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1

Turbulent Combustion Modeling for Turbo-Jet Combustion Chambers.  

National Technical Information Service (NTIS)

The size of the combustion chamber and the operating conditions chosen are taken into account in developing turbulent combustion models for turbojet engines. Premixed and non premixed conditions are discussed in terms of their integration in turbulence mo...

R. Borghi

1990-01-01

2

Mathematical modeling of an aluminum casting furnace combustion chamber  

Microsoft Academic Search

A mathematical model has been developed for the combustion chambers of aluminum casting furnaces by combining the fluid flow\\u000a code PHOENICS with a zone model for the radiative heat transfer analysis and a simplified flame model. It offers flexibility\\u000a in specifying the size and the combustion and heat transfer characteristics of the furnace. Thus, the model can be used to

T. Bourgeois; R. T. Bui; A. Charette; Y. S. Kocaefe

1989-01-01

3

Optimization of Combustion Chamber for Diesel Engine Using Kriging Model  

Microsoft Academic Search

Diesel engine combustion chamber which reduces exhaust emission has been designed using CFD analysis and optimization techniques. In order to save computational time for design, the Kriging model, one of the response surface models, is adopted here. For a robust exploration, both the estimated function value of the model and its uncertainty are considered at the same time. In the

Shinkyu Jeong; Youichi Minemura; Shigeru Obayashi

2006-01-01

4

Optimization of Combustion Chamber for Diesel Engine Using Kriging Model  

NASA Astrophysics Data System (ADS)

Diesel engine combustion chamber which reduces exhaust emission has been designed using CFD analysis and optimization techniques. In order to save computational time for design, the Kriging model, one of the response surface models, is adopted here. For a robust exploration, both the estimated function value of the model and its uncertainty are considered at the same time. In the present problem, the k-means method is used to limit the number of additional sample points to a reasonable level. Among the additional sample points, two combustion chamber shapes dominate the baseline configuration in terms of all objective functions. Compared with the previous optimization with the evolutionary algorithm, its computational time for design was cut by 95%. The results indicate that the present method is a practical approach for real-world applications.

Jeong, Shinkyu; Minemura, Youichi; Obayashi, Shigeru

5

Flow measurements in a model ramjet secondary combustion chamber  

Microsoft Academic Search

Experimental studies were conducted on a typical secondary combustion chamber of a ramjet to understand the influence of various inlet parameters such as primary nozzle configuration, secondary air injection angle, and flow Reynolds numbers on the secondary combustion chamber (SCC) performance. Cold flow studies were made with air as the flow medium for both primary and secondary jets followed by

Lazar T. Chittilapilly; S. Venkateswaran; P. J. Paul; H. S. Mukunda

1990-01-01

6

Modelling of flow processes in the combustion chamber of IC engine  

Microsoft Academic Search

The increase in charge turbulence in the combustion chamber of the gas engine is one of the effective methods of improving the combustion process. Results of numerical modelling of flow processes in the combustion chamber are presented in the paper. The researches were conducted using KIVA-3V software.

Wojciech Tutak

2009-01-01

7

Combustion stability characteristics of the model chamber with various configurations of triplet impinging-jet injectors  

Microsoft Academic Search

Combustion stability characteristics in actual full-scale combustion chamber of a rocket engine are investigated by experimental\\u000a tests with the model (sub-scale) chamber. The present hot-fire tests adopt the combustion chamber with three configurations\\u000a of triplet impinging-jet injectors such as F-O-O-F, F-O-F, and O-F-O configurations. Combustion stability boundaries are obtained\\u000a and presented by the parameters of combustion-chamber pressure and mixture (oxidizer\\/fuel)

Chae Hoon Sohn; Woo-Seok Seol; Alexander A. Shibanov

2006-01-01

8

Combustion chamber noise suppressor  

Microsoft Academic Search

A combustion chamber is described for a hot fog generating machine comprising a hollow cylindrical combustion chamber shell having a closure plate at one end and outlet means at the opposite end for directing hot combustion gasses to a fogging nozzle, air inlet means disposed adjacent the outlet means, fuel inlet means and ignition means mounted in the closure plate

1986-01-01

9

Combustion chamber construction  

Microsoft Academic Search

A combustion chamber is described for use in gas turbine engines, the chamber comprising: an inlet for receiving air and fuel to be burned; an outlet for expelling products of combustion; high strength structural frame means disposed between the inlet and the outlet for supporting mechanical forces associated with the chamber; liner means cooperating with the frame and defining a

A. P. Sterman; T. G. Wakeman; J. J. Williams

1986-01-01

10

Flow measurements in a model ramjet secondary combustion chamber  

SciTech Connect

Experimental studies were conducted on a typical secondary combustion chamber of a ramjet to understand the influence of various inlet parameters such as primary nozzle configuration, secondary air injection angle, and flow Reynolds numbers on the secondary combustion chamber (SCC) performance. Cold flow studies were made with air as the flow medium for both primary and secondary jets followed by similar studies with hot primary jets. The general flow structure in the SCC obtained from surface oil film technique showed recirculation zones near the head end. The combustor length required for jet mixing was found to be unrelated to recirculation zone length confirmed by selective temperature and total pressure profile measurements. The calculated frictional loss from the momentum balance consideration was found to be small. That significant improvement in mixing can be achieved by a choice of multiple-hole primary nozzle configuration has been demonstrated. 11 refs.

Chittilapilly, L.T.; Venkateswaran, S.; Paul, P.J.; Mukunda, H.S. (ISRO, Vikram Sarabhai Space Centre, Trivandrum (India) Indian Institute of Science, Bangalore (India))

1990-12-01

11

Auxiliary combustion chamber  

SciTech Connect

An auxiliary combustion chamber is described for an internal combustion engine, the chamber comprises: (a) a chamber liner formed of a ceramic material that is an effective thermal insulator, the chamber liner having substantially hemispherical internal and external surfaces; (b) an outer metal member cast around the chamber liner, the outer member including a substantially hemispherical portion contacting the outer surface of the chamber liner and imparting a compressive stress to the chamber liner; the metal member further includes a substantially cylindrical portion contiguous with the open end of the hemispherical portion and extending beyond the chamber liner; the cylindrical portion has an inner surface of a predetermined inside diameter at ambient temperature; and (c) a substantially cup-shaped nozzle portion formed of a heat-resistant ceramic material and having an orifice disposed in the bottom to provide flow communication from a main combustion chamber to the interior of the auxiliary combustion chamber, the nozzle portion includes a substantially cylindrical outer surface having a diameter greater than predetermined inside diameter of cylindrical portion of the metal member; the nozzle portion is shrink-fit within the cylindrical portion of the outer metal member with the cylindrical outer surface of the ceramic nozzle contacting the inner surface of the cylindrical portion of the metal member. The bottom of the nozzle portion is disposed away from the hemispherical portion of the metal member.

Kawamura, M.; Taniguchi, M.

1987-06-30

12

IDENTIFICATION OF AN IDEAL REACTOR MODEL IN A SECONDARY COMBUSTION CHAMBER  

EPA Science Inventory

Tracer analysis was applied to a secondary combustion chamber of a rotary kiln incinerator simulator to develop a computationally inexpensive networked ideal reactor model and allow for the later incorporation of detailed reaction mechanisms. Tracer data from sulfur dioxide trace...

13

Turbulent flow field measurements in a model gas turbine combustion chamber  

Microsoft Academic Search

The results of the investigation of the reactive flow in a scaled-down (?1:3) model of a gas turbine combustion chamber are presented. The lean-premix combustion chamber model was tested at atmospheric pressure; measurements in the reactive flow were taken by using a two-channel fibre-optic laser Doppler anemometer with Al2O3 seeding on the air flow. Measurements cover a wide region of

Daniele Contini; Marco Ruggiero; Giampaolo Manfrida

1998-01-01

14

Internal combustion chamber  

SciTech Connect

In combination with a high-powered reciprocating piston internal combustion engine, an internal combustion cylinder assembly is described comprising: a cylinder head made of weldable material; a cylinder liner for containing and guiding a reciprocating piston of the engine, a coolant jacket adapted to receive a cooling fluid, mounted on and surrounding the cylinder liner, the jacket being attached to the cylinder head and detachably supported by the cylinder liner, and forming a cooling chamber around the cylinder liner; means to supply the cooling fluid to the cooling chamber and to discharge the cooling fluid therefrom.

Schmitz, D.L.

1988-03-08

15

Combustion chamber noise suppressor  

SciTech Connect

A combustion chamber is described for a hot fog generating machine comprising a hollow cylindrical combustion chamber shell having a closure plate at one end and outlet means at the opposite end for directing hot combustion gasses to a fogging nozzle, air inlet means disposed adjacent the outlet means, fuel inlet means and ignition means mounted in the closure plate and liner means disposed concentrically within the cylindrical combustion chamber for controlling the flow of air and combustion gasses within the shell. The liner means includes a liner base having a frustroconical configuration with the smaller diameter end thereof disposed in communication with the outlet means and with the larger diameter end thereof disposed in spaced relation to the shell, circumferentially spaced, longitudinally extending fins extending outwardly from the liner base intermediate the liner base and the shell, a cylindrical liner midsection having circumferentially spaced fins extending outwardly therefrom between the midsection and the shell with the fins supporting the midsection on the larger diameter end of the liner base.

Livingston, A.M.

1986-08-19

16

Acoustoelastic Interaction in Combustion Chambers: Modeling and Experiments  

Microsoft Academic Search

To decrease NOx emissions from combustion systems, lean premixed combustion is used. A disadvantage is the higher sensitivity to combustion instabilities, leading to increased sound pressure levels in the combustor and resulting in an increased excitation of the surrounding structure: the liner. This causes fatigue, which limits the lifetime of the combustor. This paper presents a joint experimental and numerical

R. A. Huls; Kampen van J. F; Hoogt van der P. J. M; J. B. W. Kok; A. de Boer

2008-01-01

17

Effect of preheating on liquid fuel evaporation on combustion in a model combustion chamber  

Microsoft Academic Search

A combustion model for a sprayed liquid fuel is developed, starting from the assumption that combustion of an individual drop is impossible, and the droplets are completely entrained in the moving medium. The model gives the a flame length close to that observed experimentally. It is established that the preheat time of the droplet is roughly the same as its

S. A. Zaitsev; V. R. Kuznetsov; G. M. Kuntsev

1991-01-01

18

Numerical modeling of boundary-layer cooling of rocket engine combustion chambers  

NASA Astrophysics Data System (ADS)

This study investigates boundary-layer cooling of rocket engine combustion chambers by means of numerical modeling. Using computational fluid dynamic methods to model the reacting viscous flow field in rocket combustion chambers, various propellant combinations and chamber geometries are analyzed. Specific propellants are hydrogen-oxygen and methane-oxygen mixtures. Chamber geometries used are the Space Shuttle Main Engine, 5.7 diameter research chamber, and the Apollo/Saturn F-1. Several modifications to existing codes are required to accommodate proposed boundary-layer cooling using fuel as the boundary fluid. This work discusses the mathematical basis for the numerical scheme used and the chemistry models needed to solve the reacting flow field, including specifically the field's boundary layer. Variables considered in the flow field are temperature, pressure, Mach number, species concentration, velocity, density, acoustic velocity, and heat transfer. Using results obtained in the study, a high pressure (Pc > 3000 psi) methane fueled rocket engine is proposed. Included is an analytical estimate of how thrust can be increased, with no loss of performance due to the active fuelfed boundary layer. The author concludes that numerical methods can effectively model the flow processes in boundary-layer cooled combustion chambers, giving designers the requisite information for analyzing rocket engines.

Pitalo, Gerald Alexander

2000-10-01

19

Combustion chamber construction  

SciTech Connect

This patent describes a combustion chamber for use in gas turbine engines is provided with a liner formed of a high temperature material. The liner includes a plurality of annular rings of high temperature material mounted by means of flexible mounting arrangement upon a high strength structural frame. As a result of this mounting arrangement, the liner is substantially isolated from structural forces associated with the combustion chamber, while the frame is substantially isolated from thermal stresses associated with the liner. The individual liner rings may be easily removed for repair or replacement without disassembling the frame and associated components. Furthermore, the decoupling of thermal and structural stresses provides longer life and more dependable operation.

Maclin, H.M.

1989-04-03

20

Combustion chamber construction  

SciTech Connect

A combustion chamber for use in gas turbine engines is provided with a liner formed of a high temperature material. The liner includes a plurality of panels of the material mounted by means of a lost motion mounting arrangement upon a high strength structural frame. As a result of this mounting arrangement, the liner is substantially isolated from structural forces associated with the combustion chamber, while the frame is substantially isolated from thermal stresses associated with the liner. For the purpose of supplying cooling air to the liner panels and frame and cooling air is passed into a plenum to cool the radially outward side of the panels. Transfer means are provided for directing the same air from the plenum to the liner inner surfaces in a cooling film. The liner mounting arrangement disclosed herein is particularly useful with difficult-to-weld liner materials (e.g., oxide dispersion strengthened materials), but its advantages commend its use with other materials also.

Maclin, H.M.

1984-11-06

21

Engine combustion chamber structure  

SciTech Connect

This patent describes a combustion chamber structure comprising an upper wall surface which is shaped like a pent-roof and into which an intake passage opens, a piston having on a head portion thereof a bulged portion conforming to the upper wall surface in shape, a first bowl portion which is formed substantially at the center of the bulged portion and which is substantially semispherical in shape, a pair of second bowl portions which respectively extend on opposite sides of the first bowl portion to the corresponding ends of the bulged portion of the piston along the edge of the bulged portion and are in communication with the first bowl portion, a swirl generating means which is adapted to generate a swirl of intake air in the combustion chamber when the engine load is light, and a spark plug disposed to substantially face the center of the first bowl portion from the upper wall surface; the swirl generating means being adapted to generate the swirl of intake air in a tangential direction in the combustion chamber; and the diameter of the first bowl portion being larger than the width of the second bowl portion.

Tanaka, H.

1988-09-13

22

Modeling of gas dynamics in a pulse combustion chamber to predict initial drying process parameters  

Microsoft Academic Search

A mathematical model of gas-dynamical processes in a pulse combustion chamber for drying of materials is formulated with regard for the second viscosity. Results of numerical solution of the gas-dynamical problem are reported. In particular, it is shown that the time dependences of the gas pressure and velocity represent sinusoidal plots with a phase shift. Introduction of the dissipation term

P. S. Kuts; P. V. Akulich; N. N. Grinchik; C. Strumillo; I. Zbici?ski; E. F. Nogotov

2002-01-01

23

Internal flow-field measurements in a model can-type gas-turbine combustion chamber  

Microsoft Academic Search

LDA measurements of the three mean velocity components and the corresponding turbulence intensities have been made to provide qualitative and quantitative information on the flow-field in a water model of a can-type gas turbine combustion chamber. The combustor geometry comprised a swirl driven primary zone, annulus fed rows of primary and secondary jets and an exit contraction nozzle. Flow visualization

P. Koutmos; J. J. McQuirk; C. Vafidis

1985-01-01

24

Gas turbine combustion chamber arrangement  

Microsoft Academic Search

A gas turbine has a combustion chamber of toroidal configuration that includes separation structure dividing the combustion chamber into an annular primary zone and an annular dilution zone. Injection of compressor discharge air into the primary zone sets up a toroidal recirculation pattern of generally circular cross-sectional configuration. Fuel slinger structure at the inner periphery of the primary zone has

A. M. Heitmann; W. L. Brassert; D. N. Chouinard

1977-01-01

25

Large Eddy Simulations of Diesel Combustion Chambers.  

National Technical Information Service (NTIS)

This report presents findings of a systematic study of turbulence predictions for diesel combustion chambers. Particular topics covered include (1) turbulence models for Reynolds averaged Navier-Stokes solutions, (2) turbulence scale analysis, (3) efficie...

I. B. Celik W. S. Lewellen J. M. Kuhlman E. Amin A. Gel

1999-01-01

26

Swirl chamber type combustion chamber for diesel engine  

Microsoft Academic Search

This patent describes a swirl chamber type combustion chamber for a Diesel engine comprising: a piston head in the chamber defining a concavity which guides the stream of combustion gas injected from the swirl chamber into the main combustion chamber at the top dead center of the piston stroke, the concavity being formed in a substantially triangular configuration with an

K. Hataura; M. Nagahama

1989-01-01

27

Internal combustion engine with rotary combustion chamber  

SciTech Connect

This patent describes an internal combustion engine comprising: a block having at least one cylindrical wall surrounding a piston chamber, piston means located in the piston chamber, means operable to reciprocate the piston means in the chamber, head means mounted on the block covering the chamber. The head means having an air and fuel intake passage, an exhaust gas passage, a rotary valve assembly operatively associated with the head means for controlling the flow of air and fuel into the rotary valve assembly and piston chamber and the flow of exhaust gas from rotary valve assembly and the piston chamber, the head means having a housing with a bore open to the piston chamber accommodating the rotary valve assembly. The valve assembly comprising a cylindrical sleeve located in the bore, the sleeve having an inner surface, an ignition hole, and intake and exhaust ports aligned with the intake passage and exhaust gas passage, spark generating means mounted on the housing operable to generate a spark, rotatable valving means located within the sleeve for controlling the flow of air and fuel into the rotary valve assembly and piston chamber and the flow of exhaust gases out of the rotary valve assembly and piston chamber, the rotatable valving means having a valving combustion chamber open to the piston chamber and the inner surface of the sleeve, the rotatable valving means having a valve body. The valving combustion chamber having an inner portion located in the valve body, the valve body having an outer surface spaced from the inner surface of the sleeve segment seal means mounted on the valve body.

Hansen, C.N.; Cross, P.C.

1988-09-27

28

FEM Approximation of Internal Combustion Chambers for Knock Investigations  

Microsoft Academic Search

The resonances of SI engine combustion chambers are slightly excited during normal combustion but strongly excited by knock. In order to avoid knocking combustions extensive knowledge about knock and its effects is necessary. In this paper the combustion chamber of a serial production engine is modeled by finite elements. Modal analyses are performed in order to gain information about the

Sönke Carstens-Behrens; Mark Urlaub; Johann F. Böhme; Jürgen Förster; Franz Raichle; Robert Bosch

29

Evaporation and ignition of droplets in combustion chambers modeling and simulation  

NASA Astrophysics Data System (ADS)

Computer simulation of liquid fuel jet injection into heated atmosphere of combustion chamber, mixture formation, ignition and combustion need adequate modeling of evaporation, which is extremely important for the curved surfaces in the presence of strong heat and mass diffusion fluxes. Combustion of most widely spread hydrocarbon fuels takes place in a gas-phase regime. Thus, evaporation of fuel from the surface of droplets turns to be one of the limiting factors of the process as well. The problems of fuel droplets atomization, evaporation being the key factors for heterogeneous reacting mixtures, the non-equilibrium effects in droplets atomization and phase transitions will be taken into account in describing thermal and mechanical interaction of droplets with streaming flows. In the present paper processes of non-equilibrium evaporation of small droplets will be discussed. As it was shown before, accounting for non-equilibrium effects in evaporation for many types of widely used liquids is crucial for droplet diameters less than 100 ?m, while the surface tension effects essentially manifest only for droplets below 0.1 ?m. Investigating the behavior of individual droplets in a heated air flow allowed to distinguish two scenarios for droplet heating and evaporation. Small droplets undergo successively heating, then cooling due to heat losses for evaporation, and then rapid heating till the end of their lifetime. Larger droplets could directly be heated up to a critical temperature and then evaporate rapidly. Droplet atomization interferes the heating, evaporation and combustion scenario. The scenario of fuel spray injection and self-ignition in a heated air inside combustion chamber has three characteristic stages. At first stage of jet injection droplets evaporate very rapidly thus cooling the gas at injection point, the liquid jet is very short and changes for a vapor jet. At second stage liquid jet is becoming longer, because evaporation rate decreases due to decrease of temperature. But combustion of fuel vapor begins which brings to increase of heat flux to droplets and accelerates evaporation. The length of the liquid jet decreases again and remains constant slightly oscillating.

Betelin, V. B.; Smirnov, N. N.; Nikitin, V. F.; Dushin, V. R.; Kushnirenko, A. G.; Nerchenko, V. A.

2012-01-01

30

Modeling of Solid Waste Flow and Mixing on the Traveling Grate of a Waste-to- energy Combustion Chamber  

Microsoft Academic Search

Mixing of the highly non-homogeneous municipal solid wastes (MSW) on the traveling grate of mass-burn combustion chambers assists the combustion process in waste-to-energy (WTE) facilities. A matrix-based Markov chain model was developed to simulate particle flow and mixing as the solid waste particles travel over a reverse acting Martin grate. The model was used to project the pathway of a

MASATO NAKAMURA; N. J. THEMELIS

31

Open-chamber combustion study  

NASA Astrophysics Data System (ADS)

The test program was undertaken to research trade-offs between engine design and operational parameters on open-chamber, premixed spark-ignited gas engines, with a primary focus on combustion effects. This included combustion chamber designs which are conceptually diametrically opposed -- a high squish design typical of diesel engines and a virtually quiescent design. The reader should note that these data are somewhat abstract compared to conventional engines, because the Labeco test engine has exceptionally high friction and the lean-burn data were run unboosted.

Meyers, D. P.; Meyer, R. C.

1994-04-01

32

Coal gasification combustion chamber structure  

US Patent & Trademark Office Database

A combustion chamber for powdered coal and the like having a refractory lined floor with an exit throat at the bottom. The throat is shaped approximately in accordance with the ratios employed in a contraction cone of a wind tunnel to produce a monotonic increase in flow therethrough in order to avoid any clogging by liquid slag and fly ash.

Barot; Devendra T. (W. Covina, CA)

1986-03-04

33

Combustion Chamber Wall Temperature Measurement and Modeling During Transient HCCI Operation  

Microsoft Academic Search

In this paper the combustion chamber wall temper- ature was measured by the use of thermographic phosphor. The temperature was monitored over a large time window covering a load transient. Wall temperature measurement provide helpful information in all engines. This temperature is for example needed when calculating heat losses to the walls. Most important is however the effect of the

Carl Wilhelmsson; Bengt Johansson; Gustaf S

2005-01-01

34

Gas turbine combustion chamber with air scoops  

Microsoft Academic Search

This patent describes a gas turbine combustion chamber. It comprises: means for admission of fuel to the upstream end thereof and discharge of hot gases from the downstream end thereof, and a combustion chamber wall, having an outer surface, with apertures therethrough, and air scoops provided through the apertures to direct air into the combustion chamber.

S. E. Mumford; J. P. Smed

1989-01-01

35

Modeling of heat conduction within chamber walls for multidimensional internal combustion engine simulations  

Microsoft Academic Search

A two-dimensional (axisymmetric) transient heat conduction in components computer program (HCC) was successfully developed for predicting engine combustion chamber wall temperatures. The alternating direction explicit (ADE) Saul'yev method, an explicit, unconditionally stable finite difference method, was used in the code. Special treatments for the head gasket and the piston-liner air gap, the piston movement, and a grid transformation for describing

Yong Liu; R. D. Reitz

1998-01-01

36

IMAGING OF VAPOR\\/LIQUID DISTRIBUTIONS OF SPLIT-INJECTED DIESEL SPRAYS IN A TWO-DIMENSIONAL MODEL COMBUSTION CHAMBER  

Microsoft Academic Search

The ultraviolet-visible laser absorption-scattering (LAS) technique was extended to simultaneous imaging of two-dimensional vapor\\/liquid mass distributions in a nonaxisymmetric evaporating diesel spray such as that injected into a two-dimensional model combustion chamber of direct-injection diesel engines. The main error for vapor measurement is incurred by the temperature dependence of molar absorption coefficients (TDMAC) of the test fuel. Thus, selecting a

YUYIN ZHANG; KEIYA NISHIDA

2004-01-01

37

Sub-combustion chamber of an internal combustion engine  

Microsoft Academic Search

In a cylinder head in an internal combustion engine having a cylinder body to which the cylinder head is installed, with a gasket placed therebetween, the cylinder head is described including a pre-combustion chamber having a cylindrical portion for receiving a ceramic hot plug; and a ceramic hot plug disposed in the cylindrical portion of the pre-combustion chamber. The improvement

Toeda

1987-01-01

38

Development of global mixing, combustion, and ignition models for quiescent chamber direct-injection diesel engines  

Microsoft Academic Search

A large scale mixing and combustion model has been developed and studied through testing of two separate direct injection diesel engines. As a corollary, a shear layer ignition model was also developed for estimating the effects of key engine-related parameters on autoignition. Both models were developed for eventual inclusion into an engine cycle simulation for studying the effect of various

Peter Joseph Schihl

1998-01-01

39

Structure of combustion chamber in diesel engine  

Microsoft Academic Search

This patent describes a combustion chamber structure in a diesel engine of a direct injection type having a cylinder block, a cylinder head disposed above the cylinder block, a piston fitted in a cylinder of the cylinder block, a combustion chamber which is formed as a recess in a top part of the piston and whose upper surface is covered

T. Moriyasu; J. Isomoto; T. Nakagami; H. Takahashi; T. Maeda

1988-01-01

40

Stratified-combustion type internal combustion engine with pre-combustion-chamber  

Microsoft Academic Search

A stratified-combustion type internal combustion engine has a rich fuel-air mixture passage and an air passage both open into the main combustion chamber. A pre-combustion chamber is located adjacent to the main combustion chamber and has a connecting port to the main combustion chamber adjacent to the opening of the rich fuel-air mixture passage. The rich fuel-air mixture is supplied

Goto

1976-01-01

41

Method of regulating combustion in the combustion chambers of an internal combustion engine  

SciTech Connect

A method is proposed for regulating the combustion of operating mixtures in the combustion chambers of internal combustion engines. The course of the light intensity of the light resulting from combustion in the combustion chamber is detected and evaluated over the course of combustion; reference control variables derived therefrom are formed for use by subsequently disposed closed-loop control devices of the engine.

Burkel, R.; Eckert, K.; Franke, H.; Linder, E.; Maurer, H.; Moser, W.; Muller, K.; Peter, C.; Rieger, F.

1983-05-03

42

Advanced technology application for combustion chamber concepts  

Microsoft Academic Search

NASA-Marshall is engaged in the development of an Advanced Main Combustion Chamber under the aegis of the Earth-to-Orbit Propulsion Technology Program. AMCC is to be a robust and highly reliable combustion-chamber prototype costing one-third as much as current designs of comparable performance; it will be associated with a reduction of fabrication time by one-half. Attention is presently given to the

Kathy S. Tygielski

1992-01-01

43

Combustion chamber layout for modern Otto engines  

SciTech Connect

Since the most efficient way to improve fuel economy in the part-load range is to increase the compression ratio, emphasis is placed on combustion chambers allowing high compression ratios combined with low octane requirements. According to Porsche experience, many demands can be met in the simplest manner by locating the combustion chamber in the piston crown. This configuration offers various advantages over its counterpart installed in the cylinder head. 24 refs.

Gruden, D.O.

