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Combustion Model ◽  
Similar Data ◽  
High Rotational Speed ◽  
Jet Engine ◽  
Ramjet Engine

A new idea for a contra-rotary ramjet engine is presented. To define the theoretical limits of the non-typical, contra-rotary ramjet engine configuration, its analytical model was developed. The results obtained from that model and the analytical results were compared with those received from numerical simulations. The main weakness of existing rotary ramjet engine projects is the very high rotational speed of the rotor required for achieving supersonic inlet flow. In this paper, a new idea for a contra-rotary ramjet engine (CORRE) is presented and analyzed. This paper presents the results of analytical analysis and numerical simulations of a jet engine system with two rotors rotating in opposite directions. Contra-rotating rotors generate a supersonic air velocity at the inlet to the compressor at two times slower rotor’s speed. To determine the flow characteristics, combustion process, and engine efficiency of the double-rotor engine, a numerical solution of the average Navier-Stokes equations was used with the k-eps turbulence model and the non-premixed combustion model. The results of numerical simulations of flow and the combustion process inside the contra-rotary jet engine achieving a shockwave compression are shown and compared with similar data for a single-rotor engine design and analytical data. This paper presents only the calculation results of the flow processes and the combustion process, indicating the advantages of the proposed double-rotor design. The results of the numerical analysis were presented on the contours and diagrams of the pressure and flow velocity, temperature distribution, and mass fraction of the fuel.

A Methodology for Steady and Unsteady Full-Engine Simulations

2019 ◽  
Author(s):  
Luigi Romagnosi ◽  
Yingchen Li ◽  
Mohamed Mezine ◽  
Mateus Teixeira ◽  
Stephane Vilmin ◽  
...  
Keyword(s):  
High Speed ◽  
Compressible Flows ◽  
Stokes Equations ◽  
High Reliability ◽  
Combustion Process ◽  
Combustion Model ◽  
Cfd Models ◽  
Flamelet Generated Manifold ◽  
Tabulated Chemistry ◽  
Fully Coupled

Abstract With the increase of computational power, more sophisticated computational methods can be used, larger systems simulated, and complex phenomena predicted more reliably. Nevertheless, up to now, when turbomachinery systems are numerically optimized, each of the components, i.e., the compressor, combustor, and turbine, is simulated separately from the other two. While this approach allows the use of highly dedicated simulation tools, it does not account for the interactions between the different components. With the purpose to meet the future requirements in terms of low emissions, high reliability and efficiency, a novel, highly efficient, fully-coupled, approach based on the Reynolds-Averaged Navier-Stokes equations (RANS) has been developed, enabling a steady or time-accurate simulation of a full aero-engine within a single code. One of the advantages of a steady, fully coupled approach over a steady component-by-component approach, is that the boundary conditions at the interfaces do not need to be guessed. A fully coupled, time-accurate simulation has furthermore the advantage that the effect of the non-uniform temperature distribution at the outlet of the combustor is accounted for in the determination of the thermal field of the turbine. A Smart Interface methodology permits a direct coupling between the different engine components, compressor-combustor-turbine, and allows the Computational Fluid Dynamics (CFD) models to vary between each component within the same code. This allows the user to switch off, for instance, the combustion model in the turbine and compressor blocks. For the simulation of the combustion process, the Flamelet Generated Manifold (FGM) method is applied. While the approach is superior to classical tabulated chemistry approaches and reliably captures finite-rate effects, it is computationally inexpensive since it only requires the solution of a few extra scalars and the look-up of a combustion table. The model has been extended so that high-speed compressible flows can be simulated and the potential effects between the combustor and the adjacent blade rows can be accounted for. The Nonlinear Harmonic (NLH) method is used to model the unsteady interactions between the blade rows as well as the influence of the inhomogeneities at the combustor outlet on the downstream turbine blade rows. Compared to conventional time-accurate RANS simulations (URANS), this method is two to three orders of magnitude faster and makes time-accurate turbomachinery simulations affordable. With the aim of ensuring thermodynamic consistency between the different components of the engine, the same form of the energy equation is solved in all engine elements. Furthermore, the same thermodynamic coefficients, which are used to describe the reacting processes in the combustor, are used for a caloric description of the fluid in the compressor and turbine blocks. The thermodynamic data between the blocks is transferred using the OpenLabs™ module. The developed approach is described in detail and the potential of the novel full-engine methodology is exploited on the KJ66 micro-turbine gas engine case. The results of both the steady and the time-accurate, fully coupled approaches are analyzed and the interaction between the different components of the KJ66 engine discussed.

