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Article
Publication date: 6 February 2017

Alain Fossi and Alain DeChamplain

Safety improvement and pollutant reduction in many practical combustion systems and especially in aero-gas turbine engines require an adequate understanding of flame…

Abstract

Purpose

Safety improvement and pollutant reduction in many practical combustion systems and especially in aero-gas turbine engines require an adequate understanding of flame ignition and stabilization mechanisms. Improved software and hardware have opened up greater possibilities for translating basic knowledge and the results of experiments into better designs. The present study deals with the large eddy simulation (LES) of an ignition sequence in a conical shaped bluff-body stabilized burner involving a turbulent non-premixed flame. The purpose of this paper is to investigate the impact of spark location on ignition success. Particular attention is paid to the ease of handling of the numerical tool, the computational cost and the accuracy of the results.

Design/methodology/approach

The discrete particle ignition kernel (DPIK) model is used to capture the ignition kernel dynamics in its early stage of growth after the breakdown period. The ignition model is coupled with two combustion models based on the mixture fraction-progress variable formulation. An infinitely fast chemistry assumption is first done, and the turbulent fluctuations of the progress variable are captured with a bimodal probability density function (PDF) in the line of the Bray–Moss–Libby (BML) model. Thereafter, a finite rate chemistry assumption is considered through the flamelet-generated manifold (FGM) method. In these two assumptions, the classical beta-PDF is used to model the temporal fluctuations of the mixture fraction in the turbulent flow. To model subgrid scale stresses and residual scalars fluxes, the wall-adapting local eddy (WALE) and the eddy diffusivity models are, respectively, used under the low-Mach number assumption.

Findings

Numerical results of velocity and mixing fields, as well as the ignition sequences, are validated through a comparison with their experimental counterparts. It is found that by coupling the DPIK model with each of the two combustion models implemented in a LES-based solver, the ignition event is reasonably predicted with further improvements provided by the finite rate chemistry assumption. Finally, the spark locations most likely to lead to a complete ignition of the burner are found to be around the shear layer delimiting the central recirculation zone, owing to the presence of a mixture within flammability limits.

Research limitations/implications

Some discrepancies are found in the radial profiles of the radial velocity and consequently in those of the mixture fraction, owing to a mismatch of the radial velocity at the inlet section of the computational domain. Also, unlike FGM methods, the BML model predicts the overall ignition earlier than suggested by the experiment; this may be related to the overestimation of the reaction rate, especially in the zones such as flame holder wakes which feature high strain rate due to fuel-air mixing.

Practical implications

This work is adding a contribution for ignition modeling, which is a crucial issue in various combustion systems and especially in aircraft engines. The exclusive use of a commercial computational fluid dynamics (CFD) code widely used by combustion system manufacturers allows a direct application of this simulation approach to other configurations while keeping computing costs at an affordable level.

Originality/value

This study provides a robust and simple way to address some ignition issues in various spark ignition-based engines, namely, the optimization of engines ignition with affordable computational costs. Based on the promising results obtained in the current work, it would be relevant to extend this simulation approach to spray combustion that is required for aircraft engines because of storage volume constraints. From this standpoint, the simulation approach formulated in the present work is useful to engineers interested in optimizing the engines ignition at the design stage.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 25 September 2020

Rui Liu, Haocheng Ji and Minxiang Wei

The purpose of this paper is to investigate power performance, economy and hydrocarbons (HC)/carbon monoxide (CO) emissions of diesel fuel on a two-stoke direct injection…

Abstract

Purpose

The purpose of this paper is to investigate power performance, economy and hydrocarbons (HC)/carbon monoxide (CO) emissions of diesel fuel on a two-stoke direct injection (DI) spark ignition (SI) engine.

Design/methodology/approach

Experimental study was carried out on a two-stroke SI diesel-fuelled engine with air-assisted direct injection, whose power performance and HC/CO emissions characteristics under low-load conditions were analysed according to the effects of ignition energy, ignition advance angle (IAA), injection timing angle and excess-air-ratio.

Findings

The results indicate that, for the throttle position of 10%, a large IAA with adequate ignition energy effectively increases the power and decrease the HC emission. The optimal injection timing angle for power and fuel consumption is 60° crank angle (CA) before top dead centre (BTDC). Lean mixture improves the power performance with the HC/CO emissions greatly reduced. At the throttle position of 20%, the optimal IAA is 30°CA BTDC. The adequate ignition energy slightly improves the power output and greatly decreases HC/CO emissions. Advancing the injection timing improves the power and fuel consumption but should not exceed the exhaust port closing timing in case of scavenging losses. Burning stoichiometric mixture achieves maximum power, whereas burning lean mixture obviously reduces the fuel consumption and the HC/CO emissions.

Practical implications

Gasoline has a low flash point, a high-saturated vapour pressure and relatively high volatility, and it is a potential hazard near a naked flame at room temperature, which can create significant security risks for its storage, transport and use. The authors adopt a low volatility diesel fuel for all vehicles and equipment to minimise the number of different devices using various fuels and improve the potential military application safety.