1981-10-01

44

Sub-combustion chamber of an internal combustion engine  

SciTech Connect

In a cylinder head in an internal combustion engine having a cylinder body to which the cylinder head is installed, with a gasket placed therebetween, the cylinder head is described including a pre-combustion chamber having a cylindrical portion for receiving a ceramic hot plug; and a ceramic hot plug disposed in the cylindrical portion of the pre-combustion chamber. The improvement comprises: an annular shoulder in the pre-combustion chamber, an annular elastic member disposed between the annular shoulder and the upper end of the ceramic hot plug and compressed therebetween; the ceramic hot plug being shaped to conform to the cylindrical portion of the pre-combustion chamber so that a small clearance is provided between the ceramic hot plug and the peripheral wall of the pre-combustion chamber; and means for preventing the ceramic hot plug from dropping out of the cylindrical portion of the pre-combustion chamber prior to installation of the cylinder head on the cylinder body.

Toeda, S.

1987-12-22

45

Investigation of the effect of inlet port on the flow in a combustion chamber using multidimensional modeling  

SciTech Connect

The computational fluid dynamics simulation program KIVA is augmented with a k-{epsilon} turbulence model and enhanced geometric capabilities. It is applied to the cause of flow in an inlet port and a chamber with a moving value in order to investigate the effect of inlet flow on the prevailing aerodynamic conditions in the cylinder. The needed initial and time-varying boundary conditions at the upstream section of the intake port are obtained from a one-dimensional acoustic model of the complete single cylinder engine. The three-dimensional flow domain includes on intake port, a combustion chamber and a moving valve. An internal dynamic rezoning procedure is presented and incorporated in the flow code, which ensures an adequate I,J, K-structured hexahedral mesh when the boundaries of the computation domain are severely distorted, as in the case with a moving valve. Flow computation is carried out from induction TDC to BDC. The resulting velocity and residual burned gas mass fraction fields are then examined and effects due to the geometry of the port and chamber are discussed.

Taghavi, R.; Dupont, A. (Direction des Etudes, Regie Nationale des Usines Renault, 92508 Rueil Malmaison Cedex (FR))

1989-07-01

46

Numerical Simulation on Forced Swirl Combustion Chamber in Diesel Engine  

Microsoft Academic Search

A concept of forced swirl combustion chamber in diesel engine is proposed in this paper. It can be used to enhance the intensity of swirl flow in the cylinder and accelerate the rate of air-fuel mixture process by designing the special structure in the combustion chamber. This new type of forced swirl combustion chamber includes double swirl combustion chamber that

Shang Yong; Liu Fu-shui; Li Xiang-rong

2011-01-01

47

Numerical Simulation on Forced Swirl Combustion Chamber in Diesel Engine  

Microsoft Academic Search

A concept of forced swirl combustion chamber in diesel engine is proposed in this paper. It can be used to enhance the intensity of swirl flow in the cylinder and accelerate the rate of air-fuel mixture process by designing the special structure in the combustion chamber. This new type of forced swirl combustion chamber includes double swirl combustion chamber that

Shang Yong; Liu Fu-shui; Li Xiang-rong

2010-01-01

48

Solid Fuel Combustion Chamber. Tenth Progress Report, Ninth Phase, July-December 1986.  

National Technical Information Service (NTIS)

Progress in developing a combustion chamber to study flow and combustion processes in solid fuel grains is outlined. An analytical study of laminar channel flows; computational modeling of flow and combustion, employing algebraic finite element methods; c...

H. Wittenberg P. A. O. G. Korting C. W. M. Vandergeld J. B. Vos T. Wijchers

1987-01-01

49

Internal combustion engine squish jet combustion chamber  

SciTech Connect

This patent describes a internal combustion engine block having a piston and cylinder head, one of which has: (a) a substantially cylindrical bowl opening into the face thereof; (b) a pair of squish jet passages having respective inlets communicating with the face thereof, and respective, transversely spaced, outlets directed substantially tangentially into the bowl, the outlet of a first one of the pair being directed upwardly, and the outlet of second one of the pair being directed downwardly from a position above the outlet of the first one, so that a counter-rotating, bilevel swirl can be produced in the bowl by the squish jet outlets.

Evans, R.L.

1986-02-25

50

The effect of turbulence model variation on flame propagation in a particular 4-valve engine combustion chamber  

NASA Astrophysics Data System (ADS)

In this paper some initial results concerning the evolution of flame propagation in 4-valve engines with tilted valves were presented. Results were obtained by dint of multidimensional modeling of reactive flows in arbitrary geometry with moving boundaries. During induction fluid flow pattern was characterized with organized tumble motion followed by small but clearly legible deterioration in the vicinity of BDC. During compression the fluid flow pattern is entirely three-dimensional and fully controlled by vortex motion located in the central part of the chamber. The effect of turbulence model variation on flame propagation was tackled as well. Namely, some results obtained with eddy-viscosity model i.e. standard k-? model were compared with results obtained with k-?-f model of turbulence in domain of 4-valve engine in-cylinder flow. Some interesting results emerged rendering impetus for further quest in the near future. In the case of combustion all differences ensuing from turbulence model variation, encountered in the case of non-reactive flow were annihilated entirely. Namely the interplay between fluid flow pattern and flame propagation is invariant as regards both turbulence models applied.

Jovanovic, Z.; Masonicic, Z.

2012-11-01

51

Heterogeneous Catalysis in the Diesel Combustion Chamber  

Microsoft Academic Search

Results have been reported recently suggesting that the use of a platinum-coated combustion chamber would significantly reduce gaseous and particulate emissions in a diesel engine. To examine these claims, a single-cylinder version of a conventional automotive diesel engine was tested with and without a platinum coating. For all conditions tested, application of the coating resulted in no significant changes in

DONALD C. SIEGLA; STEVEN L PLEE

1982-01-01

52

30 CFR 56.7807 - Flushing the combustion chamber.  

Code of Federal Regulations, 2013 CFR

...Piercing § 56.7807 Flushing the combustion chamber. The combustion chamber of a jet drill stem which has been sitting unoperated in a drill hole shall be flushed with a suitable solvent after the stem is pulled...

2013-07-01

53

Internal chamber modeling of a solid rocket motor: Effects of coupled structural and acoustic oscillations on combustion  

NASA Astrophysics Data System (ADS)

This paper outlines modeling considerations for the internal ballistics of solid rocket motors. The simulation model consists of three coupled physical components, including the combined propellant and motor structure, the core fluid flow and the propellant combustion. A coupling component is also employed to control the fluid structure combustion interaction during the simulations. The results of simulating a motor firing illustrate the coupled effects of the structural and acoustic oscillations with the combustion model. Comparisons of the predicted results with experimental test results indicate a good correlation exists, providing support for the present simulation model.

Montesano, John; Behdinan, Kamran; Greatrix, David R.; Fawaz, Zouheir

2008-03-01

54

Evaluation of multi-dimensional flux models for radiative transfer in cylindrical combustion chambers  

NASA Astrophysics Data System (ADS)

Four flux-type models for radiative heat transfer in cylindrical configurations were applied to the prediction of radiative flux density and source term of a cylindrical enclosure problem based on data reported previously on a pilot-scale experimental combustor with steep temperature gradients. The models, which are Schuster-Hamaker type four-flux model derived by Lockwood and Spalding, two Schuster-Schwarzschild type four-flux models derived by Siddall and Selcuk and Richter and Quack and spherical harmonics approximation, were evaluated from the viewpoint of predictive accuracy by comparing their predictions with exact solutions produced previously. The comparisons showed that spherical harmonics approximation produces more accurate results than the other models with respect to the radiative energy source term and that the four-flux models of Lockwood and Spalding and Siddall and Selcuk for isotropic radiation field are more accurate with respect to the prediction of radiative flux density to the side wall.

Selcuk, Nevin

1993-02-01

55

Research on the Ignition-Chamber GDI Engine Combustion System  

NASA Astrophysics Data System (ADS)

The ignition-chamber GDI engine combustion system and its fuel injection strategy were presented and studied by multi-dimensional fluid dynamic (CFD) code and experiment. The CFD research result shows that the ignition-chamber combustion system and its fuel injection strategy can ensure that there is flammable mixture with appropriate concentration distribution near the spark plug to enhance the ignition reliability. The performance of the GDI engine with the ignition-chamber combustion system was investigated basing on the existing experiment condition. The result shows that the ignition-chamber combustion system has the potential of decreasing emissions and enhancing the combustion speed and stability.

Fu, Lei; Ishima, Tsuneaki; Long, Wu-Qiang; Tian, Jiang-Ping

56

Prediction of temperature front in a gas turbine combustion chamber  

Microsoft Academic Search

Numerical computation has been applied to investigate the temperature field in a gas turbine combustion chamber. The simulation assumed that pressure imbalance conditions of air flow between primary and secondary inlets occur. The combustion chamber under study is part of a 70MW gas turbine from an operating combined cycle power plant. The combustion was simulated with normal fuel–air flow rate

F. Z. Sierra; J. Kubiak; G. González; G. Urquiza

2005-01-01

57

A novel approach to predict the stability limits of combustion chambers with large eddy simulation  

NASA Astrophysics Data System (ADS)

Lean premixed combustion, which allows for reducing the production of thermal NOx, is prone to combustion instabilities. There is an extensive research to develop a reduced physical model, which allows — without time-consuming measurements — to calculate the resonance characteristics of a combustion system consisting of Helmholtz resonator type components (burner plenum, combustion chamber). For the formulation of this model numerical investigations by means of compressible Large Eddy Simulation (LES) were carried out. In these investigations the flow in the combustion chamber is isotherm, non-reacting and excited with a sinusoidal mass flow rate. Firstly a combustion chamber as a single resonator subsequently a coupled system of a burner plenum and a combustion chamber were investigated. In this paper the results of additional investigations of the single resonator are presented. The flow in the combustion chamber was investigated without excitation at the inlet. It was detected, that the mass flow rate at the outlet cross section is pulsating once the flow in the chamber is turbulent. The fast Fourier transform of the signal showed that the dominant mode is at the resonance frequency of the combustion chamber. This result sheds light on a very important source of self-excited combustion instabilities. Furthermore the LES can provide not only the damping ratio for the analytical model but the eigenfrequency of the resonator also.

Pritz, B.; Magagnato, F.; Gabi, M.

2010-06-01

58

A new approach to cooled combustion chambers: The 40K formed platelet chamber  

Microsoft Academic Search

Regeneratively cooled combustion chambers constructed with formed platelet liners have many benefits over chambers with conventionally machined liners. The formed platelet liner offers increased heat transfer efficiency, which can increase cycle life and enhance wall compatibility. A combustion chamber of the 40,000 lb thrust size has been fabricated and tested with a formed platelet liner to demonstrate this superior heat

David E. Janke; William A. Hayes

1992-01-01

59

Formation of soot particulates in the combustion chamber of a precombustion chamber type diesel engine  

Microsoft Academic Search

To clarify the formation processes of soot particulates in the combustion chamber, we sampled the gas during combustion in a precombustion chamber and a main chamber using an electromagnetic sampling valve, and made a gas analysis by gas chromatography, examined the soot concentration, and size distribution and dispersion of soot particulates with a transmission electron microscope. The following results were

Y. Fujiwara; S. Fukazawa; S. Tosaka; T. Murayama

1984-01-01

60

Secondary Combustion in a Dual-Chamber Woodstove.  

National Technical Information Service (NTIS)

The paper discusses laboratory tests of a modified, popular dual-chamber woodstove to determine its ability to reduce emissions. In dual-chamber stoves, the primary chamber is for fuel volatilization, and the secondary chamber is for combustion. The origi...

G. A. Spolek R. E. Hall J. H. Wasser

1988-01-01

61

Fast-burn combustion chamber design for natural gas engines  

Microsoft Academic Search

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% faster burning of the air-fuel mixture compared to a conventional BIP chamber. The faster burning was particularly noticeable

R. L. Evans; J. Blaszczyk

1998-01-01

62

Two-dimensional combustion chamber analysis of Direct Injection Diesel  

Microsoft Academic Search

Re-entrant bowls for high compression ratio heavy-duty turbocharged DI Diesel have been studied by the utilization of a two-dimensional axisymmetric model of the air motion and spray formation inside the cylinder. The trend of the air motion and spray pattern obtained by changing combustion chamber parameters are compared with the trend of the engine performance like smoke, fuel consumption, gaseous

C. Bassoli; G. Biaggini; G. Bodritti; G. M. Cornetti

1984-01-01

63

Ignition combustion pre-chamber for internal combustion engines with constant stoichiometric air-fuel mixture at ignition  

Microsoft Academic Search

This patent describes an internal combustion engine including at least one combustion chamber and a pre-chamber in fluid communication with the combustion chamber, a method of providing combustion within the combustion chamber. It comprises charging the combustion chamber with a first mixture of air and fuel having a lean ratio of air-to-fuel; charging the pre-chamber with a further mixture of

1992-01-01

64

Plasma arc heated secondary combustion chamber  

SciTech Connect

This paper describes a secondary combustion chamber (SCC) for hazardous waste treatment systems that uses a plasma arc torch as the heat source. Developed under a cooperative research and development agreement (CRADA) between Retech, Inc. and Lawrence Livermore National Laboratory (LLNL), the unit is intended primarily to handle the off-gas from a Plasma Arc Centrifugal Treatment (PACT) system. ft is designed to heat the effluent gas which may contain volatile organic compounds, and maintain the gas temperature above 1000 C for two seconds or more. The benefits of using a plasma arc gas heater are described in comparison to a conventional fossil fuel heated SCC. Thermal design considerations are discussed. Analysis and experimental results are presented to show the effectiveness in destroying hazardous compounds and reducing the total volume of gaseous emissions.

Haun, R.; Paulson, B.; Schlienger, M. [Retech, Inc. (United States); Goerz, D.; Kerns, J.; Vernazza, J. [Lawrence Livermore National Lab., CA (United States)

1995-02-01

65

30 CFR 57.7807 - Flushing the combustion chamber.  

Code of Federal Regulations, 2013 CFR

...Piercing-Surface Only § 57.7807 Flushing the combustion chamber. The combustion chamber of a jet drill stem which has been sitting unoperated in a drill hole shall be flushed with a suitable solvent after the stem is pulled...

2013-07-01

66

Structure of divided combustion chamber for diesel engine  

Microsoft Academic Search

A structure is described defining a divided combustion chamber of a diesel engine consisting of: an upper ceramic member having a substantially hemispherical head and a lower ceramic member having an injection port, the lower ceramic member meeting with the upper ceramic member at an interface to form the divided combustion chamber therein, the upper ceramic member including at least

T. Morita; Wakasa; Y. Ogawa; T. Ogasawara

1986-01-01

67

Three cycle engine with varying combustion chamber volume  

Microsoft Academic Search

A piston type internal combustion engine of novel three cycle variety, in which the intake and compression functions are divorced from the combustion cylinder entirely and are carried out by a separate high pressure compressor; with a high pressure charging cycle, a power cycle and an exhaust cycle carried out in the combustion chamber in a positive manner. The gas

1985-01-01

68

Optimization of combustion chamber geometry for stoichiometric diesel combustion using a micro genetic algorithm  

Microsoft Academic Search

This paper describes the optimization of combustion chamber geometry and engine operating conditions for stoichiometric diesel combustion, targeting lower gross indicated specific fuel consumption. The KIVA code, coupled with a micro genetic algorithm population of nine for each generation was used. The optimization variables were composed of ten variables related to the combustion chamber geometry and engine operating conditions. In

Sung Wook Park

2010-01-01

69

Elimination of Intermediate-Frequency Combustion Instability in the Fastrac Engine Thrust Chamber.  

National Technical Information Service (NTIS)

A series of tests were conducted to measure the combustion performance of the Fastrac engine thrust chamber. The thrust chamber exhibited benign, yet marginally unstable combustion. The marginally unstable combustion was characterized by chamber pressure ...

M. Rocker T. E. Nesman

2001-01-01

70

Four-sensor hot-wire probe measurements of the isothermal flow in a model combustion chamber at different levels of swirl  

SciTech Connect

Measurements of the isothermal flowfield in a model combustion chamber at three different levels of swirl were carried out with a four-sensor hot-wire measurement technique. The new four-sensor hot-wire probe allows the measurement of all three components of the instantaneous velocity vector simultaneously at high data rates. The three mean velocity components and all six Reynolds stress components are subsequently calculated from an appropriate number of instantaneous-velocity measurements. The four-sensor measurement technique is described. The main feature of the flowfields measured is the existence of two distinct regions: a supercritical region in which disturbances do not influence the upstream flow and a subcritical region in which disturbances have a strong up stream influence. The transition from the supercritical flow at the inlet of the combustion chamber to the subcritical flow is associated with vortex breakdown and the formation for recirculation zones. Measurements of the Reynolds stress components are consistent with the mean velocity measurements. 21 refs.

Doebbeling, K.; Lenze, B.; Leuckel, W. (Karlsruhe, Universitaet, (Germany))

1992-05-01

71

Effect of Insulated Combustion Chamber Surfaces on Direct-Injected Diesel Engine Performance, Emissions, and Combustion.  

National Technical Information Service (NTIS)

The combustion chamber of a single-cylinder, direct-injected diesel engine was insulated with ceramic coatings to determine the effect of low heat rejection (LHR) operation on engine performance, emissions, and combustion. In comparison to the baseline co...

D. W. Dickey S. Vinyard R. Keribar

1988-01-01

72

Combustion Tests with Pulverized Fuels in a Cyclone Combustion Chamber.  

National Technical Information Service (NTIS)

The objective with this project has been to establish combustion conditions and characterize material handling, milling and parameters as combustibility, ashmelting, combustion efficiency and emission index, for refined and pulverized fuels from wood, pea...

L. Eriksson

1983-01-01

73

Combustion chamber and thermal vapor stream producing apparatus and method  

DOEpatents

A new and improved method and apparatus for burning a hydrocarbon fuel for producing a high pressure thermal vapor stream comprising steam and combustion gases for injecting into a subterranean formation for the recovery of liquefiable minerals therefrom, wherein a high pressure combustion chamber having multiple refractory lined combustion zones of varying diameters is provided for burning a hydrocarbon fuel and pressurized air in predetermined ratios injected into the chamber for producing hot combustion gases essentially free of oxidizing components and solid carbonaceous particles. The combustion zones are formed by zones of increasing diameters up a final zone of decreasing diameter to provide expansion zones which cause turbulence through controlled thorough mixing of the air and fuel to facilitate complete combustion. The high pressure air and fuel is injected into the first of the multiple zones where ignition occurs with a portion of the air injected at or near the point of ignition to further provide turbulence and more complete combustion.

Sperry, John S. (Houston, TX); Krajicek, Richard W. (Sugar Land, TX); Cradeur, Robert R. (Spring, TX)

1978-01-01

74

A new combustion chamber for fast-burn applications  

SciTech Connect

A new combustion chamber design is proposed in which it is possible to control the scale and intensity of turbulence generated just prior to ignition. A single cylinder engine has been fitted with the new chamber, and measurements of the turbulence field with a hot-wire anemometer are presented. The chamber design has been compared to a conventional bowl-in-piston design under both motoring and fired operation. Hot-wire measurements showed an increase in turbulence intensity of 50% and a reduction in the length scale of turbulence compared to the conventional chamber. Cylinder pressure measurements indicated that the mass-burn rate is increased with the new chamber, particularly during the early stage of combustion. During operation at 1140 rpm with the new chamber, peak cylinder pressure was 4% higher and occurred 3/sup 0/ earlier than for the conventional chamber.

Evans, R.L.; Cameron, C.

1986-01-01

75

Study of convective heat transfer in gas turbine combustion chambers  

Microsoft Academic Search

A detailed investigation of the effect of swirler angle, stabilizing angle and flow rate upon the flow pattern, intensity of turbulence and heat transfer in cold combustion chambers is presented. The results indicate that a central recirculation flow is formed upstream in case of small swirl and along the whole chamber in case of high swirl. This recirculation is shown

M. M. Elkotb; M. M. Hilal; J. A. J. Wahham

1982-01-01

76

A new combustion chamber for fast-burn applications  

Microsoft Academic Search

A new combustion chamber design is proposed in which it is possible to control the scale and intensity of turbulence generated just prior to ignition. A single cylinder engine has been fitted with the new chamber, and measurements of the turbulence field with a hot-wire anemometer are presented. The chamber design has been compared to a conventional bowl-in-piston design under

R. L. Evans; C. Cameron

1986-01-01

77

Fuel combustion test in constant volume combustion chamber with built-in adaptor  

Microsoft Academic Search

Combustion tests of pre-mixture of methane and air in constant volume combustion chamber (CVCC) have been carried out by means\\u000a of flame propagation photo and gas pressure measurement, the effects of CVCC body temperature, intake pressure of pre-mixture\\u000a of methane and air, equivalence ratio and location of the built-in adaptor have been investigated. The whole combustion chamber\\u000a can be divided

HongGuang Zhang; XiaoLei Bai; DongSoo Jeong; GyuBack Cho; SuJin Choi; JinSoo Lee

2010-01-01

78

Mathematical modeling of heat transfer processes of coal waste combustion in a chamber of automated energy generating complex  

NASA Astrophysics Data System (ADS)

The automated energy generating complex allows obtaining heat energy from waste coal-water slurry fuel (WCF) that is a mixture of fine coal particles from coal enrichment wastes with water. The mixture is blown into the swirl chamber under the pressure through the special sprayers. The received heat energy is used in different ways. One of the important issues is to estimate the heat losses through the walls of this chamber. In this paper we solved the boundary problem of mathematical physics to estimate the temperature fields in the walls of the swirl chamber. The obtained solution allows us to estimate the heat losses through the walls of the swirl chamber. The task of the mathematical physics has been solved by a numerical finite-difference method. The method for solving this problem can be used in the calculation of temperature fields and evaluation of heat losses in other thermal power units.

Mochalov, Sergey P.; Kalashnikov, Sergey N.; Mochalov, Pavel S.; Song, Guolin; Tang, Guoyi

2013-04-01

79

Water flow visualisation of a ramrocket combustion chamber  

NASA Astrophysics Data System (ADS)

Flow within the combustion chamber of a ramrocket has been investigated using water flow visualization with air bubbles as tracers. Configurations with four axisymmetric intakes entering the combustion chamber at either 45 or 90 deg have been considered. A region of stable recirculatory flow has been identified at the head end of the combustion chamber and estimates have been obtained of the amount flowing through the recirculation region. Based on this information fuel jets have been designed which it is believed will aid ignition, secure flame stability, and improve combustion efficiency. The interaction between fuel jets and the recirculatory air flow has been tentatively investigated on flow visualization tests using jets of colored water.

Boszko, P. J.; Owen, G. S.

1987-06-01

80

Parameters of a supersonic combustion chamber with organization of combustion at the flame front  

SciTech Connect

In some engineering problems, it is necessary to burn fuel in the combustion chamber with supersonic flow. As a rule, the scheme of organization of the process in such a chamber presupposes a separate accompanying feed of fuel and oxidant in which combustion of fuel takes place in a diffusion flame front. In this article we give theoretical results of investigation of a supersonic combustion chamber in which combustion of the fuel mixture takes place in a oblique flame front stabilized by an external source (analogous to the subsonic combustion chambers of ramjets). The possibility of the existence of such an oblique flame front in a supersonic flow of fuel mixture was previously proved experimentally.

Solokhin, E.L.; Mironenko, V.A.; Ivanov, V.I.

1985-10-25

81

Fast-burn combustion chamber design for natural gas engines  

SciTech Connect

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% 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% of the charge, which takes approximately half of the time to burn from 10 to 90% of the charge.

Evans, R.L.; Blaszczyk, J. [Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Mechanical Engineering

1998-01-01

82

Combustion Chamber Design for a Lean-Burn SI Engine  

Microsoft Academic Search

A combustion chamber designed to increase the burning rate of lean\\u000d\\u000a\\u0009air-fuel mixtures is described. The chamber utilizes squish motion\\u000d\\u000a\\u0009to generate a series of jets which significantly increase the turbulence\\u000d\\u000a\\u0009levels in the chamber during the early phase of combustion. The fuel\\u000d\\u000a\\u0009economy and exhaust emissions resulting from the new chamber design\\u000d\\u000a\\u0009are compared to a conventional bowl-in- piston

R. L. Evans

1992-01-01

83

Corrosion fatigue causes failure of gas turbine combustion chamber  

SciTech Connect

Plates in the combustion chamber case of a gas turbine made of welded alloy 617 (UNS NO6617) and alloy Nimonic 75 (UNS N06075) failed by complete circumferential fracturing at the matrix-welding interface in the UNS N06075 plate. Fatigue cracks were first initiated at the outer subsurface within the intergranularly cracked coarse grains adjacent to the weld and then propagated because of combustion vibration during start-up operation conditions.

Elshawesh, F.; Elhoud, A.; Elmendelsi, T. [Petroleum Research Center, Tripoli (Libyan Arab Jamahiriya); Elwaer, A. [General Electricity Co., Tripoli (Libyan Arab Jamahiriya). Planning and Project Dept.

1997-07-01

84

Numerical simulation of the 3D unsteady turbulent flow in a combustion chamber  

NASA Astrophysics Data System (ADS)

The influence of turbulence models on the 3D unsteady flow in a combustion chamber with a central bluff body is analyzed. Three different turbulence models are used ( realizable k-?, Reynolds Stress Model and Large Eddy Simulation) and a comparison is made on the evolution of the velocity field over time. The numerical simulation of the gas flow in the combustion chamber was performed using FLUENT 6.3 software and the computational geometry, consisting of a structured mesh with 810,000 cells, was built using the pre-processor GAMBIT 2.4. The extent of the recirculation region behind the bluff body was determined for each turbulence model.

Stuparu, Adrian; Holotescu, Sorin

2011-06-01

85

Thermodynamic analysis of a divided combustion chamber diesel engine  

Microsoft Academic Search

A thermodynamic analysis of a naturally aspirated, four-stroke, diesel engine, with a precombustion chamber under firing conditions\\u000a is presented. Special attention is given in setting-up the equations expressing the work, flow and heat transfer processes\\u000a during the open and closed part of the cycle, as well as the combustion processes in the two chambers, taking into account\\u000a their interaction. For

Dimitrios A. Kouremenos; Constantine D. Rakopoulos; Dimitrios Hountalas

1988-01-01

86

Effect of combustion chamber configuration on in-cylinder air motion and combustion characteristics of D. I. diesel engine  

Microsoft Academic Search

A new combustion system for a light duty D.I. diesel engine was developed and introduced. The combustion chamber, which was used in the combustion system, has 4 concaves on the periphery of the inner wall and was called HMMS-III. This combustion chamber realized better fuel consumption and lower smoke level over a wide speed range. In this study, in order

M. Shimoda; M. Shigemori; S. Tsuruoka

1985-01-01

87

Piston/Combustion Chamber Configurations for Enhancec CI Engine Performance.  

National Technical Information Service (NTIS)

Piston face (104, 204, 304) and combustion chamber (18) designs for use particularly in HSDI (high speed direct injection) diesel engines include an open bowl (108 208, 308) characterized by a large face perimeter region (106, 206, 306) on the piston face...