Analysis of a HSDI Diesel Engine Intake System by Means of Multi-Dimensional Numerical Simulations: Influence of Non Uniform EGR Distribution

2006 ◽  
Author(s):  
Giuseppe Cantore ◽  
Carlo Arturo De Marco ◽  
Luca Montorsi ◽  
Fabrizio Paltrinieri ◽  
Carlo Alberto Rinaldini
Keyword(s):  
Diesel Engine ◽  
Numerical Simulations ◽  
Mutual Influence ◽  
Combustion Process ◽  
Engine Performance ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
3D Analysis ◽  
Intake System ◽  
Hsdi Diesel Engine

In order to comply with stringent pollutant emissions regulations a detailed analysis of the overall engine is required, assessing the mutual influence of its main operating parameters. The present study is focused on the investigation of the intake system under actual working conditions by means of 1D and 3D numerical simulations. Particularly, the effect of EGR distribution on engine performance and pollutants formation has been calculated for a production 6 cylinder HSDI Diesel engine in a EUDC operating point. Firstly a coupled 1D/3D simulation of the entire engine geometry has been carried out to estimate the EGR rate delivered to every cylinder; subsequently the in-cylinder flow field has been evaluated by simulating the intake and compression strokes. Finally the spray and combustion processes have been studied accounting for the real combustion chamber geometry and particularly the pollutants formation has been determined by using a detailed kinetic mechanism combustion model. The 1D/3D analysis highlighted a significant cylinder to cylinder EGR percentage variation affecting remarkably the pollutant emissions formation, as evaluated by the combustion process simulations. A combined use of commercial and in-house modified codes has been adopted.

Numerical Simulations of Highly Preheated Air Combustion in an Industrial Furnace

1998 ◽  
Vol 120 (4) ◽  
pp. 276-284 ◽  
Author(s):  
T. Ishii ◽  
C. Zhang ◽  
S. Sugiyama
Keyword(s):  
Numerical Simulations ◽  
Production Rate ◽  
Fuel Injection ◽  
Velocity Ratio ◽  
Combustion Process ◽  
Moment Closure ◽  
Combustion Model ◽  
Injection Velocity ◽  
Heating Efficiency ◽  
Reheat Furnace

The numerical simulations of reactive turbulent flows and heat transfer in an industrial slab reheat furnace in which the combustion air is highly preheated have been carried out. The influence of the ratio of the air and fuel injection velocities on the NOx production rate in the furnace has also been studied numerically. A moment closure method with the assumed β probability density function (PDF) for mixture fraction was used in the present work to model the turbulent non-premixed combustion process in the furnace. The combustion model was based on the assumption of instantaneous full chemical equilibrium. The turbulence was modeled by the standard k-ε model with a wall function. The numerical simulations have provided complete information on the flow, heat, and mass transfer in the furnace. The results also indicate that a low NOx emission and high heating efficiency can be achieved in the slab reheat furnace by using low NOx regenerative burners. It is found that the air/fuel injection velocity ratio has a strong influence on the NOx production rate in the furnace.

Numerical Simulation of a Ceramic Furnace Burner - Capacity of Turbulent and Radiation Models

2009 ◽  
Vol 283-286 ◽  
pp. 243-249
Author(s):  
Anouar Souid ◽  
Wassim Kriaa ◽  
Hatem Mhiri ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Stokes Equations ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Modern Society ◽  
Navier Stokes ◽  
Combustion Model ◽  
Radiation Model ◽  
Navier Stokes Equations ◽  
Commercial Code ◽  
Furnace Burner

We intend in this work to model an industrial burner replica of the ceramic tunnel furnace of the Ceramics Modern Society (SOMOCER, TUNISIA). This study aims to evaluate the ability of turbulence and radiation models to predict the dynamics and heat transfer fields. The study is conducted by means of numerical simulations in presence of a reactive flow using the commercial code FLUENT. The 3D Navier-Stokes equations and four species transport equations are solved with the eddy-dissipation (ED) combustion model. We use three turbulence models (k- standard, k- RNG, and RSM) and two radiation models (DTRM and DO). The obtained results demonstrate that the k- standard turbulence model is unable to predict the flow characteristics whereas; the k- RNG and RSM models give a satisfying agreement with the experiments. Suitable results are provided by the DTRM radiation model; whereas, those given by the DO model can be improved.

On the Influence of the Combustion Model on the Result of Turbulent Flames Numerical Simulations

2012 ◽  
Author(s):  
Bogdan Gherman ◽  
Florin Gabriel Florean ◽  
Cristian Cârlănescu ◽  
Ionuţ Porumbel
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Stokes Equations ◽  
Reaction Diffusion ◽  
Turbulent Flames ◽  
Reaction Diffusion Equations ◽  
Combustion Model ◽  
One Dimensional ◽  
Turbulent Reactive Flows ◽  
The Impact

The paper is aimed at evaluating the impact of the combustion model on the accuracy of the results of the numerical simulations of turbulent reactive flows. For this, two numerical simulations of the well known Sandia Flame D case are carried out: a three-dimensional RANS integration of the Navier–Stokes equations using the Eddy Dissipation combustion Model (EDM), and a one-dimensional one, where simplified reaction–diffusion equations are numerically integrated over the radial direction, while the axial convection is modeled by empirical laws. The one-dimensional simulation, however, is based on a more physics related combustion model, the Linear Eddy Mixing model, which also controls the radial turbulent mixing and the large scale radial convection. The results of the two numerical simulations are compared to experimental data in the literature, showing a significantly better accuracy of the Linear Eddy Mixing (LEM) numerical simulation.

