Numerical Investigation on the Effects of Flame Propagation in Rotary Engine Performance With Leakage and Different Recess Shapes Using Three-Dimensional Computational Fluid Dynamics

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Thirumal Valavan Harikrishnan ◽  
Suryanarayana Challa ◽  
Dachapalli Radhakrishna
Keyword(s):  
Combustion Chamber ◽  
Flame Propagation ◽  
Compression Ratio ◽  
Peak Pressure ◽  
Three Dimensional ◽  
Engine Performance ◽  
Front Propagation ◽  
Fuel Mixture ◽  
Experimental Results ◽  
Rotary Engine

This study was carried out with an objective to develop a 3D simulation methodology for rotary engine combustion study and to investigate the effect of recess shapes on flame travel within the rotating combustion chamber and its effects on engine performance. The relative location of spark plugs with respect to the combustion chamber has significant effect on flame travel, affecting the overall engine performance. The computations were carried out with three different recess shapes using iso-octane (C8H18) fuel, and flame front propagation was studied at different widths from spark location. Initially, a detailed leakage study was carried out and the flow fields were compared with available experimental results. The results for first recess with compression ratio 9.1 showed that the flow and vortex formations were similar to that of actual model. The capability of the 3D model to predict the combustion reaction rate precisely as that of practical engine is presented with comparison to experimental results. This study showed that the flame propagation is dominant toward the leading apex of the rotor chamber, and the air/fuel mixture region in the engine midplane, between the two spark plugs, has very low flame propagation compared to the region in the vicinity of spark. The air/fuel mixture in midplane toward the leading apex burns partially and most of the mixture toward the trailing apex is left unburnt. Recommendations have been made for optimal positioning of the spark plugs along the lateral axis of the engine. In the comparison study with different recess shapes, lesser cavity length corresponding to a higher compression ratio (CR) of 9.6 showed faster flame propagation toward leading side. Also, mass trapped in working chamber reduced and developed higher burn rate and peak pressure resulting in better fuel conversion efficiency. Third recess with lesser CR showed reduced burn rates and lower peak pressure.

Comparative Study of Small Scale Soil Barrier Subjected to Air Blast Load by Using AUTODYN 2D and AUTODYN 3D

2015 ◽  
Vol 819 ◽  
pp. 417-422 ◽  
Author(s):  
J. Jestin ◽  
Ali Faisal ◽  
Ahmad Zaidi Ahmad Mujahid ◽  
Othman Mohd Zaid
Keyword(s):  
Peak Pressure ◽  
Three Dimensional ◽  
Experimental Results ◽  
Small Scale ◽  
Complex Geometries ◽  
Front Part ◽  
Barrier Surface ◽  
Different Shapes ◽  
Small Scale Soil

This paper presents the blast loading of small scale soil barrier subjected to surface burst,analysed by using AUTODYN 2D and AUTODYN 3D.Results from the AUTODYN analyses are then compared with published experimental results. Good agreements with published experimental results are obtained for numerical analysis by using AUTODYN 3D for peak pressure at the front part of the barrier. In this case study, AUTODYN 2D numerical analyses provide higher pressure readingsat about 62% and 36% differences as compared with the published experimental results for pressure measurement at the middle front and back of soil barrier surface. The discrepancy of AUTODYN2D results was due to geometric dissimilarity from the actual experimental test. For complex geometries shape of barrier, that involves different shapes and configurations, three dimensional analyses are required to accurately predict the complex reflections and interactions associated with the propagation of the blast wave.