D. D. Wickman R. D. Reitz

2003-01-01

88

Structure of divided combustion chamber for diesel engine  

Microsoft Academic Search

A structure is described defining a divided combustion chamber of a Diesel engine, comprising: an upper ceramic member having a substantially hemispherical head with a substantially hemispherical inner and outer surface and a lower ceramic member with an inner and an outer surface and having an injection port. The lower ceramic member cooperates with the upper ceramic member to form

T. Morita; A. Wakasa; Y. Ogawa; T. Ogasawara

1987-01-01

89

Launch Vehicle with Combustible Polyethylene Case Gasification Chamber Design Basis  

NASA Astrophysics Data System (ADS)

A single-stage launch vehicle equipped with a combustible tank shell of polyethylene and a moving propulsion plant is proposed. The propulsion plant is composed of a chamber for the gasification of the shell, a compressor of pyrolysed polyethylene and a magnetic powder obturator. It is shown that the “dental” structure of the gasification chamber is necessary to achieve the necessary contact area with the polyethylene shell. This conclusion is drawn from consideration of the thermo- physical properties of polyethylene, calculating quasisteady temperature field in the gasification chamber, estimating gasification rate of polyethylene, launch vehicle shortening rate and area of gasification. Experimental determination of the gasification rate is described. The gasification chamber specific mass as well as the propulsion plant weight-to-thrust ratio are estimated under some assumptions concerning the obturator and compressor. Combustible launch vehicles are compared with conventional launch vehicles taking into consideration their payload mass ratios. Combustible launchers are preferable as small launchers for micro and nano satellites. Reusable versions of such launchers seem suitable if polyethylene tank shells filled with metal or metal hydride fine dusts are used.

Yemets, V.

90

Numerical simulation of the effects of combustion chamber geometry on nonroad diesel engine performance  

Microsoft Academic Search

Combustion chamber geometry is very important for the performance of diesel engine, especially for the nonroad diesel engine with low fuel injection pressure. To decrease the experimental work, the CAE technique, such as computational fluid dynamics (CFD), was used to design the combustion chamber of a nonroad diesel engine. In order to investigate the effects of combustion chamber geometry on

Luo Maji; Xiang Liangshan; Li Xiong

2011-01-01

91

Explosion-induced combustion of hydrocarbon clouds in a chamber  

SciTech Connect

The interaction of the detonation of a solid HE-charge with a non-premixed cloud of hydro-carbon fuel in a chamber was studied in laboratory experiments. Soap bubbles filled with a flammable gas were subjected to the blast wave created by the detonation of PETN-charges (0.2 g < mass < 0.5 g). The dynamics of the combustion system were investigated by means of high-speed photography and measurement of the quasi-static chamber pressure.

Neuwald, P; Reichenbach, H; Kuhl, A L

2001-02-06

92

Combustion of liquid fuel in the counter-swirled jets of a gas turbine plant annular combustion chamber  

Microsoft Academic Search

Tests were carried out on an annular combustion chamber rig with a stabilizer of the type used in the GTN-25 gas turbine plant to determine the feasibility of burning a liquid fuel (diesel fuel, GOST 4749-73) in a combustion chamber of this type. Very high performance was obtained for a number of important characteristics of the microflame combustion process in

A. G. Tumanovskii; N. N. Semichastnyi; K. Iu. Sokolov

1986-01-01

93

CAD systems in the production of diesel-engine pistons with a complex combustion chamber  

Microsoft Academic Search

The use of the Kompas CAD system in preparing for the production of diesel-engine pistons with a complex (lobed) combustion\\u000a chamber is considered. An algorithm for the construction of a three-dimensional model is presented.

N. K. Sanaev; A. V. Makhin; F. A. Sal’nitskii

2009-01-01

94

Corrosion fatigue causes failure of gas turbine combustion chamber  

Microsoft Academic Search

Plates in the combustion chamber case of a gas turbine made of welded alloy 617 (UNS NO6617) and alloy Nimonic 75 (UNS N06075) failed by complete circumferential fracturing at the matrix-welding interface in the UNS N06075 plate. Fatigue cracks were first initiated at the outer subsurface within the intergranularly cracked coarse grains adjacent to the weld and then propagated because

F. Elshawesh; A. Elhoud; T. Elmendelsi; A. Elwaer

1997-01-01

95

Spray and Combustion Characteristics of Butanol-Biodiesel-Diesel in a Constant Volume Combustion Chamber  

Microsoft Academic Search

The spray and combustion characteristics of ternary blends of butanol-biodiesel-diesel fuel were experimentally investigated in a constant volume combustion chamber under various ambient temperatures. The blends were mixed in three different volumetric ratios and the biofuels additive is lower than 20% in volume. The results indicate that the spray tip penetration reduced with the increase of ambient temperature and n-butanol

Yu Liu; Haifeng Liu; Ming Huo; Chia-fon F. Lee; Jun Li

2012-01-01

96

Self-oscillations of an unstable fuel combustion in the combustion chamber of a liquid-propellant rocket engine  

NASA Astrophysics Data System (ADS)

The form of the self-oscillations of a vibrating combustion of a fuel in the combustion chamber of a liquidpropellant rocket engine, caused by the fuel-combustion lag and the heat release, was determined. The character of change in these self-oscillations with increase in the time of the fuel-combustion lag was investigated.

Gotsulenko, V. V.; Gotsulenko, V. N.

2013-01-01

97

Effect of combustion chamber shape on air flow field in a D. I. diesel engine  

Microsoft Academic Search

The behaviour of two combustion chambers, a toroidal and a turbulent one, has been compared. The engine performance in terms of imep and exhaust emissions were measured. Laser Doppler Anemometry technique was used to characterize the fluids dynamic aspect of combustion system. The axial asymmetry introduced in combustion chamber shape causes strong differences in the air flow field at the

C. Bertoli; F. E. Corcione; G. Police; G. Valentino

1987-01-01

98

The Design and Manufacture of a 6 Inch Diameter Ablative Combustion Chamber.  

National Technical Information Service (NTIS)

A 6 in. diameter ablative combustion chamber has been designed for use in evaluation tests on rocket engine components. This combustion chamber was designed for operation at 1000 psia chamber pressure with the propellant combination N2O4 and 50% N2H4 - 50...

W. Q. Walker

1965-01-01

99

An expert system concept for diagnosis and monitoring of gas turbine combustion chambers  

Microsoft Academic Search

In this paper, the main principles of operation, the conceptual design and the development of an expert system for fault diagnosis and monitoring of gas turbine combustion chambers are presented. The concept of the gas turbine chamber expert system is based on the monitoring of the spatial and temporal distribution of the heat flux inside the combustion chamber and the

N. H. Afgan; M. G. Carvalho; P. A. Pilavachi; A. Tourlidakis; G. G. Olkhonski; N. Martins

2006-01-01

100

72. VISITOR'S CENTER, MODEL OF BOILER CHAMBER, AUXILIARY CHAMBER, REACTOR ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

72. VISITOR'S CENTER, MODEL OF BOILER CHAMBER, AUXILIARY CHAMBER, REACTOR AND CANAL (LOCATION T) - Shippingport Atomic Power Station, On Ohio River, 25 miles Northwest of Pittsburgh, Shippingport, Beaver County, PA

101

Three dimensional modelling of combustion in a prechamber diesel engine  

Microsoft Academic Search

Three dimensional modelling appears to be a good way to analyze the influence of the major parameters involved in the diesel combustion process. The computer code KIVA was modified and improved in order to be applicable to very complex combustion chamber shapes. A new mesh generator was used and coupled to KIVA. Modelling the diesel combustion required the implementation of

Pinchon

1989-01-01

102

Comparison of LES, RANS and experiments in an aeronautical gas turbine combustion chamber  

Microsoft Academic Search

Although Large Eddy Simulations (LES) have demonstrated their potential in simple academic combustion chambers, their application to real gas turbine chambers requires specific developments and validations. In this study, three specific aspects of such chambers are discussed: multiple inlets, multi-perforated plates and film cooling. LES are used in an industry-like chamber and results are compared with predictions provided by Reynolds

G. Boudier; L. Y. M. Gicquel; T. Poinsot; D. Bissières; C. Bérat

2007-01-01

103

Effects of radiation heat transfer space non-uniformity of combustion chamber components on in-cylinder soot emission formation in diesel engine  

Microsoft Academic Search

Combustion chamber components (cylinder head-cylinder liner-piston assembly-fuel film) were treated as a coupled body. Based\\u000a on the three-dimensional numerical simulation of heat transfer of the coupled body, the multi-dimensional simulation computation\\u000a coupling flow and solid on working process and combustion chamber components of internal combustion engine was performed using\\u000a Discrete Transfer Radiation Model (DTRM) radiation heat transfer model, zoning solution

JiZu Lü; MinLi Bai; XiaoJie Li

2010-01-01

104

Temperature and Composition Measurements in a Research Gas Turbine Combustion Chamber  

Microsoft Academic Search

Profiles of temperature and concentrations of CO, CO2. O2 UHC and NO2 have been measured at various planes within a can-type model gas turbine combustion chamber. The com-bustor is fuelled by high purity gaseous propane and was operated at air inlet temperatures of 313 K. and 523 K and atmospheric pressure simulating high power conditions. The results show that chemical equilibrium conditions

W. P. JONES; H. TORAL

1983-01-01

105

Catalytic relight coating for gas turbine combustion chamber and method of application  

Microsoft Academic Search

A gas turbine combustion chamber is described having a wall with an inner surface exposed to the combustion chamber flame, and a coating of a catalytic material on the surface over a large enough area thereof to cause reignition of the fuel-air mixture after flame-out.

W. C. Pfefferle; M. J. Bak

1986-01-01

106

Research of the influence of combustion chamber structure on performance of dual fuel engine  

Microsoft Academic Search

A research that the influence of combustion chamber's construction parameter on performance of diesel-natural gas dual fuel engine has been done, which is based on a dual fuel engine of diesel-natural gas. The heat release rate of dual fuel engine is calculated and analyzed via the indicated work diagrams of three kinds of different combustion chamber's structural parameter. The research

Du Qian; Ma Fengxian

2011-01-01

107

The Effect of Combustion Chamber Geometry and Injection Timing on Diesel Emission  

Microsoft Academic Search

To improve the soot emissions performance of a common rail diesel engine, two combustion chambers with different diameter-depth ratio were designed under the conditions of the same compression ratio, and using CFD software to simulate the combustion process with different chamber shape and injection timing. The results showed that NOx emissions decreased with the delay of the injection timing, while

Huang Kang; Chang Hanbao; An Shijie; Qin Jianwen

2010-01-01

108

Structure of a main combustion chamber of a diesel engine of a direct injection type  

Microsoft Academic Search

This patent describes a structure of a main combustion chamber of a diesel engine of a direct injection type in which a main combustion chamber having a peripheral wall and a bottom wall is formed by a hollow at a top of a piston, above peripheral wall includes collision walls and guide walls which are disposed alternately to each other

R. Ohashi; H. Inaba

1987-01-01

109

Birdstrike resistant swirler support for combustion chamber dome  

SciTech Connect

An annular combustor is described for a gas turbine engine including a compressor for supplying compressed air to the combustor, comprising: (a) an outer liner; (b) an inner liner spaced radially from the outer liner; (c) a dome structure connecting the outer and inner liners so as to define a combustion chamber the dome structure having a plurality of openings therein; (d) a plurality of fuel cup assemblies mounted to the dome structure so as to align substantially radially to the openings, the fuel cup assemblies being mounted to the dome structure in a mounting plane substantially perpendicular to the openings; (e) a fuel nozzle for delivering fuel to each of the fuel cup assemblies, the fuel to be mixed with the compressed air into a combustible mixture; (f) means for supporting each of the fuel nozzles in the fuel cup assemblies; and (g) means for providing backing support for the fuel nozzle supporting means against rotational movement out of the mounting plane in the event of an impact by a foreign object onto the fuel nozzle supporting means, the backing support means being located downstream of the fuel nozzle supporting means.

Koshoffer, J.M.; Cooper, J.N.; Haas, M.C.; Reinhold, J.N. Jr.

1993-08-31

110

A numerical and experimental study of the squish-jet combustion chamber  

Microsoft Academic Search

The fluid flow characteristics near top dead centre (TDC) were numerically simulated for three different combustion chambers designed to generate squish flow and enhance turbulence generation in spark ignition engines. One of the combustion chambers was a plain bowl-in-piston type while the remaining two were different configurations of the squish-jet chamber, which has a unique geometry for forming jets that

P Lappas; R L Evans

2006-01-01

111

Development of a Rate of Injection Bench and Constant Volume Combustion Chamber for Diesel Spray Diagnostics  

Microsoft Academic Search

To help understand the complex fuel spray combustion phenomena in modern diesel engine using high injection pressure, a fuel injection test bench and a constant volume combustion chamber were developed and demonstrated in this study for diesel spray diagnostics. Both facilities are significant when linking between spray injection and combustion dynamics and engine performance. This link is important to determine

Anthony Phan

2009-01-01

112

Combustion chamber resonances in direct injection automotive diesel engines: A numerical approach  

Microsoft Academic Search

The resonant oscillation of burned gases in the combustion chamber of direct injection (DI) diesel engines appears to be the main excitation source of the engine block during combustion. This has led to the application of different techniques in order to study its generation mechanisms and to determine its relationship with combustion parameters such as bowl geometry, type of injector,

A. J. Torregrosa; A Broatch; X Margot; V Marant; Y Beauge

2004-01-01

113

THERMAL LOADING AND TEMPEARTURE DISTRIBUTION OF A PRE COMBUSTION CHAMBER DIESEL ENGINE RUNNING ON GASOIL \\/ NATURAL GAS  

Microsoft Academic Search

Heat flux and temperature distribution were carried out in the combustion chamber of a pre-combustion chamber diesel engine running on dual fuel of diesel and natural gas. The test rig consists of a pre- combustion chamber single cylinder diesel engine fully equipped for temperature measurements across different points in the cylinder head, cylinder liner and other critical areas of the

Mohamed Y. E. Selim

114

Chamber Clearing First Principles Modeling  

SciTech Connect

LIFE fusion is designed to generate 37.5 MJ of energy per shot, at 13.3 Hz, for a total average fusion power of 500 MW. The energy from each shot is partitioned among neutrons ({approx}78%), x-rays ({approx}12%), and ions ({approx}10%). First wall heating is dominated by x-rays and debris because the neutron mean free path is much longer than the wall thickness. Ion implantation in the first wall also causes damage such as blistering if not prevented. To moderate the peak-pulse heating, the LIFE fusion chamber is filled with a gas (such as xenon) to reduce the peak-pulse heat load. The debris ions and majority of the x-rays stop in the gas, which re-radiates this energy over a longer timescale (allowing time for heat conduction to cool the first wall sufficiently to avoid damage). After a shot, because of the x-ray and ion deposition, the chamber fill gas is hot and turbulent and contains debris ions. The debris needs to be removed. The ions increase the gas density, may cluster or form aerosols, and can interfere with the propagation of the laser beams to the target for the next shot. Moreover, the tritium and high-Z hohlraum debris needs to be recovered for reuse. Additionally, the cryogenic target needs to survive transport through the gas mixture to the chamber center. Hence, it will be necessary to clear the chamber of the hot contaminated gas mixture and refill it with a cool, clean gas between shots. The refilling process may create density gradients that could interfere with beam propagation, so the fluid dynamics must be studied carefully. This paper describes an analytic modeling effort to study the clearing and refilling process for the LIFE fusion chamber. The models used here are derived from first principles and balances of mass and energy, with the intent of providing a first estimate of clearing rates, clearing times, fractional removal of ions, equilibrated chamber temperatures, and equilibrated ion concentrations for the chamber. These can be used to scope the overall problem and provide input to further studies using fluid dynamics and other more sophisticated tools.

Loosmore, G

2009-06-09

115

The effects of inhomogeneity in DME-Air mixture in combustion chamber on homogeneous charge compression ignition combustion  

Microsoft Academic Search

In the HCCI Engine, the inhomogeneity exists in fuel distribution and temperature in the pre-mixture microscopically, and has the possibility of affecting the ignition and combustion process. In this study, the effect of the inhomogeneity in DME\\/n-Butane-Air mixture in the combustion chamber on the HCCl combustion was investigated by chemiluminescence method in order to understand the spatial distribution of the

Ock Taeck Lim; Satoshi KETADANI; Kengo KUMANO; Norimasa IIDA

2007-01-01

116

Experimental study on premix combustion at isosceles triangle type rate of heat release for squish type combustion chamber  

Microsoft Academic Search

This paper presents a theory on premix fuel combustion at near isoceles triangle type rate of heat release, describes the\\u000a measures taken for the combustion system, points out its many theoretical advantages, and that it can solve effectively the\\u000a problems of rough running, fuel consumption and exhaust emission. Two squish lip type combustion chambers are designed to\\u000a match separately with

Yang Zhen-zhong; Li Jing-ding; Hua Xiang-yang

2001-01-01

117

Simulations of shock-induced mixing& combustion of an acetylene cloud in a chamber  

SciTech Connect

In this paper we present numerical simulations of the interaction of a blast wave with an acetylene bubble in a closed chamber. We model the system using the inviscid Euler equations for a mixture of ideal gases. The formulation specifies the thermodynamic behavior of the system using a Chemkin interface and includes the capability to model combustion as the ambient air mixes with the acetylene. The simulations are performed using a three-dimensional adaptive mesh refinement algorithm based on a second-order Godunov integration scheme. Simulations are compared with experimental measurements for the same configuration.

Bell, J B; Day, M S; Beckner, V E; Kuhl, A L; Neuwald, P; Reichenbach, H

2001-02-06

118

Simulation of Turbulent Combustion Using Various Turbulent Combustion Models  

Microsoft Academic Search

The reynolds-averaged navier-stokes (RANS) method nowadays still is the major tool for gas turbine chamber (GTC) designers, but there is not a universal method in RANS GTC spray combustion simulation at present especially for the two- phase turbulent combustion. Usually there are two main steps in two-phase combustion: the liquid fuel evaporation and the gas mixture combustion. Thus, two widely

Fang Wang; Yong Huang; Tian Deng

2009-01-01

119

A thin-film thermocouple for transient heat transfer measurements in ceramic-coated combustion chambers  

Microsoft Academic Search

A chromel-alumel overlapping thin-film thermocouple (TFTC) has been developed for transient heat transfer measurements in ceramic-coated combustion chambers. The TFTC was first evaluated using various metallurgical techniques, and calibrated against a standard thermocouple. Subsequently, the TFTC was tested in a diesel engine combustion chamber operating at 1,900 rpm and full load. A mean temperature of 613 K with a cyclic

D. N. Assanis; F. A. Friedmann

2009-01-01

120

Combustion Chambers for Natural Gas SI Engines Part I: Fluid Flowand Combustion  

Microsoft Academic Search

The most economical way to convert truck and bus DI-diesel engines\\u000d\\u000a\\u0009to natural gas operation is to replace the injector with a spark\\u000d\\u000a\\u0009plug and modify the combustion chamber in the piston crown for spark\\u000d\\u000a\\u0009ignition operation. The modification of the piston crown should give\\u000d\\u000a\\u0009a geometry well suited for spark ignition operation with the original\\u000d\\u000a\\u0009swirling inlet port.\\u000d\\u000a\\u0009\\u000d\\u000a\\u0009\\u000d\\u000a\\u0009Ten

Bengt Johansson; Krister Olsson

1995-01-01

121

The development of a diesel burning combustion chamber with a multiple jet primary zone  

Microsoft Academic Search

A new primary zone for a gas turbine combustor is developed which achieves efficient combustion in fuel lean conditions for minimizing carbon formation. This uses a large number of jets in the head of the chamber to generate independent shear layers in a co-operative array. Good combustion performance, wide fuel\\/air ratio operational range and tolerance to fuel quality have been

R. V. Cottington; J. P. D. Hakluytt; J. R. Tilston

1987-01-01

122

Radiative Heat Transfer in the Combustion Chamber of a Diesel Engine  

Microsoft Academic Search

Radiation is considered to be an important mode of heat transfer in diesel engines. It is mainly caused by a presence of soot particles in combustion gases. Spatial distribution of radiative heat flux on walls of the combustion chamber can be an important factor of thermal load of some parts of the engine. The paper presents a numerical method used

P. Furmanski; J. Banaszek; T. S. Wisniewski

1999-01-01

123

Evaporating spray and flame distributions in the combustion chamber of a direct injection diesel engine  

Microsoft Academic Search

The characteristics of an evaporating diesel spray and the flame distribution in a combustion chamber of a D.I. diesel engine were investigated by using the laser light technique. The technique used was based on the extinctions of two wavelengths of ultraviolet and visible laser light. The transmitted laser light absorbed and scattered by the vapor, drops, soot and combustion products

Takuo Yoshizaki; Osamu Yamamoto; Keiya Nishida; Hiroyuki Hiroyasu; Mamoru Suzuki

1997-01-01

124

Shock-Dispersed-Fuel Charges: Combustion in Chambers and Tunnels  

SciTech Connect

In previous studies we have investigated after-burning effects of a fuel-rich explosive (TNT). In that case the detonation only releases about 30% of the available energy, but generates a hot cloud of fuel that can burn in the ambient air, thus evoking an additional energy release that is distributed in space and time. The current series of small-scale experiments can be looked upon as a natural generalization of this mechanism: a booster charge disperses a (non-explosive) fuel, provides mixing with air and, by means of the hot detonation products, the energy to ignite the fuel. The current version of our miniature Shock-Dispersed-Fuel (SDF) charges consists of a spherical booster charge of 0.5 g PETN, embedded in a paper cylinder of approximately 2.2 cm, which is filled with powdered fuel compositions. The main compositions studied up to now contain aluminum flakes, hydrocarbon powders like polyethylene or hexosen (sucrose) and/or carbon particles. These charges were studied in four different chambers: two cylindrical vessels of 6.6-1 and 40.5-1 volume with a height-to-diameter ratio of approximately 1, a rectangular chamber of 41 (10.5 x 10.5 x 38.6 cm) and a 299.6 cm long tunnel model with a cross section of 8 x 8 cm (volume 19.21) closed at both ends.

Neuwald, P; Reichenbach, H; Kuhl, A L

2003-04-22

125

Application of moire deflectometry in visualizing flow field in a diesel combustion chamber  

NASA Astrophysics Data System (ADS)

In this paper a technique of visualizing flow field in diesel combustion chamber is presented. It consists of laser source, moire deflectometer and high speed camera. Using this setup to visualize the flow field in a single chamber diesel, we gained the series deflectograms of flow field under different conditions and calculate the temperature distribution of its flow field quantitatively.

You, Haihang; Yan, Dapeng; Wang, Zhengdong; He, Anzhi

1997-11-01

126

Application of moire deflectometry in visualizing flow field in a diesel combustion chamber  

Microsoft Academic Search

In this paper a technique of visualizing flow field in diesel combustion chamber is presented. It consists of laser source, moire deflectometer and high speed camera. Using this setup to visualize the flow field in a single chamber diesel, we gained the series deflectograms of flow field under different conditions and calculate the temperature distribution of its flow field quantitatively.

Haihang You; Dapeng Yan; Zhengdong Wang; Anzhi He

1997-01-01

127

Induction system for internal combustion engine having multiple inlet valves per combustion chamber  

SciTech Connect

In an internal combustion engine a combustion chamber is described comprising: first and second inlet valves, the first inlet valve being arranged to open at a first predetermined timing prior the end of the exhaust phase of the engine. The second inlet valve is arranged to open essentially at the end of the exhaust phase; a first conduit leading from a source of air to the first inlet valve; a second induction conduit leading from the source of air to the second inlet valve; an engine throttle valve operatively interposed between the source of air and the first and second induction conduits; a flow control valve disposed in the first induction conduit for cutting off communication between the source of air and the first inlet valve when the engine is operating in a first mode and for permitting the communication when the engine is operating under a second mode; and an air bleed formed only in the first induction conduit at a location downstream of and proximate the flow control valve for permitting a controlled amount of air to enter the first inlet conduit.

Aoyama, S.; Fujii, H.; Kato, M.

1986-12-16

128

A review of internal combustion engine combustion chamber process studies at NASA Lewis Research Center  

NASA Astrophysics Data System (ADS)

The performance of internal combustion stratified-charge engines is highly dependent on the in-cylinder fuel-air mixing processes occurring in these engines. Current research concerning the in-cylinder airflow characteristics of rotary and piston engines is presented. Results showing the output of multidimensional models, laser velocimetry measurements and the application of a holographic optical element are described. Models which simulate the four-stroke cycle and seal dynamics of rotary engines are also discussed.

Schock, H. J.

1984-06-01

129

The Bajulaz Cycle: A two-chamber internal combustion engine with increased thermal efficiency  

SciTech Connect

A new engine cycle, called the Bajulaz cycle, is introduced. The cycle has the unique characteristic that it utilizes two chambers, an air-heating chamber and combustion chamber. By allowing heat transfer from the combustion chamber to the air-heating chamber, the heat of combustion is used more efficiently leading to a higher thermal efficiency. Utilizing an ideal thermodynamic cycle analysis, the thermal efficiency of the Bajulaz cycle is shown to depend only on the compression ratios based on the two chamber volumes and the fractional heat transer between the two chambers. Based on predictions of peak temperature and pressure generated from the ideal cycle analysis, the Bajulaz engine is shown to be thermally more efficient and has lower NO/subX/ emission than the corresponding Otto engine. Combustion is shown to occur over a full 360/sup 0/ of crankshaft rotation in the Bajulaz engine. The Bajulaz engine thus does not have any restrictive requirement on ignition timing (as in an Otto engine) and on the timing and duration of fuel injection (as in a Diesel engine). It can also utilize multiple fuels including those with slow burning rate.

Yuen, W.W.; Andon, J.; Bujulaz, R.

1986-01-01

130

Optical diagnostics and instrumentation for supercritical combustion studies in a LOX\\/H2 rocket engine combustion chamber  

Microsoft Academic Search

Quantitative and qualitative optical diagnostics have been successfully applied within a liquid propellant rocket engine with optical access at representative, supercritical operating conditions. A series of unique optical techniques have been implemented in an attempt to characterise the liquid oxygen (LOX) and hydrogen (H2) spray flames prevalent in today's heavy launch vehicle engines. A windowed, high-pressure combustion chamber has been

D. N. Klimenko; W. Clauss; W. Mayer; M. Oschwald; J. J. Smith

2003-01-01

131

Three-dimension design for combustion chamber system in high speed direct-injection engine using KIVA3V code  

Microsoft Academic Search

To design new combustion chamber system for modern diesel engine three-dimension CFD (computational fluid dynamics) software (KIVA-3V) is used. To improve emission standard original combustion chamber structure (4JB1) is modified and the new one is got. The new combustion chamber structure can fit for modern high-speed CR (common rail) diesel engine and increase compression ratio from 16 to 18.2. Since

Liu Yongfeng; Qiu Tao; Tian Hongsen; Lin Xiuxia

2010-01-01

132

Study on Combustion Chamber Geometry Effects in an HCCI Engine using High-Speed Cycle-Resolved Chemiluminescence Imaging  

Microsoft Academic Search

The aim of this study is to see how geometry generated turbulence affects the Rate of Heat Release (ROHR) in an HCCI engine. HCCI combustion is limited in load due to high peak pressures and too fast combustion. If the speed of combustion can be decreased the load range can be extended. Therefore two different combustion chamber geometries were investigated,

Andreas Vressner; Anders Hultqvist; Bengt Johansson

2007-01-01

133

A review of internal combustion engine combustion chamber process studies at NASA Lewis Research Center  

NASA Astrophysics Data System (ADS)

The performance of internal combustion stratified-charge engines is highly dependent on the in-cylinder fuel-air mixing processes occurring in these engines. Current research concerning the in-cylinder airflow characteristics of rotary and piston engines is presented. Results showing the output of multidimensional models, laser velocimetry measurements and the application of a holographic optical element are described. Models which simulate the four-stroke cycle and seal dynamics of rotary engines are also discussed. Previously announced in STAR as N84-24999

Schock, H. J.