scholarly journals Sensitivity analysis of nuclear main pump annular casing tongue blend

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401770659 ◽  
Author(s):  
Xiaorui Cheng ◽  
Wenrui Bao ◽  
Li Fu ◽  
Xiaoting Ye
Keyword(s):  
Kinetic Energy ◽  
Numerical Simulations ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Flow Instability ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Simple Algorithm ◽  
Operating Conditions ◽  
Navier Stokes

Based on the Reynolds-averaged Navier–Stokes equations of relative coordinates and the RNG k-ε turbulence model, using our SIMPLE algorithm, we performed numerical simulations for an AP1000 nuclear main pump model with water as the medium. By changing the size of the tongue blend in the annular casing, seven different schemes were designed. Three-dimensional numerical simulations were conducted for the flow within the pump under various settings, and the flow characteristics of the annular casing using different tongue blends were obtained. The results show that for different operating conditions, there is a specific tongue blend that optimizes pump performance. Based on the calculation results, a larger tongue blend leads to a larger flow rate. Off-design conditions caused flow instability, which in turn caused the tongue blend to have a certain impact on the performance of the impeller. However, the performance of the pump was not primarily affected by changes in the impeller performance, but was instead affected by the performance of the annular casing, which was itself affected by tongue blend. When changing the tongue blend, the change in static pressure and total pressure of the annular casing was larger under the condition of 0.6 Qd and was smaller under the conditions of 1.0 Qd and 1.4 Qd. The turbulent kinetic energy in the annular casing changed mainly in the tongue impact zone and outlet diffuser under the condition of 1.0 Qd; furthermore, the turbulent kinetic energy in the whole of the annular casing demonstrated significant changes under the conditions of 0.6 Qd and 1.4 Qd.

Simulation of an Industrial Tangentially Fired Boiler Firing Metallurgical Gases

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
Guangwu Tang ◽  
Bin Wu ◽  
Kurt Johnson ◽  
Albert Kirk ◽  
Chenn Q. Zhou
Keyword(s):  
Electrical Power ◽  
Combustion Process ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Modeling ◽  
Combustion Model ◽  
Steel Mill ◽  
Operation Conditions ◽  
Boiler Operation ◽  
Industrial Boilers

In industrial environments, boiler units are widely used to supply heat and electrical power. At an integrated steel mill, industrial boilers combust a variable mixture of metallurgical gases combined with additional fuels to generate high-pressure superheated steam. Most tangentially fired boilers have experienced water wall tube failures in the combustion zone, which are thought to be caused by some deficiency in the combustion process. The challenge faced in this present process is that there are very limited means to observe the boiler operation. In this study, a three-dimensional computational fluid dynamics (CFD) modeling and simulation of an industrial tangentially fired boiler firing metallurgical gases was conducted. Eddy dissipation combustion model was applied on this multiple fuel combustion process. Simulation results obtained from the developed CFD model were validated by industrial experiments. A quick comparison of the flame shape from the simulation to the actual flame in the boiler showed a good agreement. The flow field and temperature distribution inside the tangentially fired boiler were analyzed under the operation conditions, and a wall water tube overheating problem was observed and directly related to the flow characteristics.

scholarly journals Combustion Optimization for Coal Fired Power Plant Boilers Based on Improved Distributed ELM and Distributed PSO

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1036 ◽  
Author(s):  
Xinying Xu ◽  
Qi Chen ◽  
Mifeng Ren ◽  
Lan Cheng ◽  
Jun Xie
Keyword(s):  
Power Plant ◽  
Combustion Process ◽  
Optimization Method ◽  
Combustion Efficiency ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Nox Emissions ◽  
Coupling Characteristics ◽  
Learning Machine ◽  
Combustion Optimization

Increasing the combustion efficiency of power plant boilers and reducing pollutant emissions are important for energy conservation and environmental protection. The power plant boiler combustion process is a complex multi-input/multi-output system, with a high degree of nonlinearity and strong coupling characteristics. It is necessary to optimize the boiler combustion model by means of artificial intelligence methods. However, the traditional intelligent algorithms cannot deal effectively with the massive and high dimensional power station data. In this paper, a distributed combustion optimization method for boilers is proposed. The MapReduce programming framework is used to parallelize the proposed algorithm model and improve its ability to deal with big data. An improved distributed extreme learning machine is used to establish the combustion system model aiming at boiler combustion efficiency and NOx emission. The distributed particle swarm optimization algorithm based on MapReduce is used to optimize the input parameters of boiler combustion model, and weighted coefficient method is used to solve the multi-objective optimization problem (boiler combustion efficiency and NOx emissions). According to the experimental analysis, the results show that the method can optimize the boiler combustion efficiency and NOx emissions by combining different weight coefficients as needed.

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