Fast-Burn Combustion Chamber Design for Natural Gas Engines

1998 ◽  
Vol 120 (1) ◽  
pp. 232-236 ◽  
Author(s):  
R. L. Evans ◽  
J. Blaszczyk
Keyword(s):  
Combustion Chamber ◽  
Engine Performance ◽  
Fuel Mixture ◽  
Performance Parameters ◽  
Combustion Chambers ◽  
Natural Gas Engines ◽  
Chamber Design ◽  
Performance And Emissions ◽  
Unburned Hydrocarbons ◽  
Fuel Mixtures

The work presented in this paper compares the performance and emissions of the UBC “Squish-Jet” fast-burn combustion chamber with a baseline bowl-in-piston (BIP) chamber. It was found that the increased turbulence generated in the fastburn combustion chambers resulted in 5 to 10 percent faster burning of the air–fuel mixture compared to a conventional BIP chamber. The faster burning was particularly noticeable when operating with lean air–fuel mixtures. The study was conducted at a 1.7 mm clearance height and 10.2:1 compression ratio. Measurements were made over a range of air–fuel ratios from stoichiometric to the lean limit. At each operating point all engine performance parameters, and emissions of nitrogen oxides, unburned hydrocarbons, and carbon monoxide were recorded. At selected operating points a record of cylinder pressure was obtained and analyzed off-line to determine mass-burn rate in the combustion chamber. Two piston designs were tested at wide-open throttle conditions and 2000 rpm to determine the influence of piston geometry on the performance and emissions parameters. The UBC squish-jet combustion chamber design demonstrates significantly better performance parameters and lower emission levels than the conventional BIP design. Mass-burn fraction calculations showed a significant reduction in the time to burn the first 10 percent of the charge, which takes approximately half of the time to burn from 10 to 90 percent of the charge.

Investigating the Effect of Utilizing New Induction Manifold Designs on the Combustion Characteristics and Emissions of a Direct Injection Diesel Engine

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Mohamed A. Bassiony ◽  
Abdellatif M. Sadiq ◽  
Mohammed T. Gergawy ◽  
Samer F. Ahmed ◽  
Saud A. Ghani
Keyword(s):  
Diesel Engine ◽  
Peak Pressure ◽  
Direct Injection ◽  
Three Dimensional ◽  
Engine Performance ◽  
Combustion Characteristics ◽  
Maximum Pressure ◽  
Performance And Emissions ◽  
Di Diesel Engine ◽  
Dynamics Simulations

New induction manifold designs have been developed in this work to enhance the turbulence intensity and improve the mixing quality inside diesel engine cylinders. These new designs employ a spiral-helical shape with three different helical diameters (1D, 2D, 3D; where D is the inner diameter of the manifold) and three port outlet angles: 0 deg, 30 deg, and 60 deg. The new manifolds have been manufactured using three-dimensional printing technique. Computational fluid dynamics simulations have been conducted to estimate the turbulent kinetic energy (TKE) and the induction swirl generated by these new designs. The combustion characteristics that include the maximum pressure raise rate (dP/dθ) and the peak pressure inside the cylinder have been measured for a direct injection (DI) diesel engine utilizing these new manifold designs. In addition, engine performance and emissions have also been evaluated and compared with those of the normal manifold of the engine. It was found that the new manifolds with 1D helical diameter produce a high TKE and a reasonably strong induction swirl, while the ones with 2D and 3D generate lower TKEs and higher induction swirls than those of 1D. Therefore, dP/dθ and peak pressure were the highest with manifolds 1D, in particular manifold m (D, 30). Moreover, this manifold has provided the lowest fuel consumption with the engine load by about 28% reduction in comparison with the normal manifold. For engine emissions, m (D, 30) manifold has generated the lowest CO, SO2, and smoke emissions compared with the normal and other new manifolds as well, while the NO emission was the highest with this manifold.