1984-06-01

134

The next step in chemical propulsion: Oxide-iridium/rhenium combustion chambers  

SciTech Connect

Chemical propulsion systems are currently limited by materials issues. Until recently, the state-of-the-art material for liquid propellant combustion chambers was silicide-coated niobium. However, combustion chamber performance demands have exceeded the capabilities of this material system, requiring development of better materials. The iridium/rhenium combustion chamber, comprising a rhenium structural shell with an iridium inner liner for oxidation protection, represents the current state of the art in high-performance, high temperature, long-life propulsion systems using nitrogen tetroxide/monomethyl hydrazine propellant. However, oxygen/hydrogen (O{sub 2}/H{sub 2}) and new 'green' monopropellants under development to replace hydrazine will be significantly more oxidizing at operating temperature. For these more highly aggressive combustion environments, Ultramet has shown that substantial additional life can be obtained by lining the interior of the combustion chamber with a refractory metal oxide, which functions as a thermal and gas diffusion barrier and provides dramatically increased oxidation resistance. Ultramet has fabricated numerous 22-N (5-lb{sub f}) thrust chambers with this oxide-iridium/rhenium architecture that have been hot-fire tested at NASA Lewis Research Center in O{sub 2}/H{sub 2} propellant at mixture ratios of 6 and 16, with steady-state exterior wall temperatures ranging from 2433 to 2899 K, comprising the most severe temperature and oxidizing conditions ever utilized. Of the seven chambers tested to date, three failed due to facility problems, and two never failed. The best-performing chamber was hot-fired for 13,595 seconds (227 minutes; 3.8 hours) and showed no visible signs of degradation. Additional chambers are being fabricated for future testing.

Fortini, Arthur J.; Tuffias, Robert H. [Ultramet, 12173 Montague St., Pacoima, California 91331 (United States)

1999-01-22

135

Formation of detonation in a pulse combustion chamber with a porous obstacle  

NASA Astrophysics Data System (ADS)

A study has been made of the influence of a porous obstacle on deflagration-to-detonation transition in a pulse combustion chamber of small length. Dependences of the detonation-wave velocity on the distance have been obtained for two samples of a porous material (steel spheres and a ceramic porous body). It has been shown that the use of an insert from a porous material leads to a reduction of 40% in the predetonation distance without changing substantially the structure of the pulse combustion chamber.

Alhussan, Kh.; Assad, M. S.; Penyazkov, O. G.; Sevruk, K. L.

2012-09-01

136

An experimental and computational evaluation of two dual-intake-valve combustion chambers  

Microsoft Academic Search

This paper reports on multi-dimensional computations that wle made of spark-ignited premixed-charge combustion in two engines having pent-roof-shaped combustion chambers and two intake valves per cylinder, one with a central spark plug and the other with dual lateral spark plugs. The basic specifications for the two engines were the same except for differences in the number of spark plugs and

P. M. Najt; T. W. Kuo

1990-01-01

137

Three dimensional modelling of combustion in a prechamber diesel engine  

SciTech Connect

Three dimensional modelling appears to be a good way to analyze the influence of the major parameters involved in the diesel combustion process. The computer code KIVA was modified and improved in order to be applicable to very complex combustion chamber shapes. A new mesh generator was used and coupled to KIVA. Modelling the diesel combustion required the implementation of new sub-models in the code. A{kappa}-{epsilon} turbulence model was used. Heat transfer rates to the wall were computed using a model based on a {kappa}-{epsilon} formulation. Combustion was to be controlled by species and heat diffusion only. This assumption allowed the use of the Magnussen Eddy Break Up combustion model. The complete model was applied to the simulation of flow and combustion in a Ricardo COMET prechamber diesel engine. The authors studied the fluid dynamics and the evolution of combustion in both the pre- and main combustion chambers. The influence of the position of the glow plug and of the piston shape were investigated. The studies of the flow show that addition of the glow plug in the prechamber reduces the swirl level to less than half its level without the plug. Comparisons between computational results and experimental flame visualizations performed elsewhere reveal a good qualitative agreement. The computed global heat release rate is found to follow the experimental trends.

Pinchon, P.

1989-01-01

138

Numerical investigation of the flow inside the combustion chamber of a plant oil stove  

NASA Astrophysics Data System (ADS)

Recently a low cost cooking device for developing and emerging countries was developed at KIT in cooperation with the company Bosch und Siemens Hausgeräte GmbH. After constructing an innovative basic design further development was required. Numerical investigations were conducted in order to investigate the flow inside the combustion chamber of the stove under variation of different geometrical parameters. Beyond the performance improvement a further reason of the investigations was to rate the effects of manufacturing tolerance problems. In this paper the numerical investigation of a plant oil stove by means of RANS simulation will be presented. In order to reduce the computational costs different model reduction steps were necessary. The simulation results of the basic configuration compare very well with experimental measurements and problematic behaviors of the actual stove design could be explained by the investigation.

Pritz, B.; Werler, M.; Wirbser, H.; Gabi, M.

2013-10-01

139

A mathematical model of low amplitude pulse combustion systems using a Helmholtz resonator-type approach  

NASA Astrophysics Data System (ADS)

Pulse combustion devices consisting of one or two combustion chamber-pulse tube combinations attached to a exhaust decoupling chamber and a long exhaust pipe were modeled by using Helmholtz resonator concepts. Comparisons of theory with experiment are presented and questions of operational stability are discussed.

Lee, J. H.; Dhar, B.; Soedel, W.

1985-02-01

140

A mathematical model of low amplitude pulse combustion systems using a Helmholtz resonator-type approach  

Microsoft Academic Search

Pulse combustion devices consisting of one or two combustion chamber-pulse tube combinations attached to a exhaust decoupling chamber and a long exhaust pipe were modeled by using Helmholtz resonator concepts. Comparisons of theory with experiment are presented and questions of operational stability are discussed.

J. H. Lee; B. Dhar; W. Soedel

1985-01-01

141

Combustion of Shock-Dispersed Fuels in a Chamber  

SciTech Connect

In previous studies we have investigated after-burning effects of a fuel-rich explosive (TNT). In that case the detonation only releases about 30 % of the available energy, but generates a hot cloud of fuel that can burn in the ambient air, thus evoking an additional energy release that is distributed in space and time. The current series of small-scale experiments can be looked upon as a natural generalization of this mechanism: a booster charge disperses a (non-explosive) fuel, provides mixing with air and - by means of the hot detonation products - energy to ignite the fuel. The current version of our miniature Shock-Dispersed-Fuel (SDF) charges consists of a spherical booster charge of 0.5 g PETN, embedded in a paper cylinder of approximately 2.2 cm3, which is filled with powdered fuel compositions. The main compositions studied up to now contain aluminum powder, hydrocarbon powders like polyethylene or sucrose and/or carbon particles. These charges were studied in three different chambers of 4-1, 6.6-1 and 40.5-1 volume. In general, the booster charge was sufficient to initiate burning of the fuel. This modifies the pressure signatures measured with a number of wall gages and increases the quasi-static overpressure level obtained in the chambers. On the one hand the time-scale and the yield of the pressure rise depend on the fuel and its characteristics. On the other hand they also depend on the flow dynamics in the chamber, which is dominated by shock reverberations, and thus on the chamber geometry and volume. The paper gives a survey of the experimental results and discusses the possible influences of some basic parameters.

Neuwald, P; Reichenbach, H; Kuhl, A L

2003-04-23

142

Modelling coal combustion: the current position  

Microsoft Academic Search

At the present time, computer models for coal combustion are not sufficiently accurate to enable the design of combustion plant or the selection of a coal based on combustion behaviour. Most comprehensive combustion models can predict with reasonable accuracy flow fields and heat transfer, but usually with a much lesser degree of accuracy than the combustion of the coal particles

A. Williams; R. Backreedy; R. Habib; J. M. Jones; M. Pourkashanian

2002-01-01

143

Effect of split injection on fuel distribution in an engine-fed combustion chamber. (Reannouncement with new availability information)  

Microsoft Academic Search

This research focused on the effects of split injection on fuel spray behavior in a diesel environment It was done in a special designed engine-fed combustion chamber (swirl ratio of 5) with full field optical access through a quartz window. The simulated engine combustion chamber used a special backwards spraying injector (1 05`). The electronically controlled injector could control the

G. R. Bower; D. E. Foster

1993-01-01

144

Corrosion prevention in hydrocarbon-fueled booster engine combustion chamber liners  

Microsoft Academic Search

Static and dynamic tests with methane fuels containing trace amounts of sulfur compounds were performed in order to identify and develop procedures to protect against the corrosive interaction process that occurs between the fuel and the copper combustion chamber liner materials in the coolant side of a regeneratively cooled hydrocarbon booster engine. Foils of gold, platinum, zirconium, iridium, niobium, and

S. D. Rosenberg; M. L. Gage

1989-01-01

145

Integrated structural risk-based approach for design and analysis of combustion chamber liners  

Microsoft Academic Search

A structural risk-based approach for design and analysis of combustion chamber liners is presented. The methodology can be used to evaluate a single design or a series of alternate designs. The uncertainty in loads, materials, design variables, fabrication, Nondestructive Evaluation (NDE), testing, and refurbishment of the design are considered. Risk is associated with cost consequences of fabrication failures, proof testing,

J. F. Newell; K. R. Rajagopal

1992-01-01

146

Construction and Calibration of Measuring Probes for the Testing of Combustion Chambers of Jet Engines.  

National Technical Information Service (NTIS)

A description is given of the principles and equipment for temperature and flow measurements in a jet engine combustion chamber. The equipment used consists of a gasdynamic thermometer for the range above 2200C, a double thermocouple for temperatures up t...

B. Niedzialek K. Bednarek

1970-01-01

147

Divided Combustion Chamber Gasoline Engines A Review for Emissions and Efficiency  

Microsoft Academic Search

To facilitate the distinction among different engine types, this paper indicates first a general classification of gasoline engines. This classification contains the group of stratified charge engines, and shows that, within this group, the divided combustion chamber engine type constitutes a major subdivision. Three characteristic designs of this type of engine are described in some detail, and fuel economy and

Jose L. Bascunana

1974-01-01

148

Computerized ultrasonic inspection system for ceramic pre-combustion chambers of automotive diesel engines  

Microsoft Academic Search

A computerized ultrasonic inspection system was developed to inspect small flaws in ceramic pre-combustion chambers of diesel engines for evaluation of their quality. The system comprises a digitalized multi-channel ultrasonic flaw detector, an immersion test scanner, and a multiple transducers and performs the acquisition of inspection data. The scanner is equipped with two sets of scanner arms and a turntable

K. Asai; A. Takeuchi; N. Ueda; J. Kawamoto

1985-01-01

149

Process and device for the introduction of explosive gases into a combustion chamber  

Microsoft Academic Search

When explosive gases are introduced into a combustion chamber care must be taken that no pre-ignition occurs. To this end, the gas is spatially subdivided into discrete volume elements, for example by means of a bundle of tubes having an internal diameter which does not exceed twice the quenching distance of the explosive gases. Such a division ensures that the

K. Bodenbenner; G. Muller; H. Perkow

1981-01-01

150

Impact of Introducing Water into the Combustion Chamber of Diesel Engines on Emissions - an Overview  

Microsoft Academic Search

The method of introducing water with the fuel or directly into the combustion chamber of reciprocating engines has proved to be a powerful and, at the same time, economical tool for reducing oxides of nitrogen (NOx) and particulate matter (PM) in the exhaust gases. Research in this area goes back to the early days of development of aircraft piston engines

X. T. Tran; J. I. Ghojel

151

Study of air swirl and particle movement in diesel combustion chambers  

Microsoft Academic Search

A report is presented on the results of an investigation of the air swirl and the particle movement in the combustion chamber of a D.I. diesel engine. The particle track method is used in the visualization of the flow phenomena. The experimental results show that this method can be satisfactorily used in this field provided that the tracer particles selected

S. X. Shi; S. L. Liu

1981-01-01

152

High-pressure calorimeter chamber tests for liquid oxygen\\/kerosene (LOX\\/RP1) rocket combustion  

Microsoft Academic Search

An experimental program was conducted to investigate the rocket combustion and heat transfer characteristics of liquid oxygen\\/kerosene (LOX\\/RP-1) mixtures at high chamber pressures. Two water-cooled calorimeter chambers of different combustion lengths were tested using 37- and 61-element oxidizer-fuel-oxidizer triplet injectors. The tests were conducted at nominal chamber pressures of 4.1, 8.3, and 13.8 MPa abs (600, 1200, and 2000 psia).

P. A. Masters; E. S. Armstrong; H. G. Price

1988-01-01

153

Premixing gas and air to reduce NO\\/sub x\\/ emissions with existing proven gas turbine combustion chambers  

Microsoft Academic Search

In the case of the burners employed in KWU gas turbine combustion chambers, the entire primary air is supplied through the swirlers associated with the burners. It is thus relatively easy to add natural gas to this air uniformly before it enters the combustion zone. This results in a particularly low NO\\/sub x\\/ combustion process provided that the air to

B. Becker; P. Berenbrink; H. Brandner

1986-01-01

154

Organization of kerosene combustion in a model hypersonic ramjet engine  

Microsoft Academic Search

We present the results of experiments on the organization of kerosene combustion in a two-dimensional model of a hypersonic ramjet engine in conditions of external blow-out by a flow with parameters M8=6, p8*=(53–55)·105 Pa, T8*=1500 K. We studied the operation of some variants of a rectangular combustion chamber with different kerosine injectors and stabilizing elements when hydrogen is used as

V. A. Vinogradov; S. A. Kobyzhskii; M. D. Petrov

1992-01-01

155

Smog chamber study on the evolution of fume from residential coal combustion.  

PubMed

Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking, and emit considerable pollutants to the atmosphere because of no treatment of their exhaust, which can result in deteriorating local air quality. In this study, a dynamic smog chamber was used to investigate the real-time emissions of gaseous and particulate pollutants during the combustion process and a static smog chamber was used to investigate the fume evolution under simulate light irradiation. The real-time emissions revealed that the total hydrocarbon (THC) and CO increased sharply after ignition, and then quickly decreased, indicating volatilization of hydrocarbons with low molecular weight and incomplete combustion at the beginning stage of combustion made great contribution to these pollutants. There was evident shoulder peak around 10 min combustion for both THC and CO, revealing the emissions from vitrinite combustion. Additionally, another broad emission peak of CO after 30 min was also observed, which was ascribed to the incomplete combustion of the inertinite. Compared with THC and CO, there was only one emission peak for NOx, SO2 and particular matters at the beginning stage of combustion. The fume evolution with static chamber simulation indicated that evident consumption of SO2 and NOx as well as new particle formation were observed. The consumption rates for SO2 and NOx were about 3.44% hr(-1) and 3.68% hr(-1), the new particle formation of nuclei particles grew at a rate of 16.03 nm/hr during the first reaction hour, and the increase of the diameter of accumulation mode particles was evident. The addition of isoprene to the diluted mixture of the fume could promote 03 and secondary particle formation. PMID:22783629

Geng, Chunmei; Wang, Kun; Wang, Wei; Chen, Jianhua; Liu, Xiaoyu; Liu, Hongjie

2012-01-01

156

Modeling semi-anechoic electromagnetic measurement chambers  

Microsoft Academic Search

Previous studies developed a model to predict theoretically the low-frequency plane-wave reflection coefficient of an array of pyramid cone absorbers such as those used to line anechoic electromagnetic measurement chambers. The present authors apply this model in a geometrical optics approach to predict the electromagnetic field in a chamber lined with cone absorbers in the frequency range of 30-300 MHz.

Christopher L. Holloway; Edward F. Kuester

1996-01-01

157

Numerical approaches to combustion modeling  

SciTech Connect

This book presents a series of topics ranging from microscopic combustion physics to several aspects of macroscopic reactive-flow modeling. As the reader progresses into the book, the successive chapters generally include a wider range of physical and chemical processes in the mathematical model. Including more processes, however, usually means that they will be represented phenomenologically at a cruder level. In practice the detailed microscopic models and simulations are often used to develop and calibrate the phenomenologies used in the macroscopic models. The book first describes computations of the most microscopic chemical processes, then considers laminar flames and detonation modeling, and ends with computations of complex, multiphase combustion systems.

Oran, E.S.; Boris, J.P. (Naval Research Lab., Washington, DC (United States))

1991-01-01

158

Effect of Triangular Fins on Critical Heat Flux in Ethanol-cooled Combustion Chamber  

NASA Astrophysics Data System (ADS)

A pressure-fed engine with a regeneratively-cooled combustion chamber is studied in JAXA. Operation chamber pressure is approximately 1 MPa. A proposed propellant combination is liquid oxygen and ethanol. However, it is necessary to understand the critical heat flux when ethanol is used as a coolant for regeneratively-cooled combustion chamber because the saturation pressure of it is 6.3 MPa. In general, it is known that the cooling wall with fins improves the cooling performance. In this study, the effect of triangular fins on critical heat flux of ethanol in ethanol-cooled combustion chamber was investigated. As the result, it was found that the critical heat flux of cooling wall with triangular fins was 23 % higher than that of that without fin in the same velocity condition of the coolant. The critical heat flux increases by the triangular fins on the cooling surface due to the effect of the combination cooling with film boiling and nucleate boiling.

Takegoshi, Masao; Suzuki, Ryosuke; Saito, Toshihito; Ono, Fumiei; Hiraiwa, Tetsuo; Tomioka, Sadatake

159

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS  

SciTech Connect

Combustion chamber deposits (CCDs) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components [1]. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recent advances in MS have opened new possibilities for analysis of CCDs. Here we report initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.

Reynolds, J G; Shields, S J; Roos, J W

2001-06-14

160

Hybrid numerical modelling of reverberation chambers  

Microsoft Academic Search

This paper describes recent advancements in hybrid numerical modelling of reverberation chambers (RCs). Motivation of modelling an RC is first described, and challenges in RC modelling are pointed out. Shortcomings and advantages of conventional numerical methods are discussed, and hybrid techniques are introduced to overcome disadvantages of different numerical methods while retaining their respective strengths. Benefits of hybrid methods are

Huapeng Zhao; Zhongxiang Shen; Erping Li

2012-01-01

161

Large Eddy Simulation of the Fuel Injection in Scramjet Combustion Chambers  

NASA Astrophysics Data System (ADS)

Fuel injection in a typical scramjet combustion chamber is a very challenging flow to characterise either in ex- perimental or computational studies. It involves multi- species compressible turbulent features with complex coherent flow structures arising as a result of sonic fuel injection transverse or inclined to the free-stream supersonic flow. In this paper the fuel injection in the HyShot- II combustion chamber is studied using an Implicit LES method employing a modified very high order accurate numerical method. To gain accurate mean inflow boundary conditions, a thermally perfect gas formulation has been employed in preliminary simulations of the inlet ramp and cowl configuration. The results of these simulations are presented and validated against wind tunnel data.

Rana, Z. A.; Thornber, B. J. R.; Drikakis, D.

2011-08-01

162

A study on the unsteady temperature field of combustion chamber wall in a turbocharged gasoline engine  

Microsoft Academic Search

To design and develop a turbocharged engine, it is necessary that a lot of studies should be done to find the chrracteristics\\u000a of engine performance and thermal flow. To accomplish this purpose, turbocharger equipped to a naturally aspirated gasoline\\u000a engine was utilized. A thin-film type temperature probe was made and installed onto the combustion chamber wall to measure\\u000a unsteady temperature.

Sung Bin Han; Nae Hyun Lee; Songyol Lee

1996-01-01

163

Mesh Dependency of Turbulent Reacting Large-Eddy Simulations of a Gas Turbine Combustion Chamber  

Microsoft Academic Search

Convergence of reacting LES predictions for an aeronautical gas turbine combustion chamber is analysed in terms of mesh resolution.\\u000a To do so three fully unstructured meshes containing respectively 1.2, 10.6 and 43.9 million tetrahedra are used to compute\\u000a this fully turbulent reacting flow. Resolution criteria obtained from the mean velocity and reacting fields depict different\\u000a convergence behaviors. Reacting fields and

Guillaume Boudier; Gabriel Staffelbach; Laurent Y. M. Gicquel; Thierry J. Poinsot

164

Burn-out calculations for atomized hydrocarbon fuel in gas turbine combustion chambers  

Microsoft Academic Search

1.A method is proposed for calculating the burn-out of atomized hydrocarbon fuel in gas turbine combustion chambers, in which an evaporation mechanism is realized. (The corresponding value of the Spalding criterion Sl?Lx==f(te\\/tc.t).3.Comparison of the experimental data with the theoretical curve, based on the proposed method of calculation, has shown that the total burn-out times are the same with an accuracy

R. S. Tyul'panov

1966-01-01

165

Aluminum Combustion in Solid Rocket Motor Chamber Environment (Preprint).  

National Technical Information Service (NTIS)

A model for prediction of particle radius and oxide cap size/shape versus time for an aluminum particle tracking a stream-tube through a solid rocket motor port has been developed. Following preliminary calculations leading to a postulated flame structure...

M. K. King

2007-01-01

166

Problems of providing completeness of the methane-containing block-jet combustion in a rocket-ramjet engine's combustion chamber  

NASA Astrophysics Data System (ADS)

Some problems of methane-containing hydrocarbon fuel combustion are discussed. It seems that reduction of methane burnout zone length is one from main problems of designing new type engine. It is very important at the creation of combustion chambers of a rocket-ramjet engine for prospective space shuttle launch vehicles.

Timoshenko, Valeriy I.; Belotserkovets, Igor S.; Gusinin, Vjacheslav P.

2009-11-01

167

Linear and nonlinear acoustics with nonuiform entropy in combustion chambers  

SciTech Connect

A one-dimensional analytical model is presented for calculating the longitudinal acoustic modes of idealized dump-type ramjet engines. A plane flame was studied and incorporated into the combustor model where the flame is allowed to move or oscillate in the combustor. This provides three mechanisms of interaction at the flame sheet: agement to supply the necessary transparency and the ability to transmit data in a lazy fashion. Study of the test-bed system reveals that copy-on-reference address space transmission improves migration effectiveness (performance). Relocations occur up to a thousand times faster, with transfer times independent of process size. Since processes access a small portion of their memory in their lifetimes, the number of bytes transferred between machines drops by up to 96%. Message-handling cost are lowered by up to 94%, and are more evenly distributed across the remote execution. Implementation, instrumentation, and study of the test bed provides more useful information than is possible through a simulation.

Humphrey, J.W.

1987-01-01

168

Combustion instability modeling and analysis  

SciTech Connect

It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO{sub x} emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors. The present study represents a coordinated effort between industry, government and academia to investigate gas turbine combustion dynamics. Specific study areas include development of advanced diagnostics, definition of controlling phenomena, advancement of analytical and numerical modeling capabilities, and assessment of the current status of our ability to apply these tools to practical gas turbine combustors. The present work involves four tasks which address, respectively, (1) the development of a fiber-optic probe for fuel-air ratio measurements, (2) the study of combustion instability using laser-based diagnostics in a high pressure, high temperature flow reactor, (3) the development of analytical and numerical modeling capabilities for describing combustion instability which will be validated against experimental data, and (4) the preparation of a literature survey and establishment of a data base on practical experience with combustion instability.

Santoro, R.J.; Yang, V.; Santavicca, D.A. [Pennsylvania State Univ., University Park, PA (United States); Sheppard, E.J. [Tuskeggee Univ., Tuskegee, AL (United States). Dept. of Aerospace Engineering

1995-12-31

169

Toward the Impact of Fuel Evaporation-Combustion Interaction on Spray Combustion in Gas Turbine Combustion Chambers. Part II: Influence of High Combustion Temperature on Spray Droplet Evaporation  

Microsoft Academic Search

\\u000a While the first part of this work dealt with the question related to the impact of partial vaporization on spray flame properties,\\u000a the second part attempts to answer the question how the evaporation process behaves under turbulent premixed combustion conditions.\\u000a According to the Eulerian-Lagrangian RANS-based spray module designed in Part I the non-equilibrium evaporation model, that\\u000a was proven to capture accurately

Amsini Sadiki; W. Ahmadi; Mouldi Chrigui

170

Computational study of the sensitivity to ignition characteristics of the resonance in DI diesel engine combustion chambers  

Microsoft Academic Search

Purpose – The purpose of this computational fluid dynamics (CFD) study is to give insight about the influence of the piston bowl geometry and the fuel ignition features on the resonance of direct injection diesel engines combustion chambers in order to provide support to the experimental findings on combustion noise. Design\\/methodology\\/approach – The resonance due to the burned gases oscillations

Alberto Broatch; Xandra Margot; Antonio Gil

2007-01-01

171

Modeling the internal combustion engine  

SciTech Connect

A flexible and computationally economical model of the internal combustion engine was developed for use on large digital computer systems. It is based on a system of ordinary differential equations for cylinder-averaged properties. The computer program is capable of multicycle calculations, with some parameters varying from cycle to cycle, and has restart capabilities. It can accommodate a broad spectrum of reactants, permits changes in physical properties, and offers a wide selection of alternative modeling functions without any reprogramming. It readily adapts to the amount of information available in a particular case because the model is in fact a hierarchy of five models. The models range from a simple model requiring only thermodynamic properties to a complex model demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. Among its many features the model includes heat transfer, valve timing, supercharging, motoring, finite burning rates, cycle-to-cycle variations in air-fuel ratio, humid air, residual and recirculated exhaust gas, and full combustion kinetics.

Zeleznik, F.J.; Mcbride, B.J.

1985-03-01

172

Vibration prediction in combustion chambers by coupling finite elements and large eddy simulations  

NASA Astrophysics Data System (ADS)

To decrease NO emissions from combustion systems, lean premixed combustion is used. A disadvantage is the higher sensitivity to combustion instabilities, leading to increased sound pressure levels in the combustor and resulting in an increased excitation of the surrounding structure: the liner. This causes fatigue, which limits the life time of the combustor. This paper presents a method to calculate these liner vibrations. The time-dependent pressures on the liner are calculated using large eddy simulation (LES) for both steady combustion and combustion with a pulsated fuel flow. These pressures are interpolated on a finite element grid and used in a transient analysis with a finite element model of the liner structure. The calculated vibrations agree well with experiments made on a 500 kW test rig.

Huls, R. A.; Sengissen, A. X.; van der Hoogt, P. J. M.; Kok, J. B. W.; Poinsot, T.; de Boer, A.

2007-07-01

173

Heat loss to the combustion chamber wall with deposit in D.I. diesel engine: variation of instantaneous heat flux on piston surface with deposit  

Microsoft Academic Search

Adhesion of deposit on the combustion chamber walls affects the state of the heat loss into combustion chamber wall surfaces in the internal combustion engine. In this study, as the first step, the instantaneous surface temperature and the instantaneous heat flux were measured by thin film thermocouples on piston surfaces in the D.I. diesel engine with the adhesion of deposit

Yuichi Yamada; Masahiko Emi; Hiroyuki Ishii; Yasuko Suzuki; Shuji Kimura; Yoshiteru Enomoto

2002-01-01

174

Steady state HNG combustion modeling  

SciTech Connect

Two simplified modeling approaches are used to model the combustion of Hydrazinium Nitroformate (HNF, N{sub 2}H{sub 5}-C(NO{sub 2}){sub 3}). The condensed phase is treated by high activation energy asymptotics. The gas phase is treated by two limit cases: the classical high activation energy, and the recently introduced low activation energy approach. This results in simplification of the gas phase energy equation, making an (approximate) analytical solution possible. The results of both models are compared with experimental results of HNF combustion. It is shown that the low activation energy approach yields better agreement with experimental observations (e.g. regression rate and temperature sensitivity), than the high activation energy approach.