Originality/value

Under low-load conditions, the two stroke port-injected SI engine performance of burning heavy fuels including diesel or kerosene was shown to be worse than those of gasoline. The authors have tried to use the DI method to improve the performance of the diesel-fuelled engine in starting and low-load conditions.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 9 April 2019

Dongmei Zhao, Yifan Xia, Haiwen Ge, Qizhao Lin, Jianfeng Zou and Gaofeng Wang

Ignition process is a critical issue in combustion systems. It is particularly important for reliability and safety prospects of aero-engine. This paper aims to…

Abstract

Purpose

Ignition process is a critical issue in combustion systems. It is particularly important for reliability and safety prospects of aero-engine. This paper aims to numerically investigate the burner-to-burner propagation during ignition process in a full annular multiple-injector combustor and then validate it by comparing with experimental results.

Design/methodology/approach

The annular multiple-injector experimental setup features 16 swirling injectors and two quartz tubes providing optical accesses to high-speed imaging of flames. A Reynolds averaged Navier–Stokes model, adaptive mesh refinement (AMR) and complete San Diego chemistry are used to predict the ignition process.

Findings

The ignition process shows an overall agreement with experiment. The integrated heat release rate of simulation and the integrated light intensity of experiment is also within reasonable agreement. The flow structure and flame propagation dynamics are carefully analyzed. It is found that the flame fronts propagate symmetrically at an early stage and asymmetrically near merging stage. The flame speed slows down before flame merging. Overall, the numerical results show that the present numerical model can reliably predict the flame propagation during the ignition process.

Originality/value

The dedicated AMR method together with detailed chemistry is used for predicting the unsteady ignition procedure in a laboratory-scale annular combustor for the first time. The validation shows satisfying agreements with the experimental investigations. Some details of flow structures are revealed to explain the characteristics of unsteady flame propagations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 25 April 2008

Ibrahim Mohamed Shaluf

This paper aims to provide graduate students, researchers, governmental and independent agencies with an overview on static electricity.

Abstract

Purpose

This paper aims to provide graduate students, researchers, governmental and independent agencies with an overview on static electricity.

Design/methodology/approach

Static electricity has been studied by researchers, academicians, company specialists, governmental and independent agencies. Static electricity incidents have been collected from several sources such as the technical, general articles, internet web sites, and internal reports. The static electricity definition, incidents, hazards, and static electricity prevention have been reviewed. The static electricity incidents have been arranged and classified into fire, and explosions.

Findings

Static electricity can be the cause of problems in many areas of industry. It presents a source of ignition for flammable gases, liquids and powders. It can cause fires and explosions in tankers, aircraft and petrochemical plant and in printing, pharmaceutical, food products and explosives industries.

Originality/value

This paper presents an overview on static electricity, the incidents, and the methods to prevent static electricity generation and accumulation.

Details

Disaster Prevention and Management: An International Journal, vol. 17 no. 2
Type: Research Article
ISSN: 0965-3562

Keywords

Article
Publication date: 1 August 1941

Ernest F. Fiock

A BRIEF discussion of combustion research, which has been in progress for over three hundred years, must be limited to a specific subdivision of the field. For…

Abstract

A BRIEF discussion of combustion research, which has been in progress for over three hundred years, must be limited to a specific subdivision of the field. For presentation before the Society of Automotive Engineers, it is logical that this report should be confined, in a general way, to that phase of combustion research which is concerned with explosions in gases, and particularly with explosions from which, through the medium of the internal combustion engine, usable power may be derived.

Details

Aircraft Engineering and Aerospace Technology, vol. 13 no. 8
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 March 2003

Wijnand R. Rutgers and Ivan de Jong

Sparkers can be used for the production of acoustic pulses as seismic source for sub‐bottom profiling in the sea. A multi‐tip (200‐800 tips) sparker has been developed…

Abstract

Sparkers can be used for the production of acoustic pulses as seismic source for sub‐bottom profiling in the sea. A multi‐tip (200‐800 tips) sparker has been developed, which makes high‐resolution seismic profiling possible in deep water. The characteristics of the multi‐tip sparker system have been measured in a basin in the laboratory using different arrangements of the capacitive energy storage and salinity of the water. A model in Matlab is used to calculate the current waveform in the spark array for different layouts of the power supply.

Details

Sensor Review, vol. 23 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 8 February 2021

Pradeep Uttam Gaikwad, Senthil Gnanamani and Nithya Subramani

The purpose of this paper is to find the pressure and the knocking phenomena. To get the pressure values, the butterworth bandpass filter was used and the potential of…

Abstract

Purpose

The purpose of this paper is to find the pressure and the knocking phenomena. To get the pressure values, the butterworth bandpass filter was used and the potential of knocking was found by using peak-to-peak pressure values and also the species concentration. Cooled exhaust gas recirculation was the method used to minimize the knocking occurrence in the engine. Moreover, the effect of premixed methanol and start of engine (SOI) on knocking were also determined.

Design/methodology/approach

This paper deals with the compression ignition engine to investigate the unfavorable knocking behavior. The tests were carried out with the 3D model of engine fueled with waste cooking oil blended with TiO2. A number of tests were taken to find the pressure variation and the species concentration at eight different locations in the computational model.