Air supply system design of a Diesel–Brayton combined cycle engine

2018 ◽  
Vol 233 (4) ◽  
pp. 545-555
Author(s):  
Yuzhi Jin ◽  
Yuping Qian ◽  
Yangjun Zhang ◽  
Weilin Zhuge
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Operation Mode ◽  
Three Dimensional ◽  
Engine Performance ◽  
Supply System ◽  
Combined Cycle ◽  
Air Supply ◽  
Startup Performance

The Diesel–Brayton combined cycle engine was proposed previously to achieve the goal of lower fuel consumption, higher power density and good startup performance under low-temperature conditions. The prototype engine was designed and tested based on an off-the-shelf gas turbine and a diesel engine. To achieve a more compact and lighter design, the air supply system was designed based on the centrifugal compressor of the gas turbine. In the coupling operation mode aiming to generate the maximum power, a large amount of compressed air must be extracted into the diesel engine. The present paper presents the design methodology of the compact air supply system. The bleeding slot configuration was selected based on a parametric study and proven by systematic experiments. Three-dimensional simulations were conducted to investigate the performance and flow field of the compressor. Backflow appeared in several passages of the axial diffuser caused by air bleeding, which further distorted the air flow in the combustion chamber. Such distortion may cause compressor and combustion instabilities. In the future, the combustion chamber and the axial diffuser must be designed in combination with an air bleeding system to improve the engine performance.

THERMO ACOUSTIC PROCESSES IN LOW EMISSION COMBUSTION CHAMBER OF GAS TURBINE ENGINE CAPACITY 25 MW

2019 ◽  
pp. 86-90
Author(s):  
Sergey Serbin
Keyword(s):  
Mathematical Models ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Three Dimensional ◽  
Fuel Mixture ◽  
Gas Turbine Engine ◽  
Operational Parameters ◽  
Combustion Chambers ◽  
Turbine Engine ◽  
Low Emission

The appliance of modern tools of the computational fluid dynamics for the investigation of the pulsation processes in the combustion chamber caused by the design features of flame tubes and aerodynamic interaction compressor, combustor and turbine is discussed. The aim of the research is to investigate and forecast the non-stationary processes in the gas turbine combustion chambers. The results of the numerical experiments which were carried out using three-dimensional mathematical models in gaseous fuels combustion chambers reflect sufficiently the physical and chemical processes of the unsteady combustion and can be recommended to optimize the geometrical and operational parameters of the low-emission combustion chamber. The appliance of such mathematical models are reasonable for the development of new samples of combustors which operate at the lean air-fuel mixture as well as for the modernization of the existing chambers with the aim to develop the constructive measures aimed at reducing the probability of the occurrence of the pulsation combustion modes. Keywords: gas turbine engine, combustor, turbulent combustion, pulsation combustion, numerical methods, mathematical simulation.

Development of a three-dimensional knock simulation method incorporating a high-accuracy flame propagation model

2005 ◽  
Vol 6 (1) ◽  
pp. 73-83 ◽  
Author(s):  
A Teraji ◽  
T Tsuda ◽  
T Noda ◽  
M Kubo ◽  
T Itoh
Keyword(s):  
Combustion Chamber ◽  
Flame Propagation ◽  
Turbulence Intensity ◽  
Engine Speed ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Propagation Model ◽  
General Tendency ◽  
Flamelet Model ◽  
Flame Kernel

Combustion in internal combustion (IC) engines involves very complicated phenomena (including flame propagation and knock), which are strongly affected by engine speed, load, and turbulence intensity in the combustion chamber. The aim of this study was to develop a flame propagation model and a knock prediction technique applicable to various engine operating conditions, including engine speed and in-cylinder turbulence intensity. A new flame propagation model, the universal coherent flamelet model (UCFM) has been developed that improves the coherent flamelet model (CFM) by considering flame growth both in terms of the turbulent flame kernel and laminar flame kernel. A knock prediction model was developed by implementing the Livengood-Wu integral as the autoignition model in the flame propagation model. The combined model allows evaluation of both where and when autoignition occurs in a real shape combustion chamber. A comparison of the measured and calculated time for the occurrence of knock shows good agreement for various operating conditions. The three-dimensional calculation results indicate the general tendency for the location where autoignition occurs in the combustion chamber and the effect of the spark plug position on the occurrence of knock.

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