Louwers, J.; Gadiot, G.M.H.J.L. [TNO Prins Maurits Lab., Rijswijk (Netherlands); Brewster, M.Q. [Univ. of Illinois, Urbana, IL (United States); Son, S.F. [Los Alamos National Lab., NM (United States); Parr, T.; Hanson-Parr, D. [Naval Air Warfare Center, China Lake, CA (United States)

1998-04-01

175

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS  

SciTech Connect

Combustion chamber deposits (CCD) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recently, we have reported on the metal structure by XPS and XAS of several deposits from a GM 3800 engine generated using a standard fuel and one that contains low levels of the gasoline anti-knock additive, MMT. Here we report the initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.

Reynolds, J G; Shields, S J; Roos, J W

2001-06-14

176

Modeling of Laser-Induced Metal Combustion  

SciTech Connect

Experiments involving the interaction of a high-power laser beam with metal targets demonstrate that combustion plays an important role. This process depends on reactions within an oxide layer, together with oxygenation and removal of this layer by the wind. We present an analytical model of laser-induced combustion. The model predicts the threshold for initiation of combustion, the growth of the combustion layer with time, and the threshold for self-supported combustion. Solutions are compared with detailed numerical modeling as benchmarked by laboratory experiments.

Boley, C D; Rubenchik, A M

2008-02-20

177

Measurement of the flow field in a diesel engine combustion chamber after combustion by cross-correlation of high-speed photographs  

NASA Astrophysics Data System (ADS)

A cellular cross-correlation technique is applied to high-speed photographs of the luminous phase of combustion in a high-speed direct-injection diesel engine. The method enables the velocity and vorticity distributions in the combustion chamber to be evaluated. The results obtained from the basic technique are refined to remove spurious results and to complete the definition of the flow field by applying data validation, interpolation, and smoothing. The velocity and vorticity fields evaluated at two swirl ratios show the way in which the basically solid body swirl motion interacts with the fuel jets in the combustion chamber. A better understanding of the post-combustion fluid motion is obtained, and this should be of help in validating CFD codes and also the design of engines.

Sun, J. H.; Yates, D. A.; Winterbone, D. E.

1996-03-01

178

Influence of combustion conditions on the PCDD\\/F-, PCB, PCBz- and PAH-concentrations in the post-combustion chamber of a waste incineration pilot plant  

Microsoft Academic Search

Experiments at a pilot scale waste incinerator (0.5 MW thermal power) showed that the conditions in the post-combustion chamber (650–900°C) are strongly influencing the formation of chlorinated and non-chlorinated aromatics. Non-optimal combustion conditions resulted in increased concentrations of mono- to trichlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and polycyclic aromatic hydrocarbons (PAH), while chlorinated benzenes (PCBz), polychlorinated biphenyls (PCB) and the higher

M Blumenstock; R Zimmermann; K.-W Schramm; A Kettrup

2000-01-01

179

Measurement of the flow field in a diesel engine combustion chamber after combustion by cross-correlation of high-speed photographs  

Microsoft Academic Search

A cellular cross-correlation technique is applied to high-speed photographs of the luminous phase of combustion in a high-speed direct-injection diesel engine. The method enables the velocity and vorticity distributions in the combustion chamber to be evaluated. The results obtained from the basic technique are refined to remove spurious results and to complete the definition of the flow field by applying

J. H. Sun; D. A. Yates; D. E. Winterbone

1996-01-01

180

Formation, ignition, and combustion of a stratified-charge fuel-air mixture in an open-chamber combustion bomb. [Thesis  

Microsoft Academic Search

The interrelated processes of mixture formation, ignition, and the early stages of combustion that occur in one type of open-chamber, stratified-charge engines were studied experimentally by simulating engine conditions in a constant-volume combustion bomb. The apparatus designed and developed for this research permits a well-controlled single injection of liquid fuel into a steady-state environment of hot, high-pressure, fan-driven swirling air

1975-01-01

181

Combustion modelling of diesel fuel, seed oils and methyl ester of seed oils  

SciTech Connect

A phenomenological model having modular formulation is presented for combustion in the open chamber diesel engine. The modules for fuel injection, jet penetration and droplet formation have been calibrated outside the engine in a high pressure, fixed volume chamber by high speed photographic and laser analysis of single spray 'shots'. In the diagnostic mode of operation, the chemical components of the combustion reaction are estimated. In the predictive mode of operation the model is used to estimate engines' pressure diagrams and various other combustion characteristics of the fuels over a wide range of speed and load conditions.

Kumar, S.; Watson, H.; Milkins, E.; Edsell, J.

1986-01-01

182

Combustion behaviors and flame structure of methane/coal dust hybrid in a vertical rectangle chamber  

SciTech Connect

Methane/coal dust hybrid flame propagating in a vertical rectangle chamber was examined experimentally. In these experiments, the coal dusts were dispersed into the chamber by premixed methane/air mixture flow to form a methane/coal dust/air hybrid and the hybrid was ignited by an electrode spark. A high-speed video camera was used to record the images of the propagating flame, and a photodiode was used to study the emitting light characteristics of the flame. Micro-thermocouples and ion current probes were used to obtain temperature profiles and reaction behaviors of the combustion zone, respectively. Based on experimental results, combustion behaviors and flame structure of methane/coal dust hybrid propagating flame were analyzed. After the methane/coal dust hybrid is ignited by the electrode spark, the flame begins to propagate in the chamber. The flame front propagates downwards in the initial 20ms, and then propagates upwards. The flame emits strong yellow light and the luminous zone length increases during propagation. The measured temperature starts to increase at a position about 2.15cm ahead of the reaction zone, then to a maximum value near the end of the reaction zone and then subsequently decreases. The chemical reaction begins while the temperature is about 200{sup o}C, and the reaction intensity increases quickly with the temperature increasing. The reaction intensity increases to the maximum value while the temperature is about 500 {sup o}C and then decreases gradually. According to the measured temperature and ion current curves, the preheated zone of the methane/coal dust hybrid is about 2.15cm in width.

Chen, D.L.; Sun, J.H.; Wang, Q.S.; Liu, Y. [University of Science & Technology China, Hefei (China)

2008-07-01

183

Turbulent combustion modelling in a side dump ramjet combustor  

SciTech Connect

Experimental and theoretical studies are reported on the turbulent flow in a side dump rectangular combustor. Hot wire velocimetry was used to measure the axial and transverse mean velocity and turbulence intensity components in the nonreacting case. Flow oscillations in nonreacting case are determined from spectral analysis of the signal. In the presence of combustion, gas analysis (CO, CO2) was carried out in the chamber to obtain the temperature field. Light emission from CH radicals provides additional information which is interpreted as mean rate of heat release per unit volume. Regions where combustion takes place are identified. Measurements are compared with calculations performed with a combustion model relying on the flamelet concept and using a transport equation for the surface density. Good agreement is achieved between the model predictions and experimental results. 26 refs.

Montazel, X.; Samaniego, J.M.; Lacas, F.; Poinsot, T.; Candel, S. (Aerospatiale, Centre des Gatines, Verrieres-le-Buisson (France) Laboratoire d'Energetique Moleculaire et Macroscopique-Combustion, Chatenay-Malabry (France))

1992-07-01

184

Experiments and Simulations of n Heptane Spray Auto-Ignition in a Closed Combustion Chamber at Diesel Engine Conditions  

Microsoft Academic Search

Auto-igniting n-heptane sprays have been studied experimentally in a high pressure, high temperature constant volume combustion chamber with\\u000a optical access. Ignition delay and the total pressure increase due to combustion are highly repeatable whereas the ignition\\u000a location shows substantial fluctuations. Simulations have subsequently been performed by means of a first-order fully elliptic\\u000a Conditional Moment Closure (CMC) code. Overall, the simulations

Yuri M. Wright; Ourania-Nektaria Margari; Konstantinos Boulouchos; Giorgio De Paola; Epaminondas Mastorakos

2010-01-01

185

Flow visualization using the laser light sheet method in vehicle aerodynamics and combustion chamber engineering  

NASA Astrophysics Data System (ADS)

Laser light sheet flow visualization is applied in the automobile industry with a view to the reduction of air resistance. Using high power lasers a plane is cut out of the 3-D flow field and the course of flow in the plane is analyzed. In vehicle aerodynamics the flow phenomena are mainly visualized with smoke in the tail region of automobiles and in the wake, in planes parallel as well as perpendicular to the flow direction. For the investigation of flow phenomena in the combustion chamber of Otto and Diesel engines, the laser light sheet method is used on a series motor with optical access, the so-called flow motor. Typical results and requirements for future automated evaluation methods are discussed.

Hentschel, Werner

186

ANALYSIS OF THE TURBULENT, NON-PREMIXED COMBUSTION OF NATURAL GAS IN A CYLINDRICAL CHAMBER WITH AND WITHOUT THERMAL RADIATION  

Microsoft Academic Search

This work presents a numerical simulation of the non-premixed combustion of natural gas in atmospheric air in an axis-symmetric cylindrical chamber, focusing on the effect of thermal radiation on the temperature and chemical species concentration fields and the heat transfer. The simulation is based on the solution of the mass, energy, momentum and the chemical species conservation equations. Thermal radiation

C. V. SILVA; F. H. R. FRANÇA; H. A. VIELMO

2007-01-01

187

Ignition in conditions where a jet of fuel-air mixture interacts with the wall of a diesel combustion chamber  

Microsoft Academic Search

The dependence of the ignition delay and the limitting detonation temperature of fuel-air mixture on the geometric characteristics of the wall of a diesel combustion chamber at which a high-speed jet is incident is investigated experimentally on a motorless setup. It is shown that, to facilitate ignition in the characteristic conditions of diesel startup, glancing initial incidence of the jet

V. K. Baev; A. A. Buzukov; B. P. Timoshenko

1995-01-01

188

Principle of soft x-ray Moire deflectometry for flow-field visualization in a diesel combustion chamber  

Microsoft Academic Search

The technique based on Moire deflectometry with soft x-ray laser beam has been demonstrated by the research group of D. Ress in the research of plasma produced by laser. We apply this method to visualize the flow field in diesel combustion chamber, and it is also a new application in the world. When a beam of collimated light passes through

Haihang You; Dapeng Yan; Zhengdong Wang; Anzhi He

1997-01-01

189

Numerical analysis of aerodynamics and hydraulic loss in the GTÉ-150 combustion chamber of gas-turbine power plant with the use of the fluent suite  

Microsoft Academic Search

The aerodynamic structure of the flow in the combustion chamber of the GTÉ-150 gas-turbine power plant has been simulated\\u000a numerically by means of the FLUENT suite CFD. The influence of the processes of turbulent heat and mass transfer (and combustion)\\u000a on the hydraulic loss in the combustion chamber has been investigated. Detailed comparison of the calculated and experimental\\u000a data on

D. A. Lysenko; A. A. Solomatnikov

2006-01-01

190

Stratified combustion type engine  

Microsoft Academic Search

The present invention relates to a stratified combustion type engine comprising an engine cylinder, a main combustion chamber located above the cylinder, an injection nozzle for injecting auxiliary fuel towards the combustion chamber, and an open pre-combustion chamber provided within the combustion chamber for locally holding and vaporizing the flow of auxiliary fuel from the injection nozzle. The pre-combustion chamber

Kamiya

1977-01-01

191

Stratified combustion type engine  

Microsoft Academic Search

A stratified combustion type engine is described that is comprised of an engine cylinder, a main combustion chamber located above the cylinder, an injection nozzle for injecting auxiliary fuel towards the combustion chamber, and an open pre-combustion chamber provided within the combustion chamber for locally holding and vaporizing the flow of auxiliary fuel from the injection nozzle. The pre-combustion chamber

Kamiya

1978-01-01

192

Combustion Response Modeling for Composite Solid Propellants.  

National Technical Information Service (NTIS)

A computerized mathematical model of the combustion response function of composite solid propellants was developed with particular attention to the contributions of the solid phase heterogeneity. The one-dimensional model treats the solid phase as alterna...

1977-01-01

193

Integrated Approach to Spray Combustion Model Development.  

National Technical Information Service (NTIS)

The major elements of an approach to the development of a more powerful spray combustion model is discussed. A model is sought that treats, in a numerically-efficient manner, unsteady, multidimensional, turbulent reacting flows with polydisperse, multicom...

W. A. Sirignano

1986-01-01

194

Laminar flamelet modelling of turbulent combustion  

Microsoft Academic Search

The incorporation of a laminar flamelet description into the presumed pdf approach to turbulent combustion modelling is reviewed. A significant advantage of this approach is that it permits the calculation of a library of strained laminar flame solutions, with realistic chemical kinetics included, separately from subsequent turbulent flow-field predictions. A unity of approach is identified between premixed and nonpremixed combustion

K. N. C. Bray

195

Modelling new particle formation from Jülich plant atmosphere chamber and CERN CLOUD chamber measurements  

NASA Astrophysics Data System (ADS)

An MALTE-BOX model is used to study the effects of oxidation of SO2 and BVOCs to new particle formation from Jülich Plant Atmosphere Chamber and CERN CLOUD chamber measurements. Several days of continuously measurements were chosen for the simulation. Our preliminary results show that H2SO4 is one of the critical compounds in nucleation process. Nucleation involving the oxidation of BVOCs shows better agreements with measurements.

Liao, Li; Boy, Michael; Mogensen, Ditte; Schobesberger, Siegfried; Franchin, Alessandro; Mentel, Thomas F.; Kleist, Einhard; Kiendler-Scharr, Astrid; Kulmala, Markku; dal Maso, Miikka

2013-05-01

196

Effect of the PLAZMAZER plasma ignition system on the fuel combustion regimes in combustion chambers of engines  

Microsoft Academic Search

An economically efficient method of combatting toxic products of incomplete fuel combustion in engines and other movable and\\u000a stationary power installations by means of pulsed automatic control of the ignition and combustion processes carried out by\\u000a the PLAZMAZER system is proposed. A new concept of the occurrence of motor knock in internal combustion engines with external\\u000a carburetion, the stiff operating

V. P. Vovk; A. A. Egorov; V. N. Shkatulo

1999-01-01

197

Gasdynamic Model of Turbulent Combustion in TNT Explosions  

SciTech Connect

A model is proposed to simulate turbulent combustion in confined TNT explosions. It is based on: (i) the multi-component gasdynamic conservation laws, (ii) a fast-chemistry model for TNT-air combustion, (iii) a thermodynamic model for frozen reactants and equilibrium products, (iv) a high-order Godunov scheme providing a non-diffusive solution of the governing equations, and (v) an ILES approach whereby adaptive mesh refinement is used to capture the energy bearing scales of the turbulence on the grid. Three-dimensional numerical simulations of explosion fields from 1.5-g PETN/TNT charges were performed. Explosions in six different chambers were studied: three calorimeters (volumes of 6.6-l, 21.2-l and 40.5-l with L/D = 1), and three tunnels (L/D = 3.8, 4.65 and 12.5 with volumes of 6.3-l) - to investigate the influence of chamber volume and geometry on the combustion process. Predicted pressures histories were quite similar to measured pressure histories for all cases studied. Experimentally, mass fraction of products, Y{sub p}{sup exp}, reached a peak value of 88% at an excess air ratio of twice stoichiometric, and then decayed with increasing air dilution; mass fractions Y{sub p}{sup calc} computed from the numerical simulations followed similar trends. Based on this agreement, we conclude that the dominant effect that controls the rate of TNT combustion with air is the turbulent mixing rate; the ILES approach along with the fast-chemistry model used here adequately captures this effect.

Kuhl, A L; Bell, J B; Beckner, V E

2010-01-08

198

Tissue chamber model of acute inflammation in farm animal species  

Microsoft Academic Search

A tissue chamber model of acute inflammation for use in comparative studies in calves, sheep, goats and pigs has been established and validated. Tissue chambers were prepared from silicon rubber tubing, of inner diameter 12.7mm, length 115mm and volume 15ml, with 10 holes, each of 6mm diameter, at each end. In each animal two or four chambers were inserted at

P Sidhu; F Shojaee Aliabadi; M Andrews; P Lees

2003-01-01

199

Hydrocarbon-fuel\\/combustion-chamber-liner materials compatibility. Interim final report, 7 November 1986-31 October 1989  

Microsoft Academic Search

Results of material compatibility experiments using hydrocarbon fuels in contact with copper-based combustion chamber liner materials are presented. Mil-Spec RP-1, n- dodecane, propane, and methane fuels were tested in contact with OFHC, NASA-Z, and ZrCu coppers. Two distinct test methods were employed. Static tests, in which copper coupons were exposed to fuel for long durations at constant temperature and pressure,

Gage

1990-01-01

200

Numerical analysis of thermal turbulent flow in the bowl-in-piston combustion chamber of a motored engine  

Microsoft Academic Search

A numerical analysis of transient turbulent thermal flow has been presented for the bowl-in-piston combustion chamber in a motored engine employing the Large Eddy Simulation which was implemented into the SIMPLE-C algorithm coupled with pre-conditioned conjugate gradient methods. The operating conditions for an engine are changed by various compression ratios (taken as 6.8, 8.7, and 10.6) and initial swirl ratios

Horng-Wen Wu; Shiang-Wuu Perng

2004-01-01

201

The influence of some synfuels on the performance and thermal loading of a pre-combustion chamber diesel engine  

Microsoft Academic Search

Blends of different proportions of straight run naphtha\\/gas oil and BTX\\/Gas oil were used in a four-stroke pre-combustion chamber diesel engine in order to illustrate the aspects of performance and thermal loading likely to arise when using syncrudes, multifuel or coal derived fuel. The engine was instrumented for performance monitoring as well as for heat flux and metal temperature measurement

Radwan

1985-01-01

202

Influence of the kind of fuel oil on the deposit composition in the diesel engine combustion chamber  

Microsoft Academic Search

The authors studied deposits from combustion chambers of high-pressure engines supplied with standard fuel (SO) and ecological fuel of City-Diesel type. Chemical analysis, X-ray diffractograms, Mössbauer absorption and additionally Raman wavenumber measurements were made. The wearing of some engine elements was examined by the profilometric method. By using ecological fuel, the deposits were shown to contain four to five times

P. Tarkowski; J. Sarzy?ski; P. Budzy?ski; R. Paluch; M. Wiertel

2001-01-01

203

Linking a one-dimensional reverberation chamber model with real Reverberation Chambers  

Microsoft Academic Search

Our work focuses on the study of a simple yet complete one-dimensional reverberation chamber model presented previously. The statistical properties of the fields are introduced either by varying the width or the relative dielectric constant of a perturbing lossless layer. Our aim is to show the excellent agreement between this simple model and real RCs. The field statistics in undermoded

Ramiro Serra; Flavio Canavero

2008-01-01

204

Combustion Modelling in Automotive Engines  

Microsoft Academic Search

Before the emissions and energy crises were upon us, it was enough that automotive engines worked. We could develop in a leisurely way our basic understanding of engine combustion problems. It is now obvious that the current automobile engine's problems of high emissions and deteriorating fuel economy must be rapidly solved. It is likely that new engine concepts must be

John B. Heywood

1974-01-01

205

Flow, spray and combustion analysis by laser techniques in the combustion chamber of a direct-injection diesel engine  

Microsoft Academic Search

The purpose of this paper is to show how the analysis of in -cylinder flow, fuel injection, and combustion by means of state-of-the-art optical techniques, as laser light-sheet, laser doppler anemometry and laser shadowgraphy, can help to support the understanding of the interaction of swirl flow development, spray formation, auto-ignition and combustion in near production-line direct-injection diesel engines and thus

W. Hentschel; K.-P. Schindler

1996-01-01

206

Modeling the unsteady combustion of solid propellants with detailed chemistry  

NASA Astrophysics Data System (ADS)

Unsteady combustion phenomena are of great interest to the solid propellant community and have been studied for many years. One area of particular interest is the relation between fluctuating pressure and propellant combustion. Pressure fluctuations, such as acoustics, naturally occur inside solid rocket combustion chambers during motor firing. Coupling between these pressure waves and the burning propellant can lead to changes in burning characteristics, a loss of performance, or even motor failure. During the past several years, various researchers have employed detailed chemical reaction mechanisms for modeling steady-state propellant combustion. The current work extends steady-state modeling into the unsteady domain and is particularly focused on the pressure-coupled phenomena. A numerical model was developed to calculate homogeneous propellant combustion under steady or unsteady conditions. The model was separated into two regions: the condensed and gas phases. Variable properties, distributed decomposition and evaporation were included in the condensed phase. The gas phase included detailed chemistry and the solution of the continuity, species, momentum and energy equations. Application was made to the cyclic nitramines, RDX and HMX. Modeling results were obtained for a wide variety of conditions including (1) steady-state; (2) quasi-steady gas phase, unsteady condensed phase; and (3) fully unsteady gas phase, unsteady condensed phase. The effects of pressure and radiant heat flux oscillations were examined through model simulations. It is believed that this work represents the first successful effort to implement both detailed kinetics and a fully unsteady gas phase for oscillatory propellant combustion. Reasonable agreement with steady-state experimental data was achieved for many combustion parameters including burning rate, surface temperature, melt layer thickness, and species concentration profiles. Pressure and heat flux responses (Rp and Rq) were obtained through numerical simulations. Reasonable agreement with experimental data was attained for many cases. In cases where the model failed to predict experimental results, explanations are given. The quasi-steady gas phase assumption was evaluated by comparing quasi-steady simulations with fully unsteady simulations at the same conditions. At low frequencies, the results coincide, but deviations begin to occur above about 100 Hz at atmospheric pressure and above about 1000 Hz for 1000 psi.

Erikson, William W.

207

Low-emission combustion of a pre-chamber-type compression ignition natural gas engine  

Microsoft Academic Search

A pre-chamber-type compression ignition natural gas engine was constructed and its performance and NO emissions were investigated. The pre- and main chambers made of ceramics were connected by a throat valve that opened during the compression stroke. An homogenous fuel air charge mixed with exhaust gas recirculation (EGR) gases was introduced into the main chamber, while a smaller amount of

H Sasaki; S Sekiyama; M Hashimoto; K Nakashima

2007-01-01

208

Stove with multiple chambers  

Microsoft Academic Search

A stove is described for burning a solid fuel such as wood. The wall means defines a main air inlet, a combustion gas outlet, and four chambers through which gas passes sequentially from the main air inlet to the combustion gas outlet. The chambers comprises a pre-heat plenum chamber into which the main air inlet opens. A main combustion chamber

1987-01-01

209

Spray combustion modeling. Final report  

SciTech Connect

Concern over the future availability of high quality liquid fuels or use in furnaces and boilers prompted the U. S. Department of Energy (DOE) to consider alternate fuels as replacements for the high grade liquid fuels used in the 1970`s and 1980`s. Alternate fuels were defined to be combinations of a large percentage of viscous, low volatility fuels resulting from the low end of distillation mixed with a small percentage of relatively low viscosity, high volatility fuels yielded by the high end of distillation. The addition of high volatility fuels was meant to promote desirable characteristics to a fuel that would otherwise be difficult to atomize and burn and whose combustion would yield a high amount of pollutants. Several questions thus needed to be answered before alternate fuels became commercially viable. These questions were related to fuel atomization, evaporation, ignition, combustion and pollutant formation. This final report describes the results of the most significant studies on ignition and combustion of alternative fuels.

Bellan, J. [Jet Propulsion Lab., Pasadena, CA (United States)

1997-03-01

210

Thermal load in D.I. diesel engine under EGR operation— measurements of steady state temperature of combustion chamber wall surface and intake gas temperature  

Microsoft Academic Search

The combustion temperature drops with exhaust gas recirculation (EGR), but the mean gas temperature in the combustion chamber may rise due to the rise of intake gas temperature and the drop of excess air ratio. For the verification of these effects, narrow J-type thermocouples were embedded in the piston and cylinder liner of an automobile D.I. diesel engine, and accurate

Yoshiteru Enomoto; Hiroshi Nagano; Yuji Hagihara; Takeshi Koyama

1997-01-01

211

Challenges of oxyfuel combustion modeling for carbon capture  

NASA Astrophysics Data System (ADS)

From the policies scenario from Internal Energy Agency (IEA) in 2010, global energy demand for coal climbs from 26% in 2006 to 29% in 2030 and most of demands for coal comes from the power-generation sector [1]. According to the new Copenhagen protocol [3], Global CO2 emission is rising from power generation due to an increasing world demand of electricity. For Energy-related CO2 emission in 2009, 43% of CO2 emissions from fuel combustion were produced from coal, 37% from oil and 20% from gas [4]. Therefore, CO2 capture from coal is the key factor to reduce greenhouse gas emission. Oxyfuel combustion is one of the promising technologies for capturing CO2 from power plants and subsequent CO2 transportation and storage in a depleted oil or gas field or saline-aquifer. The concept of Oxyfuel combustion is to remove N2 from the combustion process and burn the fuel with a mixture composed of O2 and CO2 together with recycled flue gas back into combustion chamber in order to produce a flue gas consisting mainly of CO2. This flue gas can be easily purified, compressed and transported to storage sites. However, Oxyfuel plants are still in the phase of pilot-scaled projects [5] and combustion in Oxyfuel conditions must be further investigated for a scale-up plant. Computational fluid dynamics (CFD) serves as an efficient tool for many years in Oxyfuel combustion researches [6-12] to provide predictions of temperature, heat transfer, and product species from combustion process inside furnace. However, an insight into mathematical models for Oxyfuel combustion is still restricted due to many unknown parameters such as devolatilization rate, reaction mechanisms of volatile reactions, turbulent gaseous combustion of volatile products, char heterogeneous reactions, radiation properties of gaseous mixtures and heat transfer inside and through furnace's wall. Heat transfer drastically changes due to an increasing proportion of H2O and CO2 in these Oxyfuel conditions and the degree of changes depends on the amount of both mentioned gases because both gases have higher thermal heat capacity than N2 in air-fired combustion processes and also are a good emitter and absorber of radiation [13-14]. The mentioned mathematical models are investigated using numerical CFD software (ANSYS FLUENT 12.0) [15] to provide predictions of aerodynamics, thermo-chemical and heat transfer quantities. The numerical models of lignite combustion under oxy-fuel conditions are first investigated in laboratory scaled furnace applying correlations for weighted sum of gray gases (WSGG) model for the predictions of radiation properties of oxy-fuel gas mixture [16]. The developed numerical models are further used for the predictions of temperature, hemi-spherical incident intensity and species concentrations (O2, CO2, H2O) for a 0.4 MWth oxy-fuel furnace at BTU Cottbus.

Kangwanpongpan, T.; Klatt, M.; Krautz, H. J.