Findings

In doing the tests, the positive intended outcome was achieved. From results, it is clear that the SOI and premixed methanol mitigated the knocking process.

Originality/value

The species concentration and pressure in the form of filtered signal were proved to be the ideal methods for evaluating the knocking event in the engine.

Details

Aircraft Engineering and Aerospace Technology, vol. 94 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 January 1952

SPECIFICATION DEF/2101, now published, supersedes C.S. 2463, and covers Oils OMD‐60, OMD‐110, and OMD‐330. These three grades are designed for use in the compression…

Abstract

SPECIFICATION DEF/2101, now published, supersedes C.S. 2463, and covers Oils OMD‐60, OMD‐110, and OMD‐330. These three grades are designed for use in the compression ignition and spark ignition engines of ground equipment operated by the three Services. It covers H.D. oils. The I.Pet. 124/49 test for engine testing is included with some modifications, one of which calls for 0.35 per cent. minimum sulphur content in the fuel instead of 0.40 per cent. maximum. The cetane number of the fuel is modified to 40 to 45, instead of 43 min. and 53 max. No additives must be used to produce a clean fuel. There are other minor modifications. Engine testing in accordance with MIL‐0–2104 (ORD) is also included with several modifications in line with those mentioned above. The price of this Specification is one shilling net.

Details

Industrial Lubrication and Tribology, vol. 4 no. 1
Type: Research Article
ISSN: 0036-8792

Article
Publication date: 18 January 2013

Janusz Grzelka, Karol Cupiał, Michał Pyrc, Adam Dużyński, Michal Gruca, Józef Brzęczek and Tadeusz Zbos

The purpose of this paper is to describe studies of accidental ignition of fuel‐air mixture. Studies were carried out in a laboratory that contains the naturally aspirated…

Abstract

Purpose

The purpose of this paper is to describe studies of accidental ignition of fuel‐air mixture. Studies were carried out in a laboratory that contains the naturally aspirated aircraft engine LYCOMNIG 320B1A IO type used in the EM‐11C Orka aircraft and the intake system to determine its resilience to the effects of accidental ignition and the occurrence of a backfire.

Design/methodology/approach

Tests were performed on a model under extreme conditions (with the intake system closed) and under conditions similar to normal operation using fuels of different combustion rates.

Findings

It was found that the positive pressure caused by such accidental ignition under normal operating conditions did not exceed 0.08 bar and did not pose any hazard of damaging the intake system of the IO‐320B1‐type LYCOMNIG naturally aspirated aircraft engine, as designed by the aircraft manufacturer.

Practical implications

The positive results of the tests of the EM11C Orka aircraft intake system's resistance to flashback and other positive test results for this aircraft have contributed to obtaining the EASA.A.115 Certificate and the EASA.21J.117 Certificate for the Design Unit, and the plane was presented at the AERO – Friedrichshafen 2011 Exhibition.

Originality/value

The paper described how, in the laboratory, simulated extreme operating conditions of the naturally aspirated aircraft engine intake system powered aircraft fuels with different burning speeds (aviation gasoline, hydrogen).

Details

Aircraft Engineering and Aerospace Technology, vol. 85 no. 1
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 30 October 2020

Habib Gürbüz

Spark ignition (SI) engines are used in a wide area in the transportation industry, from road vehicles to piston-prop aircraft. On the other hand, the decrease in reserves…

Abstract

Purpose

Spark ignition (SI) engines are used in a wide area in the transportation industry, from road vehicles to piston-prop aircraft. On the other hand, the decrease in reserves of fossil fuels used in SI engines and the increase in greenhouse gas emissions makes the use of alternative fuels inevitable. In this paper, optimization of in-cylinder combustion and engine performance parameters by intake-charge conditions [i.e. intake-air temperature, injection timing and exhaust gas recirculation (EGR)] in a hydrogen (H2)-fueled small SI engine is performed.

Design/methodology/approach

Experimental studies were performed at a 1,600 rpm engine speed of a single-cylinder, air-cooled engine having a stroke volume of 476.5 cm3, maximum output power of 13 HP and torque of 25 Nm. The hydrogen-fueled SI engine was operated by a lean air-fuel mixture (ϕ = 0.6) under wide-open throttle (WOT) conditions.

Findings

The findings of the paper show that improvements can be achieved in in-cylinder combustion, indicated engine performance, exhaust NOx emissions with optimum intake-air temperature, the start of H2 injection and the ERG rate.

Practical Implications

It has been determined that a 32°C intake-air temperature, 395°C (bTDC) start of H2 injection, and 5%–10% EGR rates are the most suitable values for the examined hydrogen fueled SI engine.

Originality Value

Hydrogen is a usable alternative fuel for SI engines used in a wide area from road vehicles to piston-prop aircraft engines. However, a number of problems remain that limit hydrogen fueled SI engines to some extent, such as backfire, a decrease of engine power, and high NOx emissions. Therefore, it is appropriate to examine the effects of intake-charge conditions on in-cylinder combustion, engine performance, and NOx emissions parameters in a hydrogen fuelled SI engine.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

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