2012-04-01

212

Modelling ionization chamber response to nonstandard beam configurations  

NASA Astrophysics Data System (ADS)

Novel technologies aiming at improving target dose coverage while minimising dose to organs at risk use delivery of radiation fields that significantly deviate from reference conditions defined in protocols such as TG-51 and TRS-398. The use of ionization chambers for patient-specific quality assurance of these new delivery procedures calibrated in reference conditions increases the uncertainties on dose delivery. The conversion of the dose to the chamber cavity to the dose to water becomes uncertain; and the geometrical details of the chamber, as well as the details of the delivery, are expected to be significant. In this study, a realistic model of the Exradin® A12 Farmer chamber is simulated. A framework is applied for the calculation of ionization chamber response to arbitrarily modulated fields as a summation of responses to pencil beams. This approach is used with the chamber model and tested against measurements in static open fields and dynamic MLC IMRT fields. As a benchmark test of the model, quality conversion factors values calculated by Monte-Carlo simulation with the chamber model are in agreement within 0.1 % and 0.4 % with those in the AAPM TG-51, for 6 MV and 18 MV photon beams, respectively. Pencil-beam kernels show a strong dependence on the geometrical details of the chamber. Kernel summations with open fields show a relative agreement within 4.0 % with experimental data; the agreement is within 2.0 % for dynamic MLC IMRT beams. Simulations show a strong sensitivity of chamber response on positioning uncertainties, sometimes leading to dose uncertainties of 15 %.

Tantot, L.; Seuntjens, J.

2008-02-01

213

Modelling of pulverised wood combustion using a functional group model  

Microsoft Academic Search

Modelling of pulverised wood flames in a laboratory vertical furnace was carried out. The aim was to gain deeper understanding of the combustion process and to validate a mathematical model to simulate the process. Pulverised wood combustion involves many different processes such as two-phase flow dynamics, drying and devolatilisation of the particles, oxidation of the volatile and formation and oxidation

A. Elfasakhany; T. Klason; X. S. Bai

2008-01-01

214

Analysis and flamelet modelling for spray combustion  

NASA Astrophysics Data System (ADS)

The validity of a steady-flamelet model and a flamelet/progress-variable approach for gaseous and spray combustion is investigated by a two-dimensional direct numerical simulation (DNS) of gaseous and spray jet flames, and the combustion characteristics are analysed. A modified flamelet/progress-variable approach, in which total enthalpy rather than product mass fraction is chosen as a progress variable, is also examined. DNS with an Arrhenius formation, in which the chemical reaction is directly solved in the physical flow field, is performed as a reference to validate the combustion models. The results show that the diffusion flame is dominant in the gaseous diffusion jet flame, whereas diffusion and premixed flames coexist in the spray jet flame. The characteristics of the spray flame change from premixed-diffusion coexistent to diffusion-dominant downstream. Comparisons among the results from DNS with various combustion models show the modified flamelet/progress-variable approach to be superior to the other combustion models, particularly for the spray flame. Where the behaviour of the gaseous total enthalpy is strongly affected by the energy transfer (i.e. heat transfer and mass transfer) from the dispersed droplet, and this effect can be accounted for only by solving the conservation equation of the total enthalpy. However, even the DNS with the modified flamelet/progress-variable approach tends to underestimate the gaseous temperature in the central region of the spray jet flame. To increase the prediction accuracy, a combustion model for the partially premixed flame for the spray flame is necessary.

Baba, Yuya; Kurose, Ryoichi

215

Some remarks on modeling CSTR combustion processes  

SciTech Connect

Simulation of CSTR combustion experiments by means of numerical modeling has recently started to appear in the literature. In order to give a methodological contribution to the development of such models, the authors highlight the main problems that, in their opinion, should be tackled. Correct derivation of energy balance and its effects on simulation of dynamic behavior of combustion processes are discussed. The role played by flow characteristics of the reactor exhaust, by assumed initial conditions and by the usual simplifying assumptions, is presented by means of numerical experiments. The necessity of devising appropriate numerical procedures to overcome the problems arising from the multiplicity of states expected from the nonlinearity of the process is also stressed. Results of numerical experiments are obtained, as an example, on the basis of a kinetic scheme for the combustion of acetaldehyde at low temperatures.

Lignola, P.G.; DiMaio, F.P. (Dept. of Chemistry, Univ. of Calabria (IT))

1990-06-01

216

Biomass downdraft gasifier with internal cyclonic combustion chamber: Design, construction, and experimental results  

Microsoft Academic Search

An exploratory downdraft gasifier design with unique biomass pyrolysis and tar cracking mechanism is evolved at Oklahoma State University. This design has an internal separate combustion section where turbulent, swirling high-temperature combustion flows are generated. A series of research trials were conducted using wood shavings as the gasifier feedstock. Maximum tar cracking temperatures were above 1100°C. Average volumetric concentration levels

Krushna Patil; Prakash Bhoi; Raymond Huhnke; Danielle Bellmer

2011-01-01

217

Effect of Chamber Pressurization Rate on Combustion and Propagation of Solid Propellant Cracks  

Microsoft Academic Search

area of the propellant grain satisfies the designed value. But cracks in propellant grain can be generated during manufacture, storage, handing and so on. The cracks can provide additional surface area for combustion. The additional combustion may significantly deviate the performance of the rocket motor from the designed conditions, even lead to explosive catastrophe. Therefore a thorough study on the

Wei-Lan Yuan; Shen Wei; Shu-Shen Yuan

2002-01-01

218

THEORETICAL INVESTIGATION OF THE PERFORMANCE OF ALTERNATIVE AVIATION FUELS IN AN AERO-ENGINE COMBUSTION CHAMBER  

Microsoft Academic Search

When considering alternative fuels for aviation, factors such as the overall efficiency of the combustion process and the levels of emissions emitted to the atmosphere, need to be critically evaluated. The physical and chemical properties of a fuel influence the combustion efficiency and emissions and therefore need to be considered. The energy content of a biofuel, which is influenced negatively

I. Uryga; M. Pourkashanian; D. Borman; E. Catalanotti; C. W. Wilson

2009-01-01

219

Method of improving the combustion of fuel containing hydrocarbon compounds in the combustion chamber or chambers of internal combustion engines, and a liquid composition for carrying the method into effect  

Microsoft Academic Search

For the improved combustion of hydrocarbon compounds, for example those contained in gasoline, diesel fuel etc., in internal combustion engines a liquid composition comprising hydrogen peroxide, water, aliphatic alcohol having 1-4 carbon atoms, and preferably thin lubricating oil and anticorrosive is admixed with the fuel air mixture in the internal combustion engines.

T. N. Anderberg; A. Mellovist

1982-01-01

220

Method and apparatus for igniting a combustible mixture, especially gasoline-air in the combustion chamber of an internal combustion engine  

SciTech Connect

In an internal combustion engine, an apparatus is described for igniting a combustible fuel-air mixture within the combustion space of the cylinder of the combustion engine. The engine comprises: a sparkplug having spark electrodes located in the combustion space; ignition spark generating apparatus coupled to the sparkplug; and means to enhance energy output from the sparkplug for ignition during the breakdown phase of sparking of the sparkplug comprising means for sensing air quantity being supplied to the engine and for providing an air quantity signal; means for sensing fuel quantity being supplied to the engine and for providing a fuel quantity signal; and a control unit controlling the number of breakdowns of spark flash-overs across electrodes of the sparkplug as a function of the output representative of the ratio of fuel to air.

Herden, W.

1987-03-31

221

Combustion modeling in advanced gas turbine systems  

SciTech Connect

Goal of DOE`s Advanced Turbine Systems program is to develop and commercialize ultra-high efficiency, environmentally superior, cost competitive gas turbine systems for base-load applications in utility, independent power producer, and industrial markets. Primary objective of the program here is to develop a comprehensive combustion model for advanced gas turbine combustion systems using natural gas (coal gasification or biomass fuels). The efforts included code evaluation (PCGC-3), coherent anti-Stokes Raman spectroscopy, laser Doppler anemometry, and laser-induced fluorescence.

Smoot, L.D.; Hedman, P.O.; Fletcher, T.H.; Brewster, B.S.; Kramer, S.K. [Brigham Young Univ., Provo, UT (United States). Advanced Combustion Engineering Research Center

1995-12-31

222

Spectral modeling of radiation in combustion systems  

Microsoft Academic Search

Radiation calculations are important in combustion due to the high temperatures encountered but has not been studied in sufficient detail in the case of turbulent flames. Radiation calculations for such problems require accurate, robust, and computationally efficient models for the solution of radiative transfer equation (RTE), and spectral properties of radiation. One more layer of complexity is added in predicting

Gopalendu Pal

2010-01-01

223

Modeling of CWM droplet combustion. Final report  

Microsoft Academic Search

The objective of the present study was to develop a one-dimensional, unsteady state model for coal-water mixture droplet combustion, and to compare the characteristic times for the various processes, such as water vaporization, devolatilization and char oxidation with available experimental data. A water film surrounding a spherical coal particle is considered to undergo vaporization by heat transfer from the hot

K. Pandalai; S. Aggarwal; W. Sirignano

1983-01-01

224

Recent progress in modeling solid propellant combustion  

Microsoft Academic Search

Tremendous progress has been achieved in the last ten years with respect to modeling the combustion of solid propellants.\\u000a The vastly increased performance of computing capabilities has allowed utilization of calculation approaches that were previously\\u000a only conceptual. The paper will discuss three areas of emphasis: first, numerical modeling of premixed flames using detailed\\u000a kinetic mechanisms; second, development of packing models

M. W. Beckstead

2006-01-01

225

Biomass downdraft gasifier with internal cyclonic combustion chamber: design, construction, and experimental results.  

PubMed

An exploratory downdraft gasifier design with unique biomass pyrolysis and tar cracking mechanism is evolved at Oklahoma State University. This design has an internal separate combustion section where turbulent, swirling high-temperature combustion flows are generated. A series of research trials were conducted using wood shavings as the gasifier feedstock. Maximum tar cracking temperatures were above 1100°C. Average volumetric concentration levels of major combustible components in the product gas were 22% CO and 11% H(2). Hot and cold gas efficiencies were 72% and 66%, respectively. PMID:21463935

Patil, Krushna; Bhoi, Prakash; Huhnke, Raymond; Bellmer, Danielle

2011-03-15

226

Fluids and Combustion Facility: Combustion Integrated Rack Modal Model Correlation.  

National Technical Information Service (NTIS)

The Fluids and Combustion Facility (FCF) is a modular, multi-user, two-rack facility dedicated to combustion and fluids science in the US Laboratory Destiny on the International Space Station. FCF is a permanent facility that is capable of accommodating u...

M. E. McNelis V. J. Suarez T. L. Sullivan K. D. Otten J. C. Akers

2005-01-01

227

Chemical Kinetic Modeling of Biofuel Combustion  

NASA Astrophysics Data System (ADS)

Bioalcohols, such as bioethanol and biobutanol, are suitable replacements for gasoline, while biodiesel can replace petroleum diesel. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This study's contribution is experimentally validated chemical kinetic combustion mechanisms for biobutanol and biodiesel. Fundamental combustion data and chemical kinetic mechanisms are presented and discussed to improve our understanding of biofuel combustion. The net environmental impact of biobutanol (i.e., n-butanol) has not been studied extensively, so this study first assesses the sustainability of n-butanol derived from corn. The results indicate that technical advances in fuel production are required before commercializing biobutanol. The primary contribution of this research is new experimental data and a novel chemical kinetic mechanism for n-butanol combustion. The results indicate that under the given experimental conditions, n-butanol is consumed primarily via abstraction of hydrogen atoms to produce fuel radical molecules, which subsequently decompose to smaller hydrocarbon and oxygenated species. The hydroxyl moiety in n-butanol results in the direct production of the oxygenated species such as butanal, acetaldehyde, and formaldehyde. The formation of these compounds sequesters carbon from forming soot precursors, but they may introduce other adverse environmental and health effects. Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents high quality experimental data for one large fatty acid methyl ester, methyl decanoate, and models its combustion using an improved skeletal mechanism. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which ultimately lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene. The study concludes that the oxygenated molecules in biofuels follow similar combustion pathways to the hydrocarbons in petroleum fuels. The oxygenated moiety's ability to sequester carbon from forming soot precursors is highlighted. However, the direct formation of oxygenated hydrocarbons warrants further investigation into the environmental and health impacts of practical biofuel combustion systems.

Sarathy, Subram Maniam

228

Combustion space modeling of an aluminum furnace  

SciTech Connect

Secondary aluminum production (melting from aluminum ingots, scraps, etc.) offers significant energy savings and environmental benefits over primary aluminum production since the former consumes only five percent of the energy used in the latter process. The industry, however, faces technical challenges of further improving furnace melting efficiency and has been lacking tools that can help understand combustion process in detail and that will facilitate furnace design. Computational Fluid Dynamics (CFD) modeling has played increasingly important roles in evaluating industrial processes. As part of a larger program run by SECAT, a CFD model has been developed at Argonne National Laboratory to simulate fuel combustion, heat transfer (including thermal radiation), gaseous product flow (mainly CO2 and H2O), and production/transport of pollutant species/greenhouse gases in an aluminum furnace. Using this code, the surface heat fluxes are calculated and then transferred to a melt code. In order to have a high level of confidence in the computed results, the output from the code will be compared and validated against in-furnace measurements made in the Albany furnace. Once validated, the combustion code may be used to perform inexpensive parametric studies to investigate methods to optimize furnace performance. This paper will present results from the combustion modeling of an aluminum furnace as well as results from several parametric studies.

Golchert, Brian M. (ANL); Zhou, C.Q. (Purdue University Calumet, Hammond, IN); Quenette, Antoine (ANL).; Han, Quinyou (ORNL).; King, Paul E.

2005-02-01

229

Advanced radiation techniques for inspection of diesel engine combustion chamber materials components. Final report.  

National Technical Information Service (NTIS)

Heavy duty truck engines must meet stringent life cycle cost and regulatory requirements. Meeting these requirements has resulted in convergence on 4-stroke 6-in-line, turbocharged, and after-cooled engines with direct-injection combustion systems. These ...

1995-01-01

230

Experimental and Numerical Investigations on Mixing and Combustion Processes in a Supersonic Model Combustor  

NASA Astrophysics Data System (ADS)

To improve the understanding of mixing and combustion processes in the investigated model combustor and deliver validation data for numerical simulations experiments on staged injection and combustion were conducted. The combustion chamber is integrated in a direct-connected test facility which offers the possibility of continuous operation. Within the first part of the combustion chamber the strut injector is located. In the divergent part of the chamber the eight interchangeable wall injectors are located, four on the lower wall and four on the upper wall. Wall injectors were chosen as second stage to exploit the unburnt oxygen close to the walls. To evaluate the combustor performance the wall pressure distribution was measured. Due to large windows within the sidewalls around 80% of the combustor is optically accessible. For the mixing studies helium was injected through the wall injectors and Schlieren images were taken to show the change in the shock system and evaluate the penetration depth. The test results were compared to three-dimensional numerical simulations using a commercial CFD-tool. Furthermore combustion tests with injection of gaseous hydrogen were conducted.

Fuhrmann, S.; Paukner, D.; Hupfer, A.; Kau, H.-P.

2011-08-01

231

Coupling conjugate heat transfer with in-cylinder combustion modeling for engine simulation  

Microsoft Academic Search

A conjugate formulation to predict heat conduction in the solid domain and spray combustion in the fluid domain was developed for multidimensional engine simulation. Heat transfer through the wall affects the combustion process in the cylinder and the thermal loading on the combustion chamber surface. To account for the temporal and spatial variations of temperature on the chamber surface, a

Yuanhong Li; Song-Charng Kong

2011-01-01

232

Mathematical model of chalcocite particle combustion  

Microsoft Academic Search

A mathematical model has been developed to simulate the combustion of a single chalcocite particle (particle diameter between\\u000a 10 and 100 microns) in air, oxygen, and oxygen-SO2 mixtures. Neglecting temperature and composition gradients within the particle, the model computes the thermal and compositional\\u000a changes of the particle as a function of time. Five chemical reactions were considered to describe the

A. A. Shook; G. G. Richards; J. K. Brimacombe

1995-01-01

233

Visualization of Gas-to-Liquid (GTL) Fuel Liquid Length and Soot Formation in the Constant Volume Combustion Chamber  

NASA Astrophysics Data System (ADS)

In this research, GTL spray combustion was visualized in an optically accessible quiescent constant-volume combustion chamber. The results were compared with the spray combustion of diesel fuel. Fast-speed photography with direct laser sheet illumination was used to determine the fuel liquid-phase length, and shadowgraph photography was used to determine the distribution of the sooting area in the fuel jet. The results showed that the fuel liquid-phase length of GTL fuel jets stabilized at about 20-22mm from the injector orifice and mainly depended on the ambient gas temperature and fuel volatility. GTL had a slightly shorter liquid length than that of the diesel fuel. This tendency was also maintained when multiple injection strategy was applied. The penetration of the tip of the liquid-phase fuel during pilot injection was a little shorter than the penetration during main injection. The liquid lengths during single and main injections were identical. In the case of soot formation, the results showed that soot formation was mainly affected by air-fuel mixing, and had very weak dependence on fuel volatility.

Azimov, Ulugbek; Kim, Ki-Seong

234

An extended multi-zone combustion model for PCI simulation  

Microsoft Academic Search

Novel combustion modes are becoming an important area of research with emission regulations more stringent than ever before, and with fuel economy being assigned greater importance every day. Homogeneous Charge Compression Ignition (HCCI) and Premixed Compression Ignition (PCI) modes in particular promise better fuel economy and lower emissions in internal combustion engines.Multi-zone combustion models have been popular in modelling HCCI

Janardhan Kodavasal; Seunghwan Keum; Aristotelis Babajimopoulos

2011-01-01

235

On mathematical modelling of flameless combustion  

Microsoft Academic Search

A further analysis of the IFRF semi-industrial-scale experiments on flameless (mild) combustion of natural gas is carried out. The experimental burner features a strong oxidizer jet and two weak natural gas jets. Numerous publications have shown the inability of various RANS-based mathematical models to predict the structure of the weak jet. We have proven that the failure is in error

Marco Mancini; Patrick Schwoeppe; Roman Weber; Stefano Orsino

2007-01-01

236

On mathematical modelling of flameless combustion  

SciTech Connect

A further analysis of the IFRF semi-industrial-scale experiments on flameless (mild) combustion of natural gas is carried out. The experimental burner features a strong oxidizer jet and two weak natural gas jets. Numerous publications have shown the inability of various RANS-based mathematical models to predict the structure of the weak jet. We have proven that the failure is in error predictions of the entrainment and therefore is not related to any chemistry submodels, as has been postulated. (author)

Mancini, Marco; Schwoeppe, Patrick; Weber, Roman [IEVB Institute, Clausthal University of Technology (Germany); Orsino, Stefano [Fluent Inc., Lebanon (United States)

2007-07-15

237

Optical Studies of Combustion Chamber Flame in a Hybrid Rocket Motor  

Microsoft Academic Search

The oxygen injector head in UALR's labscale hybrid rocket motor has been redesigned to in- clude a coaxially located optical port. This port permits viewing directly into the space in front of the fuel grain where combustion is initiated. It is designed to allow a visible-imaging fiber optic, a UV-Vis fiber optic, or an infrared fiber optic to be aligned

Andrew B. Wright; Jason E. Elsasser; M. Keith Hudson; Ann M. Wright

238

LDV measurements of the flow inside the combustion chamber of a 4-valve D.I. diesel engine with axisymmetric piston-bowls  

NASA Astrophysics Data System (ADS)

LDV measurements of the tangential and radial velocity components have been performed to investigate the flow patterns inside a 4-valve single cylinder diesel engine for various engine speeds, swirl numbers and piston-bowl geometries, under conditions similar to those of a production engine. The work focused on the near-wall region of the axisymmetric combustion chambers where the strong swirl-squish and spray-wall interactions take place. The different axial flow stratification observed in both velocity components has confirmed the influence of piston shape and intake configuration on the flow patterns and turbulence levels near compression TDC. Measured values are in reasonable agreement with those provided by a two-zone phenomenological model.

Payri, F.; Desantes, J. M.; Pastor, J. V.

1996-12-01

239

A GENERALIZED MODEL OF ACOUSTIC RESPONSE OF TURBULENT PREMIXED FLAME AND ITS APPLICATION TO GAS-TURBINE COMBUSTION INSTABILITY ANALYSIS  

Microsoft Academic Search

An analytical model is developed to study the combustion response of turbulent premixed flames to acoustic oscillations. The analysis is based on a level-set flamelet model, and accommodates spatial variations in chamber geometry and mean-flow properties. All known factors affecting the flame response to local flow disturbances are analyzed. A triple decomposition technique, which expresses each flow variable as the

DANNING YOU; YING HUANG; VIGOR YANG

2005-01-01

240

Fuel combustion system and method of operation for an Otto-cycle internal combustion engine  

Microsoft Academic Search

This paper describes a method of combusting a predetermined combustible mixture of fuel and air in an Otto-cycle internal combustion engine including a main combustion chamber, first control valve means for admitting the combustible mixture into the main combustion chamber, an auxiliary combustion chamber, second control valve means for opening and blocking fluid communication between the main combustion chamber and

Bailey

1991-01-01

241

Spark Ignition and PreChamber Turbulent Jet Ignition CombustionVisualization  

Microsoft Academic Search

Natural gas is a promising alternative fuel as it is affordable, available\\u000d\\u000a\\u0009worldwide, has high knock resistance and low carbon content. This\\u000d\\u000a\\u0009study focuses on the combustion visualization of spark ignition combustion\\u000d\\u000a\\u0009in an optical single cylinder engine using natural gas at several\\u000d\\u000a\\u0009air to fuel ratios and speed-load operating points. In addition,\\u000d\\u000a\\u0009Turbulent Jet Ignition optical images are compared

William P. Attard; Elisa Toulson; Andrew Huisjen; XuefeiChen; Guoming Zhu; Harold Schock

2012-01-01

242

Principle of soft x-ray Moire deflectometry for flow-field visualization in a diesel combustion chamber  

NASA Astrophysics Data System (ADS)

The technique based on Moire deflectometry with soft x-ray laser beam has been demonstrated by the research group of D. Ress in the research of plasma produced by laser. We apply this method to visualize the flow field in diesel combustion chamber, and it is also a new application in the world. When a beam of collimated light passes through the flow field, the index-of-refraction gradient in the plasma bends the rays through an angle. A Moire pattern is created when a probe beam is passed through a pair of rotationally offset (angle (theta) ) 1D rulings consisting of evenly spaced opaque and transmissive stripes. By measuring the fringe shift we can get the information of flow field.

You, Haihang; Yan, Dapeng; Wang, Zhengdong; He, Anzhi

1997-10-01

243

Ongoing development of a low-emission industrial gas turbine combustion chamber  

Microsoft Academic Search

Experiments performed on laboratory- and full-scale gas-turbine combustors to test the feasibility of meeting proposed federal emission standards demonstrated that by uniformly mixing gaseous fuel and primary-zone air prior to combustion and burning the fuel leanly (equivalence ratio <1.0), an industrial gas turbine could meet the proposed emission standards. The characteristic narrow range of flame stability obtained with lean premix

V. M. Sood; J. R. Shekleton

1980-01-01

244

Finite difference seismic modeling of axial magma chambers  

NASA Astrophysics Data System (ADS)

We tested the feasibility of using finite difference methods to model seismic propagation at ˜10 Hz through a two-dimensional representation of an axial magma chamber with a thin, liquid lid. Our technique produces time series of displacement or pressure at seafloor receivers to mimic a seismic refraction experiment and snapshots of P and S energy propagation. The results indicate that our implementation is stable for models with sharp velocity contrasts and complex geometries. We observe a high-energy, downward-traveling shear phase, observable only with borehole receivers, that would be useful in studying the nature and shape of magma chambers. The ability of finite difference methods to model high-order wave phenomena makes this method ideal for testing velocity models of spreading axes and for planning near-axis drilling of the East Pacific Rise in order to optimize the benefits from shear wave imaging of sub-axis structure.

Swift, Stephen A.; Dougherty, Martin E.; Stephen, Ralph A.

1990-11-01

245

Stove with multiple chambers  

SciTech Connect

A stove is described for burning a solid fuel such as wood. The wall means defines a main air inlet, a combustion gas outlet, and four chambers through which gas passes sequentially from the main air inlet to the combustion gas outlet. The chambers comprises a pre-heat plenum chamber into which the main air inlet opens. A main combustion chamber contains solid fuel to be burned into which gas passes from the pre-heat plenum chamber, a second combustion chamber which is downstream of the main combustion chamber with respect to the flow of gas from the main air inlet to the combustion gas outlet, and a third combustion chamber from which the combustion gas outlet opens. The stove also comprises a plate having a restricted opening for providing communication between the second and third combustion chambers. And a catalytic converter comprises a body of solid material formed with passageways, the body of solid material being fitted in the restricted opening so that gas passes from the second combustion chamber to the third combustion chamber by way of the passageways in the body.

Black, A.

1987-04-21

246

Convergence of a finite difference method for combustion model problems  

Microsoft Academic Search

We study a finite difference scheme for a combustion model problem. A projection scheme near the combustion wave, and the\\u000a standard upwind finite difference scheme away from the combustion wave are applied. Convergence to weak solutions with a combustion\\u000a wave is proved under the normal Courant-Friedrichs-Lewy condition. Some conditions on the ignition temperature are given to\\u000a guarantee the solution containing

Long’an Ying

2004-01-01

247

Hydrocarbon-fuel\\/combustion-chamber-liner materials compatibility. Final Report, 31 Oct. 1989 - 31 Mar. 1991  

Microsoft Academic Search

The results of dynamic tests using methane and NASA-Z copper test specimen under conditions that simulate those expected in the cooling channels of a regeneratively cooled LOX\\/hydrocarbon booster engine operating at chamber pressures up to 3000 psi are presented. Methane with less than 0.5 ppm sulfur contamination has little or no effect on cooling channel performance. At higher sulfur concentrations,

Homer

1991-01-01

248

Comparison of different combustion models in enclosure fire simulation  

Microsoft Academic Search

In this study, three combustion models, the volumetric heat source (VHS) model, the eddy break-up model and the presumed probability density function (prePDF) model, are examined in enclosure fire simulation. The combustion models are compared and evaluated for their performance in predicting three typical enclosure fires, a room fire, a shopping mall fire and a tunnel fire. High Reynolds number

H. Xue; J. C. Ho; Y. M. Cheng

2001-01-01

249

Direct heat loss to combustion chamber walls in a direct-injection diesel engine: Evaluation of direct heat loss to piston and cylinder head  

Microsoft Academic Search

The purpose of this study is to clarify the state of the heat loss in a direct-injection diesel engine. Originally developed thin-film thermocouples (TFTs) are embedded into the combustion chamber walls for accurate measurement of instantaneous surface temperature from which instantaneous heat flux is evaluated through the heat conduction equation. Measured points are arrayed on the cavity bottom, the cavity

Y Suzuki; K Shimano; Y Enomoto; M Emi; Y Yamada

2005-01-01

250

Modelling of Sulphur Dioxide Capture in Fluidized Bed Combustion.  

National Technical Information Service (NTIS)

The paper discusses the relation between SO2 models and comprehensive fluidized bed models. By comprehensive models is here meant complex models treating the hydrodynamics and combustion reactions in a fluidized bed. SO2 models can be both independent mod...

A. Lyngfelt

1989-01-01

251

Simplified combustion modeling of composite propellants  

NASA Astrophysics Data System (ADS)

A two-dimensional, steady state model of a burning composite propellant is developed to study the characteristics of the combustion process. The solid composite is a periodic sandwich unit comprised of two oxidizer laminates separated by a fuel binder layer. Included in the model are essential features for simulating composite propellant combustion: (1) a free surface boundary, (2) gas- and condensed-phase heat release distributions based on simplified chemical kinetics, and (3) an implicit surface regression rate (unique burning rate) determined by coupled gas-solid energy/species transport analysis. Comparisons of the model with experimental observations focus on surface geometry, flame structure and the burning rate for variations in pressure, particle size, binder width and propellant formulation. Experimentally observed trends for typical composite propellants are replicated. For example, the relative protrusion/recession of oxidizer and binder, recognized as an important feature of propellant surface topography, is correctly predicted. The simulation demonstrates the relation between gas-phase heat release and the heat-feedback driving the solid phase pyrolysis. This information is critical to predicting surface geometry and regression rate. Success was also achieved in predicting the experimental burning rate pressure sensitivity without the use of arbitrary non-integer reaction orders. The model provides a framework for future studies with more complex kinetic mechanisms, transient phenomena, and three-dimensional particulate propellants.

Knott, Gregory Matthew

2001-10-01

252

Turbulent Diffusion Combustion Model Using Chemical Equilibrium Combined with the Eddy Dissipation Model for Simple Prediction of Combustion Products  

Microsoft Academic Search

This research aims at building a turbulent diffusion combustion model based on chemical equilibrium and kinetics for simplifying complex chemical mechanisms. This paper presents the combustion model based on the chemical equilibrium combined with an eddy dissipation model; this model is validated by simulating a H2-air turbulent diffusion flame. In this model, the reaction rate of fuels is estimated by

Kazui Fukumoto; Akihito Sakai; Yoshifumi Ogami

2010-01-01

253

Combustion Model for a CFB Boiler with Consideration of Post-Combustion in the Cyclone  

NASA Astrophysics Data System (ADS)

Severe post combustion in the cyclone of CFB boilers could destroy heat absorbing balance among the heating surfaces and cause overheating problem for reheaters and superheaters. However, post combustion in the cyclone is rarely considered in the design phase of a CFB boiler. Based on our previous experiment results, group combustion model is used in this study to estimate the combustion of particles in the cyclone. It is found that the combustion of particles in the cyclone did not contribute as much as we anticipated to the temperature augment in the cyclone because of great oxygen diffusion resistance in near-wall particle layer. Post combustion model in the cyclone is then added into a one-dimensional combustion model of CFB boiler, in which the gas-solid flow, reaction, and heat absorption at different vertical locations in a CFB boiler can be well predicted with the knowledge of operation parameters. The new model was used to estimate the influence of some operation parameters on the post combustion in the cyclone and heat releasing fraction in the cyclone. The prediction results are very good.

Li, S. H.; Yang, H. R.; Zhang, H.; Wu, Y. X.; Lu, J. F.; Yue, G. X.

254

Realistic modeling of chamber transport for heavy-ion fusion  

SciTech Connect

Transport of intense heavy-ion beams to an inertial-fusion target after final focus is simulated here using a realistic computer model. It is found that passing the beam through a rarefied plasma layer before it enters the fusion chamber can largely neutralize the beam space charge and lead to a usable focal spot for a range of ion species and input conditions.

Sharp, W.M.; Grote, D.P.; Callahan, D.A.; Tabak, M.; Henestroza, E.; Yu, S.S.; Peterson, P.F.; Welch, D.R.; Rose, D.V.

2003-05-01

255

Experimental designs and emission rate modeling for chamber experiments  

NASA Astrophysics Data System (ADS)

This paper considers some of the statistical aspects of estimating specimen emission rate profiles from chamber concentration level measurements, which is a major step in assessing indoor pollution levels. Parametric and nonparametric modeling approaches are applied to the problem, and their relative advantages and disadvantages are discussed. The issue of experimental design is also addressed, and the choice of an optimal set of experimental conditions and sampling times is considered. Some simulation results are presented to contrast the efficiencies of various experimental designs.

Hayter, Anthony J.; Dowling, Mary M.

256

Analysis of the Effect of Geometry Generated Turbulence on HCCI Combustion by Multi-Zone Modeling  

SciTech Connect

This paper illustrates the applicability of a sequential fluid mechanics, multi-zone chemical kinetics model to analyze HCCI experimental data for two combustion chamber geometries with different levels of turbulence: a low turbulence disc geometry (flat top piston), and a high turbulence square geometry (piston with a square bowl). The model uses a fluid mechanics code to determine temperature histories in the engine as a function of crank angle. These temperature histories are then fed into a chemical kinetic solver, which determines combustion characteristics for a relatively small number of zones (40). The model makes the assumption that there is no direct linking between turbulence and combustion. The results show that the multi-zone model yields good results for both the disc and the square geometries. The model makes good predictions of pressure traces and heat release rates. The experimental results indicate that the high turbulence square geometry has longer burn duration than the low turbulence disc geometry. This difference can be explained by the sequential multi-zone model, which indicates that the cylinder with the square bowl has a thicker boundary layer that results in a broader temperature distribution. This broader temperature distribution tends to lengthen the combustion, as cold mass within the cylinder takes longer to reach ignition temperature when compressed by the expansion of the first burned gases. The multi-zone model, which makes the basic assumption that HCCI combustion is controlled by chemical kinetics, is therefore capable of explaining the experimental results obtained for different levels of turbulence, without considering a direct interaction between turbulence and combustion. A direct connection between turbulence and HCCI combustion may still exists, but it seems to play a relatively minor role in determining burn duration at the conditions analyzed in this paper.

Aceves, S M; Flowers, D L; Martinez-Frias, J; Espinosa-Loza, F; Christensen, M; Johansson, B; Hessel, R P

2004-12-13

257

NOX EMISSIONS MODELING IN BIOMASS COMBUSTION GRATE FURNACES  

Microsoft Academic Search

A new flamelet combustion model is developed for the modeling of NOx emissions in biomass grate furnaces. The model describes the combustion chemistry using premixed flamelets. The chemical system is mapped on two controlling variables: the mixture fraction and a reaction progress variable. The species mass fractions and temperature are tabulated as functions of the controlling variables in a pre-processing

B. A. Albrecht; R. J. M. Bastiaans; J. A. van Oijen; L. P. H. de Goey

258

Kinetic model for nitric oxide formation during pulverized coal combustion  

Microsoft Academic Search

A mathematical model of NO formation during pulverised coal combustion was developed from a proposed kinetic mechanism involving 12 overall chemical reactions. Most significantly, the model describes the complex conversion of coal bound nitrogen compounds to NO during combustion. The predictions of the model compare favourably with literature data and are in qualitative agreement with trends observed in practical coal

J. W. Mitchell; J. M. Tarbell

1982-01-01

259

Vaporized liquid fuel combustion apparatus  

Microsoft Academic Search

This patent describes a vaporized liquid fuel combustion apparatus comprising: a cylinder defining a combustion chamber, the cylinder having an inlet end for receipt of combustion air, a first flange surrounding the inlet end and an outlet end for exhausting gaseous combustion products; means for introducing the fuel into the combustion chamber and ignition means exposed to the combustion chamber

Y. Kimijima; K. Kikuchi

1986-01-01

260

Sub-grid scale combustion models for large eddy simulation of unsteady premixed flame propagation around obstacles.  

PubMed

In this work, an assessment of different sub-grid scale (sgs) combustion models proposed for large eddy simulation (LES) of steady turbulent premixed combustion (Colin et al., Phys. Fluids 12 (2000) 1843-1863; Flohr and Pitsch, Proc. CTR Summer Program, 2000, pp. 61-82; Kim and Menon, Combust. Sci. Technol. 160 (2000) 119-150; Charlette et al., Combust. Flame 131 (2002) 159-180; Pitsch and Duchamp de Lageneste, Proc. Combust. Inst. 29 (2002) 2001-2008) was performed to identify the model that best predicts unsteady flame propagation in gas explosions. Numerical results were compared to the experimental data by Patel et al. (Proc. Combust. Inst. 29 (2002) 1849-1854) for premixed deflagrating flame in a vented chamber in the presence of three sequential obstacles. It is found that all sgs combustion models are able to reproduce qualitatively the experiment in terms of step of flame acceleration and deceleration around each obstacle, and shape of the propagating flame. Without adjusting any constants and parameters, the sgs model by Charlette et al. also provides satisfactory quantitative predictions for flame speed and pressure peak. Conversely, the sgs combustion models other than Charlette et al. give correct predictions only after an ad hoc tuning of constants and parameters. PMID:20471163

Di Sarli, Valeria; Di Benedetto, Almerinda; Russo, Gennaro

2010-03-09

261

Chemical Kinetic Models for HCCI and Diesel Combustion  

SciTech Connect

Hydrocarbon fuels for advanced combustion engines consist of complex mixtures of hundreds or even thousands of different components. These components can be grouped into a number of chemically distinct classes, consisting of n-paraffins, branched paraffins, cyclic paraffins, olefins, oxygenates, and aromatics. Biodiesel contains its own unique chemical class called methyl esters. The fractional amounts of these chemical classes are quite different in gasoline, diesel fuel, oil-sand derived fuels and bio-derived fuels, which contributes to the very different combustion characteristics of each of these types of combustion systems. The objectives of this project are: (1) Develop detailed chemical kinetic models for fuel components used in surrogate fuels for diesel and HCCI engines; (2) Develop surrogate fuel models to represent real fuels and model low temperature combustion strategies in HCCI and diesel engines that lead to low emissions and high efficiency; and (3) Characterize the role of fuel composition on low temperature combustion modes of advanced combustion engines.

Pitz, W J; Westbook, C K; Mehl, M

2008-10-30

262

Hydrocarbon-fuel/combustion-chamber-liner materials compatibility. Final Report, 31 Oct. 1989 - 31 Mar. 1991  

SciTech Connect

The results of dynamic tests using methane and NASA-Z copper test specimen under conditions that simulate those expected in the cooling channels of a regeneratively cooled LOX/hydrocarbon booster engine operating at chamber pressures up to 3000 psi are presented. Methane with less than 0.5 ppm sulfur contamination has little or no effect on cooling channel performance. At higher sulfur concentrations, severe corrosion of the NASA-Z copper alloy occurs and the cuprous sulfide Cu{sub 2}S, thus formed impedes mass flow rate and heat transfer efficiency. Therefore, it is recommended that the methane specification for this end use set the allowable sulfur content at 0.5 ppm (max). Bulk high purity liquid methane that meets this low sulfur requirement is currently available from only one producer. Pricing, availability, and quality assurance are discussed in detail. Additionally, it was found that dilute sodium cyanide solutions effectively refurbish sulfur corroded cooling channels in only 2 to 5 minutes by completely dissolving all the Cu{sub 2}S. Sulfur corroded/sodium cyanide refurbished channels are highly roughened and the increased surface roughness leads to significant improvements in heat transfer efficiency with an attendant loss in mass flow rate. Both the sulfur corrosion and refurbishment effects are discussed in detail.

Homer, G.D.

1991-04-01

263

Search engine optimising elements and their effect on Website visibility: implementation of the Chambers model  

Microsoft Academic Search

The primary objective of this research project was to determine whether Search Engine Optimisation (SEO) elements, as identified in the Chambers model, affect website visibility. A full literature review was done on SEO, as well as an evaluation of the Chambers model. Secondly, empirical work has been done to determine whether or not the implementation of the Chambers model have

EB Visser; WT Kritzinger; M Weideman

264

Numerical Investigation of Combustion Induced Flame Flashback in a Premixed Combustion System  

Microsoft Academic Search

The flashback type known as combustion induced vortex breakdown of a modern premixed gas turbine combustion chamber was simulated numerically. The uRANS simulation technique was applied to capture the instantaneous behavior of the unisotropic flow field. An extended formulation of a flame surface density model was developed and utilized for combustion modeling. In addition, the dependency of the laminar flamelets

T. Voigt; P. Habisreuther; N. Zarzalis

2009-01-01

265

Analysis of the injection process in direct injected natural gas engines. Part 2: Effects of injector and combustion chamber design  

SciTech Connect

A study of natural gas (NG) direct injection (DI) processes in engines has been performed using multidimensional computational fluid dynamics analysis. The purpose was to investigate the effects of key engine design parameters on the mixing in DI NG engines. Full three-dimensional calculations of injection into a medium heavy-duty diesel engine cylinder were performed. Perturbations on a baseline engine configuration were considered. In spite of single plume axisymmetric injection calculations that show mixing improves as nozzle hole size is reduced: plume merging caused by having too many nozzle holes has a severe negative impact on mixing; and increasing the number of injector holes strengthens plume deflection toward the cylinder head, which also adversely affects mixing. The optimal number of holes for a quiescent engine was found to be that which produces the largest number of separate NG plumes. Increasing the nozzle angle to reduce plume deflection can adversely affect mixing due to reduced jet radial penetration. Increasing the injector tip height is an effective approach to eliminating plume deflection and improving mixing. Extremely high-velocity squish flows, with penetration to the center of the piston bowl, are necessary to have a significant impact on mixing. Possible improvements in mixing can be realized by relieving the center of the piston bowl in typical Mexican hat bowl designs. CFD analysis can effectively be used to optimize combustion chamber geometry by fitting the geometry to computed plume shapes.

Jennings, M.J.; Jeske, F.R. (Ricardo North America, Burr Ridge, IL (United States))

1994-10-01

266

SHS-system combustion models accounting for macrostructural transformations  

NASA Astrophysics Data System (ADS)

Based on the concepts of the mechanics of heterogeneous media, combustion models were constructed that take into account macrostructural transformations associated with liquid-phase sintering, the loosening action of gas filtering in the pores, and the difference in the densities of the initial substances and products. The combustion of systems with a partially gaseous product is investigated analytically. The rate of combustion and final porosity as well as the conditions for the formation of cracks are determined.

Smolyakov, V. K.

1993-10-01

267

Observing and modeling nonlinear dynamics in an internal combustion engine  

Microsoft Academic Search

We propose a low-dimensional, physically motivated, nonlinear map as a model for cyclic combustion variation in spark-ignited internal combustion engines. A key feature is the interaction between stochastic, small-scale fluctuations in engine parameters and nonlinear deterministic coupling between successive engine cycles. Residual cylinder gas from each cycle alters the in-cylinder fuel-air ratio and thus the combustion efficiency in succeeding cycles.

C. S. Daw; M. B. Kennel; C. E. Finney; F. T. Connolly

1998-01-01

268

Rotary internal combustion engine  

SciTech Connect

This patent describes an internal combustion engine comprising; a rotary compressor mechanism; a rotary expander mechanism; and combustion chamber means disposed between the compressor mechanism and the expander mechanism, whereby compressed air is delivered to the combustion chamber through the compressor discharge port, and pressurized gas is delivered from the combustion chamber into the expander mechanism through the pressurized gas intake port.

Le, L.K.

1990-11-20

269

Pulse combustion apparatus  

Microsoft Academic Search

A pulse combustion apparatus is described which includes: a combustion chamber; an exhaust system including an exhaust pipe forming a resonant system with the combustion chamber and a generally cylindrical exhaust cushion chamber downstream of the exhaust pipe for receiving combustion gases from the pipe and communicating with an exhaust outlet form the apparatus; means for delivering successive fuel charges

Kitchen

1986-01-01

270

A steady-state combustion modelling of composite solid propellants  

Microsoft Academic Search

By depicting the transfer of heat and combustion reaction to take place within thin gas layers close to the propellant surface\\u000a burning in a steady-state fashion, a mathematical equation has been deduced to describe the burning rate of solid propellant\\u000a as a function of initial grain temperature and chamber pressure. It has been also assumed that chemical reaction could take

Byung-Ki Hurt; Chong-Bo Kim

2001-01-01

271

Modeling of CWM droplet combustion. Final report  

SciTech Connect

The objective of the present study was to develop a one-dimensional, unsteady state model for coal-water mixture droplet combustion, and to compare the characteristic times for the various processes, such as water vaporization, devolatilization and char oxidation with available experimental data. A water film surrounding a spherical coal particle is considered to undergo vaporization by heat transfer from the hot air. After the water vaporization is complete, devolatilization begins. This process is assumed to be kinetically controlled. Water vaporization and devolatilization processes are modeled by using a hybrid Eulerian-Lagrangian method to obtain the properties of the gas-phase and the condensed-phase. An explicit finite difference scheme is used to solve the Eulerian gas-phase equation where as a Runga-Kutta scheme is employed to solve the Lagrangian condensed-phase equations. The predicted characteristic times for water vaporization is in good agreement with values proposed in the literature. At the present time there is insufficient data to draw any conclusions on the model. Methods are proposed to refine the simple kinetic model which takes into account pore diffusion and mass transfer for devolatilization and char oxidation. 9 references, 12 figures.

Pandalai, K.; Aggarwal, S.; Sirignano, W.

1983-10-01

272

Simulations of Turbulent Spray Combustion in a Constant-Volume Chamber for Diesel-Engine-Like Conditions  

NASA Astrophysics Data System (ADS)

In-cylinder aero-thermal-chemical processes in piston engines are rich and complex, and modern engines are already at a high level of refinement. Further increases in performance, reductions in fuel consumption and emissions, and accommodation of nontraditional fuels will require the effective use of high-spatial-and-temporal-resolution optical diagnostics and numerical simulations. In this research, computational fluid dynamics tools are being developed to explore the influences of fuel properties on autoignition, combustion, and pollutant emissions in compression-ignition engines. The modeling includes a transported probability density function method to account for turbulent fluctuations in composition and temperature, detailed soot models with a method of moments for soot aerosol dynamics, a stochastic photon Monte Carlo method for participating-medium radiation heat transfer, and line-by-line spectral properties for mixtures of molecular gases and soot. The models are applied to a constant-volume spray combustion bomb where measurements are available for a range of thermochemical conditions and for a variety of fuels. Parametric studies of the influences of key physical and numerical parameters are performed to determine sensitivities and to establish best practices to be carried forward into subsequent modeling studies of real engines.

Zhang, H.; Haworth, D. C.

2010-11-01

273

A combustion model for IC engine combustion simulations with multi-component fuels  

SciTech Connect

Reduced chemical kinetic mechanisms for the oxidation of representative surrogate components of a typical multi-component automotive fuel have been developed and applied to model internal combustion engines. Starting from an existing reduced mechanism for primary reference fuel (PRF) oxidation, further improvement was made by including additional reactions and by optimizing reaction rate constants of selected reactions. Using a similar approach to that used to develop the reduced PRF mechanism, reduced mechanisms for the oxidation of n-tetradecane, toluene, cyclohexane, dimethyl ether (DME), ethanol, and methyl butanoate (MB) were built and combined with the PRF mechanism to form a multi-surrogate fuel chemistry (MultiChem) mechanism. The final version of the MultiChem mechanism consists of 113 species and 487 reactions. Validation of the present MultiChem mechanism was performed with ignition delay time measurements from shock tube tests and predictions by comprehensive mechanisms available in the literature. A combustion model was developed to simulate engine combustion with multi-component fuels using the present MultiChem mechanism, and the model was applied to simulate HCCI and DI engine combustion. The results show that the present multi-component combustion model gives reliable performance for combustion predictions, as well as computational efficiency improvements through the use of reduced mechanism for multi-dimensional CFD simulations. (author)

Ra, Youngchul; Reitz, Rolf D. [Engine Research Center, University of Wisconsin-Madison (United States)

2011-01-15

274

Influence of resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion  

NASA Astrophysics Data System (ADS)

The influence of acoustic resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion was experimentally examined. In the study, resonators having identical throats and different cavity diameters were used. For fixed-volume resonators the best propulsion performance characteristics were achieved in the case in which the cavity diameter differed little from the resonator throat diameter.

Potapkin, A. V.; Moskvichev, D. Yu.

2008-09-01

275

LDV measurements of the flow inside the combustion chamber of a 4-valve D.I. diesel engine with axisymmetric piston-bowls  

Microsoft Academic Search

LDV measurements of the tangential and radial velocity components have been performed to investigate the flow patterns inside\\u000a a 4-valve single cylinder diesel engine for various engine speeds, swirl numbers and piston-bowl geometries, under conditions\\u000a similar to those of a production engine. The work focused on the near-wall region of the axisymmetric combustion chambers\\u000a where the strong swirl-squish and spray-wall

F. Payri; J. M. Desantes; J. V. Pastor

1996-01-01

276

Analysis of Forward Combustion Underground Coal Gasification Models.  

National Technical Information Service (NTIS)

A survey has been made of forward combustion gasification models that are available in the public domain. The six models obtained for study have been mathematically analyzed to determine their conceptual completeness and computational complexity. The mode...

D. W. Fausett L. K. Fausett

1984-01-01

277

Mathematical modelling of particle mixing effect on the combustion of municipal solid wastes in a packed-bed furnace.  

PubMed

Packed bed combustion is still the most common way to burn municipal solid wastes. In this paper, a dispersion model for particle mixing, mainly caused by the movement of the grate in a moving-burning bed, has been proposed and transport equations for the continuity, momentum, species, and energy conservation are described. Particle-mixing coefficients obtained from model tests range from 2.0x10(-6) to 3.0x10(-5)m2/s. A numerical solution is sought to simulate the combustion behaviour of a full-scale 12-tonne-per-h waste incineration furnace at different levels of bed mixing. It is found that an increase in mixing causes a slight delay in the bed ignition but greatly enhances the combustion processes during the main combustion period in the bed. A medium-level mixing produces a combustion profile that is positioned more at the central part of the combustion chamber, and any leftover combustible gases (mainly CO) enter directly into the most intensive turbulence area created by the opposing secondary-air jets and thus are consumed quickly. Generally, the specific arrangement of the impinging secondary-air jets dumps most of the non-uniformity in temperature and CO into the gas flow coming from the bed-top, while medium-level mixing results in the lowest CO emission at the furnace exit and the highest combustion efficiency in the bed. PMID:17697769

Yang, Yao Bin; Swithenbank, Jim

2007-08-13

278

Combustion of n-butane and isobutane in an internal combustion engine: A comparison of experimental and modeling results  

SciTech Connect

n-Butane and isobutane are used in a test engine to examine the importance of molecular structure in determining knock tendency. The experimental results are interpreted using a detailed chemical kinetic model. Temporally resolved samples were withdrawn from the combustion chamber, providing measured histories of the concentrations of a wide variety of reactant, olefin, carbonyl, and other intermediate and product species. Calculations show that RO{sub 2} isomerization reactions are more important contributors to chain branching in n-butane oxidation than in isobutane oxidation. Chain branching in isobutane oxidation is dependent on H-atom abstraction reactions involving HO{sub 2} and CH{sub 3}O{sub 2} radicals that occur at higher temperatures than RO{sub 2} isomerization reactions. Therefore, an isobutane mixture must be raised to a higher temperature than a n-butane mixture to achieve the same overall rate of reaction. 23 refs., 4 figs.

Wilk, R.D. (Union Coll., Schenectady, NY (USA)); Pitz, W.J.; Westbrook, C.K. (Lawrence Livermore National Lab., CA (USA)); Addagarla, S.; Miller, D.L.; Cernansky, N.P. (Drexel Univ., Philadelphia, PA (USA)); Green, R.M. (Sandia National Labs., Livermore, CA (USA))

1989-12-13

279

Heterogeneous Continuum Model of Aluminum Particle Combustion in Explosions  

Microsoft Academic Search

A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an\\u000a explosion. It combines gasdynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated\\u000a by Nigmatulin. Interphase mass, momentum, and energy exchange are prescribed by the phenomenological model of Khasainov. It\\u000a incorporates a combustion model

A. L. Kuhl; J. B. Bell; V. E. Beckner

2010-01-01

280

Surrogate Model Development for Fuels for Advanced Combustion Engines  

Microsoft Academic Search

The fuels used in internal-combustion engines are complex mixtures of a multitude of different types of hydrocarbon species. Attempting numerical simulations of combustion of real fuels with all of the hydrocarbon species included is highly unrealistic. Thus, a surrogate model approach is generally adopted, which involves choosing a few representative hydrocarbon species whose overall behavior mimics the characteristics of the

Krishnasamy Anand; youngchul Ra; Rolf Reitz; Bruce G Bunting

2011-01-01

281

Determination of liquid-fuel prevaporization and premixing in gas-turbine combustion chambers  

Microsoft Academic Search

A semiempirical mathematical model of the evaporation and distribution of liquid fuel in the prevaporization-premixing zone of a stationary gas turbine is developed, and the predictions obtained are compared with published experimental data and with the results of photographic, suction-probe, two-focus-laser-velocimeter, and light-scattering measurements on water sprays from 65-deg hollow-cone nozzles in a wind tunnel operating at 64 m\\/s. Good

J. Mrugalla

1983-01-01

282

GT8C gas turbine features new low-emission combustion chamber  

SciTech Connect

Since its appearance on the market ten years ago, the GT8 gas turbine from ABB has undergone a number of refinements that have led to the introduction of the model [open quotes]C[close quotes] turbine. The new GT8C unit shows improvements in power output and efficiency, as well as reduced emissions resulting from adoption of a new silo combustor provided with 19 dual-fuel EV-burners of the second generation. The GT8C ISO rating is 52.6 MW with natural gas fuel, a 9.6% increase over the GT8 rating. Its efficiency of 34.2% is 8.6% over the previous model, while the turbine inlet temperature, according to ISO definition, has been maintained practically unchanged, only 15[degree]C more than the previous model. ABB has submitted the GT8 machine to a [open quotes]systematic upgrading program[close quotes] directed at improving the economy of the unit while complying with present day regulations governing NO[sub x], CO and UHC emissions. 5 figs.

Chellini, R.

1994-06-01

283

COMBUSTION MODELING OF GLYCIDYL AZIDE POLYMER WITH DETAILED KINETICS  

Microsoft Academic Search

The steady-state combustion of the monopropellant glycidyl azide polymer (GAP) has been modeled using a one-dimensional, three-phase numerical model. Combustion characteristics of four formulations of cured GAP with varying amounts of the curing agent hexamethylene diisocyanate (HMDI) have been modeled. A two-step global decomposition condensed-phase kinetic mechanism has been developed, based on experimental data. A detailed gas-phase kinetic mechanism, with

KARTHIK V. PUDUPPAKKAM; MERRILL W. BECKSTEAD

2005-01-01

284

Gasdynamic Model of Turbulent Combustion in TNT Explosions  

Microsoft Academic Search

A model is proposed to simulate turbulent combustion in confined TNT explosions. It is based on: (i) the multi-component gasdynamic conservation laws, (ii) a fast-chemistry model for TNT-air combustion, (iii) a thermodynamic model for frozen reactants and equilibrium products, (iv) a high-order Godunov scheme providing a non-diffusive solution of the governing equations, and (v) an ILES approach whereby adaptive mesh

A L Kuhl; J B Bell; V E Beckner

2010-01-01

285

Gasdynamic model of turbulent combustion in TNT explosions  

Microsoft Academic Search

A model is proposed to simulate turbulent combustion in confined TNT explosions. It is based on: (i) the multi-component gasdynamic conservation laws, (ii) a fast-chemistry model for TNT–air combustion, (iii) a thermodynamic model for frozen reactants and equilibrium products, (iv) a high-order Godunov scheme providing a non-diffusive solution of the governing equations, and (v) an ILES approach whereby adaptive mesh

A. L. Kuhl; J. B. Bell; V. E. Beckner; H. Reichenbach

2011-01-01

286

Theory and modeling in combustion chemistry.  

National Technical Information Service (NTIS)

This paper discusses four important problems in combustion chemistry. In each case, resolution of the problem focuses on a single elementary reaction. Theoretical analysis of this reaction is discussed in some depth, with emphasis on its unusual features....

J. A. Miller

1996-01-01

287

Analysis of forward combustion underground coal gasification models  

Microsoft Academic Search

A survey has been made of forward combustion gasification models that are available in the public domain. The six models obtained for study have been mathematically analyzed to determine their conceptual completeness and computational complexity. The models range in scope of generality from a simple constrained mass balance model to a two-dimensional unsteady-state model. The computer code for each model

L. K. Fausett; D. W. Fausett

1984-01-01

288

Reaction diffusion pulses: a combustion model  

Microsoft Academic Search

We focus on a reaction-diffusion approach proposed recently for experiments on combustion processes, where the heat released by combustion follows first-order reaction kinetics. This case allows us to perform an exhaustive analytical study. Specifically, we obtain the exact expressions for the speed of the thermal pulses, their maximum temperature and the condition of self-sustenance. Finally, we propose two generalizations of

Daniel Campos; Joaquim Fort

2004-01-01

289

Modeling microbial chemotaxis in a diffusion gradient chamber.  

PubMed

The diffusion gradient chamber (DGC) has proven to be a useful experimental tool for studying population-level microbial growth and chemotaxis. A mathematical model capable of reproducing the population-level patterns formed as a result of cellular growth and chemotaxis in the DGC has been developed. The model consists of coupled partial differential balance equations for cells, chemoattractants, and a nutrient, which are solved simultaneously by the alternating direction implicit method. Modeling simulation results were compared with population-level migration patterns of Escherichia coli growing on glycerol and responding to a gradient of the chemoattractant aspartate for two different initial conditions. To accurately reproduce the experimental results, a second chemoattractant equation was necessary. The second chemoattractant has been identified as oxygen by directly measuring oxygen gradients in the DGC. Important trends observed experimentally and reproduced by the model include the formation of a chemotactic wave, a reduction in the wave velocity as it encounters higher chemoattractant concentrations, and chemotaxis in response to two different chemoattractants simultaneously. The model was also used to study the relative magnitude of cell fluxes due to random motility and chemotaxis, and the suppression of chemotaxis due to receptor saturation. PMID:18636457

Widman, M T; Emerson, D; Chiu, C C; Worden, R M

1997-07-01

290

Premixed Combustion Models for Gas Turbine with Stratified Fueling Systems  

NASA Astrophysics Data System (ADS)

The most popular conventional combustion models are the “Eddy-Break-Up Model” by Spalding and “Eddy Dissipation Model” by Magnussen, both of which are accepted as applicable to premixed flames. However, these models have not simulated all the premixed combustion phenomena. In this paper we assess four combustion models; (1) “Eddy Dissipation Model”: “Magnussen Model” (2) premixed combustion model of the “Katsuki Model” which controls the reaction rate by the Damköhler number; (3) the “Kido Model”, which predicts turbulent burning velocity by laminar burning velocity and turbulent characteristics and (4) the “Modified Katsuki Model”, in which the fluctuations of concentrations and temperature are solved by the transport equation. In present work, the Kido model is newly presented as computational code based on the flame cell concept and the modified Katsuki model is also developed for application to multi-fuel systems. Our study showed that the “Modified Katsuki Model” could predict the premixed combustion phenomena sufficiently and could trace the changes of the frame front.

Mandai, Shigemi; Uda, Nobuki; Nishida, Hiroyuki

291

Combustion chamber liner  

Microsoft Academic Search

This patent describes a sleeve extending concentrically through the bore of a piston engine; the inner side surface of the sleeve being designed to slidably support a piston; the outer side surface of the sleeve having a step configuration defining a first annular shoulder facing away from the cylinder head. The bore has a step configuration defining a second annular

Heydrich

1989-01-01

292

A model for steady-state HNF combustion  

SciTech Connect

A simple model for the combustion of solid monopropellants is presented. The condensed phase is treated by high activation energy asymptotics. The gas phase is treated by two limit cases: high activation energy, and low activation energy. This results in simplification of the gas phase energy equation, making an (approximate) analytical solution possible. The results of the model are compared with experimental results of Hydrazinium Nitroformate (HNF) combustion.

Louwers, J.; Gadiot, G.M.H.J.L. [TNO Prins Maurits Lab., Rijswijk (Netherlands); Brewster, M.Q. [Univ. of Illinois, Urbana, IL (United States); Son, S.F. [Los Alamos National Lab., NM (United States)

1997-09-01

293

Combustion heater  

Microsoft Academic Search

A wood burning combustion heater comprises a combustion chamber for long logs arranged to burn down from one end to the other in cigar-like fashion, an after-burner tube arrayed above and essentially parallel to the elongated logs with the air and burned gasses following an S-shaped path through the combustion chamber and out through the exhaust tube, an after-burner within

Kalenian

1980-01-01

294

A digital simulation of the exhaust nitric oxide and soot formation histories in the combustion chambers of a swirl chamber diesel engine  

Microsoft Academic Search

This work presents a computer simulation of the exhaust nitric oxide and soot emission histories from a four stroke, naturally\\u000a aspirated, Diesel engine with a swirl prechamber (divided chamber). The simulation is based on a thermodynamic analysis, which\\u000a was validated successfully concerning the performance of the engine (load, fuel consumption, maximum pressures, etc). The\\u000a analysis includes the calculation of the

Dimitrios A. Kouremenos; Constantine D. Rakopoulos; Dimitrios Hountalas; Petros Kotsiopoulos

1990-01-01

295

Analysis of unsteady solid-propellant combustion models (review)  

Microsoft Academic Search

Recent studies of solid-propellant combustion models are briefly analyzed. The models are divided into purely one-dimensional\\u000a (classical and phenomenological models with various generalizations of the Zel’dovich approach) and non-one-dimensional. The\\u000a latter include models with local non-one-dimensionality, which is always accompanied by local unsteadiness. This all can be\\u000a eliminated by averaging. The main disadvantage of unsteady solid-propellant combustion models, which is

L. K. Gusachenko; V. E. Zarko

2008-01-01

296

Laser Diagnostic Study of the Mechanism of a Periodic Combustion Instability in a Gas Turbine Model Combustor  

Microsoft Academic Search

To investigate the mechanisms leading to sustained thermoacoustic oscillations in swirl flames, a gas turbine model combustor was equipped with an optically accessible combustion chamber allowing the application of various laser techniques. The flame investigated was a swirled CH4\\/air diffusion flame (thermal power 10 kW, global equivalence ratio ? = 0.75) at atmospheric pressure which exhibited self-excited thermoacoustic oscillations at

P. Weigand; W. Meier; X. R. Duan; R. Giezendanner-Thoben; U. Meier

2005-01-01

297

A combustion model for IC engine combustion simulations with multi-component fuels  

Microsoft Academic Search

Reduced chemical kinetic mechanisms for the oxidation of representative surrogate components of a typical multi-component automotive fuel have been developed and applied to model internal combustion engines. Starting from an existing reduced mechanism for primary reference fuel (PRF) oxidation, further improvement was made by including additional reactions and by optimizing reaction rate constants of selected reactions. Using a similar approach

Youngchul Ra; Rolf D. Reitz

2011-01-01

298

Results of a model for premixed combustion oscillation  

SciTech Connect

Combustion oscillations are receiving renewed research interest due to the increasing application of lean premix (LPM) combustion to gas turbines. A simple, nonlinear model for premixed combustion is described in this paper. The model was developed to help explain specific experimental observations, and to provide guidance for the development of active control schemes based on nonlinear concepts. The model can be used to quickly examine instability trends associated with changes in equivalence ratio, mass flow rate, geometry, ambient conditions, and other pertinent factors. The model represents the relevant processes occurring in a fuel nozzle and combustor which are analogous to current LPM turbine combustors. Conservation equations for the fuel nozzle and combustor are developed from simple control volume analysis, providing a set of ordinary differential equations that can be solved on a personal computer. Combustion is modeled as a stirred reactor, with a bi- molecular reaction rate between fuel and air. A variety of numerical results and comparisons to experimental data are presented to demonstrate the utility of the model. Model results are used to understand the fundamental mechanisms which drive combustion oscillations, the effects of inlet air temperature and nozzle geometry on instability, and the effectiveness of active control schemes. The technique used in the model may also be valuable to understand oscillations in low NO{sub x} industrial burners.

Janus, M.C.; Richards, G.A.

1996-12-31

299

Pressure-gain combustion. Part 1: Model development  

SciTech Connect

A model for aerodynamically valved pulse combustion is presented. Particular emphasis is placed on using the model equations to identify characteristic length and time scales relevant to the design of pressure-gain combustors for gas turbine applications. The model is a control volume description of conservation laws for several regions of the pulse combustor. Combustion is modeled as a bimolecular reaction. Mixing between the fresh charge and the combustion products is modeled using a turbulent eddy time estimated from the combustor geometry and flow conditions. The model equations identify two characteristic lengths, which should be held constant during combustor scaleup, as well as certain exceptions to this approach. The effect of ambient operating pressure and inlet air temperature is also discussed.

Narayanaswami, L. [Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States); Richards, G.A. [Dept. of Energy, Morgantown, WV (United States). Morgantown Energy Technology Center

1996-07-01

300

Statistical model for combustion of high-metal magnesium-based hydro-reactive fuel  

NASA Astrophysics Data System (ADS)

We investigate experimentally and analytically the combustion behavior of a high-metal magnesium-based hydro-reactive fuel under high temperature gaseous atmosphere. The fuel studied in this paper contains 73% magnesium powders. An experimental system is designed and experiments are carried out in both argon and water vapor atmospheres. It is found that the burning surface temperature of the fuel is higher in water vapor than that in argon and both of them are higher than the melting point of magnesium, which indicates the molten state of magnesium particles in the burning surface of the fuel. Based on physical considerations and experimental results, a mathematical one-dimensional model is formulated to describe the combustion behavior of the high-metal magnesium-based hydro-reactive fuel. The model enables the evaluation of the burning surface temperature, the burning rate and the flame standoff distance each as a function of chamber pressure and water vapor concentration. The results predicted by the model show that the burning rate and the surface temperature increase when the chamber pressure and the water vapor concentration increase, which are in agreement with the observed experimental trends.

Hu, Jian-Xin; Han, Chao; Xia, Zhi-Xun; Huang, Li-Ya; Huang, Xu

2012-12-01

301

Combustion instabilities in the transition region of an unstable model rocket combustor  

Microsoft Academic Search

Gaseous methane and 90% hydrogen peroxide at an equivalence ratio of 0.8 were used to study combustion instabilities in the region where the system transitioned from stable to unstable combustion. A variable geometry unstable rocket combustor was used at a chamber pressure of 210 psi. The combustor consists of a coaxial shear injector and a simple dump plane combustor. The

Stanford C Rosen

2011-01-01

302

Pulsating Combustion Device Miniaturization.  

National Technical Information Service (NTIS)

The phenomenon of pulsating combustion remains one of the least understood forms of combustion. In this thesis, combustion oscillations are classified into the categories of chamber oscillations, system oscillations, and intrinsic oscillations. Two pulsat...

R. K. Crowe

1976-01-01

303

Liquid fuel combustion apparatus  

Microsoft Academic Search

A liquid fuel combustion apparatus is described comprising: wall means defining a cylindrical combustion chamber; a cylindrical portion of the wall means having a first port therein for receiving an ignition device and a first nipple integral with the wall means and surrounding the first port; means for introducing fuel and combustion air into the combustion chamber and for removing

K. Sawada; K. Kikuchi

1987-01-01

304

Chemiluminescent Emission Data For Kinetic Modeling Of Ethanol Combustion  

Microsoft Academic Search

Kinetic modeling is a powerful tool for combustion investigations and has been widely used. The validation of the model is a very important element of the work, to achieve realistic results, and it normally uses concentration profiles of some participant species. In this work, a kinetic model was validated using the chemiluminescent emissions of excited radicals produced in ethanol vapor

Leandro H. Benvenutti; Carla S. T. Marques; Celso A. Bertran

2004-01-01

305

Modelling of combustion process in the gas test engine  

Microsoft Academic Search

Paper presents results of modelling gas engine thermal cycle using AVL FIRE and KIVA 3V software. There are described three combustion models used in above mentioned software. Comparison of modelling results of thermal cycle of IC engine is presented in the paper.

Arkadiusz Jamrozik; Wojciech Tutak

2010-01-01

306

Modeling of an internal combustion engine for control analysis  

Microsoft Academic Search

Recent activity in nonthermodynamic modeling of automotive internal combustion engines with spark ignition, which are inherently nonlinear, is reviewed. A fundamental nonlinear model of the engine is presented, and a linear control-oriented model is derived from the nonlinear process. Techniques for experimental verification are examined, and a practical linear engine example incorporating multirate sampling is illustrated

Jeffrey A. Cook; Barry K. Powell

1988-01-01

307

Transient and translating gas jet modeling for pressure gain combustion applications  

Microsoft Academic Search

Major mechanisms governing the mixing process of a gas injected into a long confined chamber is analyzed when there's a relative motion between the two. Such applications arise in a wave rotor combustor (WRCVC) where the moving combustion chambers receive gas from stationary injectors for fueling and ignition. Counter rotating vortices govern the mixing process in such problems, which moves

Sameera Devsritha Wijeyakulasuriya

2011-01-01

308

Computing combustion noise by combining large eddy simulations with analytical models for the propagation of waves through turbine blades  

NASA Astrophysics Data System (ADS)

Two mechanisms control combustion noise generation as shown by Marble and Candel (1977) [1]: direct noise, in which acoustic waves propagate through the turbine stages and indirect noise, in which vorticity and/or entropy waves generate noise as they are convected through turbine stages. A method to calculate combustion-generated noise has been implemented in a tool called CHORUS. The method uses the large eddy simulations of the combustion chamber obtained with the unstructured solver AVBP developed at CERFACS (Schønfeld and Rudgyard, 1999 [2]) and analytical models for the propagation through turbine stages. The propagation models (Cumpsty and Marble, 1977 [3]) use the compact row hypothesis to write matching conditions between the inlet and the outlet of a turbine stage. Using numerical simulations, the validity of the analytical methods is studied and the errors made quantified.

Duran, Ignacio; Leyko, Matthieu; Moreau, Stéphane; Nicoud, Franck; Poinsot, Thierry

2013-01-01

309

An Experimental and Kinetic Modeling Study of Methyl Decanoate Combustion  

SciTech Connect

Biodiesel is typically a mixture of long chain fatty acid methyl esters for use in compression ignition engines. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This research study presents new combustion data for methyl decanoate in an opposed-flow diffusion flame. An improved detailed chemical kinetic model for methyl decanoate combustion is developed, which serves as the basis for deriving a skeletal mechanism via the direct relation graph method. The novel skeletal mechanism consists of 648 species and 2998 reactions. This mechanism well predicts the methyl decanoate opposed-flow diffusion flame data. The results from the flame simulations indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene.

Sarathy, S M; Thomson, M J; Pitz, W J; Lu, T

2010-02-19

310

Modeling low Reynolds number microgravity combustion problems  

NASA Astrophysics Data System (ADS)

The limit of low Reynolds number and low gravity allows a novel approximation to be developed for the equations of combustion theory. When the velocity field is separated into solenoidal and irrotational parts it is possible to show that the former is negligible to the lowest order in Reynolds number. Hence, the computation of the velocity field from the Navier Stokes equations may be replaced by the simpler task of solving Poissons equation for the irrotational field. This irrotational field is then substituted into the convective terms in energy and species equations, enabling solutions to be found for scalar quantities like the temperature and species mass fractions. The procedure is illustrated by examining two problems; the flow of air past a sphere blowing a light gas like helium, and combustion of volatiles blown from a porous sphere in an oxidizing crossfiow.

Baum, Howard R.

311

Theory and modeling in combustion chemistry  

SciTech Connect

This paper discusses four important problems in combustion chemistry. In each case, resolution of the problem focuses on a single elementary reaction. Theoretical analysis of this reaction is discussed in some depth, with emphasis on its unusual features. The four combustion problems and their elementary reactions are: (1) Burning velocities, extinction limits, and flammability limits: H+O{sub 2}{leftrightarrow}OH+O, (2) Prompt NO: CH+N{sub 2}{leftrightarrow}HCN+N, (3) the Thermal De-NO{sub x} Process: NH{sub 2}+NO{leftrightarrow}products, and (4) ``Ring`` formation in flames of aliphatic fuels and the importance of resonantly stabilized free radicals: C{sub 3}H{sub 3}{leftrightarrow}products.

Miller, J.A.

1996-10-01

312

Multidimensional Modelling of Diesel Combustion: Applications  

Microsoft Academic Search

\\u000a Various successful applications have proven the reliability of using multi-dimensional CFD tools to assist in diesel engine\\u000a research, design and development. Those applications can be categorized as follows: using CFD tools to reveal details about\\u000a invisible (or technically difficult and\\/or costly) in-cylinder processes of diesel combustion, so that guidance can be provided\\u000a to improve engine designs in terms of emissions

Yu Shi; Rolf D. Reitz

313

Phenomenology of Diesel Combustion and Modelling  

Microsoft Academic Search

\\u000a Diesel is the most efficient combustion engine today and it plays an important role in transport of goods and passengers on\\u000a road and on high seas. It is expected that the diesel engine will be active for another 100 years as increasingly economical\\u000a sources are found with the increase in oil prices offering incentive to the explorers. The emissions must

P. A. Lakshminarayanan; Yogesh V. Aghav

314

Modeling the effects of auxiliary gas injection and fuel injection rate shape on diesel engine combustion and emissions  

NASA Astrophysics Data System (ADS)

The effect of auxiliary gas injection and fuel injection rate-shaping on diesel engine combustion and emissions was studied using KIVA a multidimensional computational fluid dynamics code. Auxiliary gas injection (AGI) is the injection of a gas, in addition to the fuel injection, directly into the combustion chamber of a diesel engine. The objective of AGI is to influence the diesel combustion via mixing to reduce emissions of pollutants (soot and NO x). In this study, the accuracy of modeling high speed gas jets on very coarse computational grids was addressed. KIVA was found to inaccurately resolve the jet flows near walls. The cause of this inaccuracy was traced to the RNG k - ? turbulence model with the law-of-the-wall boundary condition used by KIVA. By prescribing the lengthscale near the nozzle exit, excellent agreement between computed and theoretical jet penetration was attained for a transient gas jet into a quiescent chamber at various operating conditions. The effect of AGI on diesel engine combustion and emissions was studied by incorporating the coarse grid gas jet model into a detailed multidimensional simulation of a Caterpillar 3401 heavy-duty diesel engine. The effects of AGI timing, composition, amount, orientation, and location were investigated. The effects of AGI and split fuel injection were also investigated. AGI was found to be effective at reducing soot emissions by increasing mixing within the combustion chamber. AGI of inert gas was found to be effective at reducing emissions of NOx by depressing the peak combustion temperatures. Finally, comparison of AGI simulations with experiments were conducted for a TACOM-LABECO engine. The results showed that AGI improved soot oxidation throughout the engine cycle. Simulation of fuel injection rate-shaping investigated the effects of three injection velocity profiles typical of unit-injector type, high-pressure common-rail type, and accumulator-type fuel injectors in the Caterpillar 3401 heavy-duty diesel engine. Pollutant emissions for the engine operating with different injection velocity profiles reflected the sensitivity of diesel engines to the location of pollutants within the combustion chamber, as influenced by the fuel injection.

Mather, Daniel Kelly

1998-11-01

315

Combustor nozzle for a fuel-flexible combustion system  

SciTech Connect

A combustor nozzle is provided. The combustor nozzle includes a first fuel system configured to introduce a syngas fuel into a combustion chamber to enable lean premixed combustion within the combustion chamber and a second fuel system configured to introduce the syngas fuel, or a hydrocarbon fuel, or diluents, or combinations thereof into the combustion chamber to enable diffusion combustion within the combustion chamber.

Haynes, Joel Meier (Niskayuna, NY); Mosbacher, David Matthew (Cohoes, NY); Janssen, Jonathan Sebastian (Troy, NY); Iyer, Venkatraman Ananthakrishnan (Mason, OH)

2011-03-22

316

Evaluation of low-temperature diesel combustion regimes with n-Heptane fuel in a constant-volume chamber  

Microsoft Academic Search

The concept of Low Temperature Combustion (LTC) has been advancing rapidly because it may reduce emissions of NOx and soot\\u000a simultaneously. Various LTC regimes that yield specific emissions have been investigated by a great number of experiments.\\u000a To accelerate the evaluation of the spray combustion characteristics of LTC, to identify the soot formation threshold in LTC,\\u000a and to implement the

U. B. Azimov; K. S. Kim; D. S. Jeong; Y. G. Lee

2009-01-01

317

Neural Transplantation Model Using Integration Co-culture Chamber  

NASA Astrophysics Data System (ADS)

Regenerative medicine is a promising therapy for injuries and diseases of the central nervous system (CNS). Implantation of stem cell-derived neurons into the recipient tissue is one of the key processes of the therapy. How the implanted cells establish functional connections with the intact neurons, and whether the established connections are maintained stably for a long time, remain unknown. Here, we report a novel co-culture device for visualizing interconnections between primary and differentiated neuronal cultures, and long-term monitoring of neuronal activity. A circular micro-chamber surrounded by another chamber is aligned on a microelectrode array (MEA). These chambers are interconnected through 36 micro-tunnels. Stem cell-derived neurons were cultured in the inner circular chamber, and primary neurons taken from mouse cortices were cultured in the surrounding chamber. Neurites outgrew into the micro-tunnels from both primary and differentiated neurons. The immunofluorescence images indicate that synaptic connections are formed between them. Propagation of electrical activity was observed 6 days after starting co-culture. More than half of the spontaneous activity was initiated from primary neurons, and probability of activity propagation to the stem cell-derived neurons gradually increased with culture days. These results suggest that our device is feasible for long-term monitoring of interaction between stem cell-derived cells and the recipient tissue.

Shimba, Kenta; Saito, Atsushi; Takeuchi, Akimasa; Takayama, Yuzo; Kotani, Kiyoshi; Jimbo, Yasuhiko

318

Geometric and number effect on damping capacity of Helmholtz resonators in a model chamber  

NASA Astrophysics Data System (ADS)

An acoustic cavity was selected as a stabilization device to control high-frequency combustion instabilities in gas turbines or liquid rocket engine combustors, and the acoustic damping capacity of the acoustic cavity was investigated for various geometric configurations under atmospheric non-reacting conditions. The tuning frequency of the acoustic cavity and the acoustic responses of a model chamber with a single acoustic cavity were studied first. Damping capacity was initially quantified through the frequency width of two split modes and the amplitude-damped ratio. The results showed that the cavity with the largest orifice area or the shortest orifice length was the most effective in acoustic damping of the harmful resonant mode. The effect of the number of cavities on acoustic damping capacity was also studied. Damping capacity was improved by increasing the number of cavities. For a better evaluation of acoustic damping capacity, two quantified parameters; the acoustic absorption, meaning the damping efficiency, and acoustic conductance, meaning the acoustic power loss, were introduced. The case was observed that has had insufficient loss of acoustic power in spite of having the highest absorption efficiency. As a result, fine geometric tuning for the acoustic cavity is required for the sufficient passive control. Also, the choice of the number of cavities is important to optimize the damping efficiency and absolute damping loss in consideration of the restriction of the cavity volume.

Kim, H. J.; Cha, J.-P.; Song, J.-K.; Ko, Y. S.

2010-08-01

319

Kinetic models of combustion of kerosene and its components  

Microsoft Academic Search

Modern investigations on creation of kinetic models of combustion of hydrocarbons entering into the composition of kerosene\\u000a and kerosene as a whole have been analyzed. Certain recommendations on application of these models to calculation of actual\\u000a gasdynamic flows have been given.

G. Ya. Gerasimov; S. A. Losev

2005-01-01

320

An EDC-based turbulent premixed combustion model  

Microsoft Academic Search

In the present study, a new turbulent premixed combustion model is proposed by integrating the Coherent Flame Model with the modified eddy dissipation concept, and relating the fine structure mass fraction to the flame surface density. First, experimental results of turbulent flame speed available from literature are compared with the predicted results at different turbulence intensities to validate the flame

Muhsin M. Ameen; R. V. Ravikrishna

2011-01-01

321

Combustion  

NSDL National Science Digital Library

In this chemistry activity, learners discover that the weight of the product of combustion is greater than that of the starting material. Learners will compare the weight of steel wool before and after it is heated. Learners are asked to consider why the steel wool weighs more (oxidation) as well as write the balanced chemical equation for the burning of steel. This activity uses an open flame; adult supervision is recommended. The resource includes notes for educators and extension ideas.

House, The S.

2013-05-15

322

Comparison of numerical methods and combustion models for LES of a ramjet  

NASA Astrophysics Data System (ADS)

Ramjets are very sensitive to instabilities and their numerical predictions can only be addressed adequately by Large Eddy Simulation (LES). With this technique, solvers can be implicit or explicit and handle structured, unstructured or hybrid meshes, etc. Turbulence and combustion models are other sources of differences. The impact of these options is here investigated for the ONERA ramjet burner. To do so, two LES codes developed by ONERA and CERFACS compute one stable operating condition. Preliminary LES results of the two codes underline the overall robustness of LES. Mean flow features at the various critical sections are reasonably well predicted by both codes. Disagreement mainly appear in the chamber where combustion positions differ pointing to the importance of the combustion and subgrid mixing models. The two LES produce different energy containing motions. With CEDRE, a low frequency dominates while AVBP produces different ranges of low frequencies that can be linked with acoustic modes of the configuration. To cite this article: A. Roux et al., C. R. Mecanique 337 (2009).

Roux, A.; Reichstadt, S.; Bertier, N.; Gicquel, L.; Vuillot, F.; Poinsot, T.

2009-06-01

323

An experimental and kinetic modeling study of the combustion of n-butane and isobutane in an internal combustion engine  

SciTech Connect

Butane is the simplest alkane fuel for which more than a single structural isomer is possible. In the present study, n-butane and isobutane are used in a test engine to examine the importance of molecular structure in determining knock tendency, and the experimental results are interpreted using a detailed chemical kinetic model. A sampling valve was used to extract reacting gases from the combustion chamber of the engine operated in a skip-fire mode. Samples were withdrawn at different times during the skip cycles, providing a measure of the concentrations of a wide variety of reactant, olefin, carbonyl, and other intermediate and product species. The chemical kinetic model predicted the formation of all the intermediate species measured in the experiments. The agreement between the measured and predicted values is mixed and is discussed. Calculations show that RO{sub 2} isomerization reactions are more important contributors to chain branching in n-butane oxidation is dependent on H-atom abstraction reactions involving HO{sub 2} and CH{sub 3}O{sub 2} radicals that occur at higher temperatures than RO{sub 2} isomerization reactions. Therefore, an isobutane mixture must be raised to a higher temperature than a n-butane mixture to achieve the same overall rate of reaction. 48 refs., 3 figs., 2 tabs.

Wilk, R.D.; Addagarla, S.; Miller, D.L.; Cernansky, N.P.; Pitz, W.J.; Westbrook, C.K.; Green, R.M. (Union Coll., Schenectady, NY (USA); Drexel Univ., Philadelphia, PA (USA); Lawrence Livermore National Lab., CA (USA); Sandia National Labs., Livermore, CA (USA))

1989-10-13

324

Numerical modeling of hydrogen-fueled internal combustion engines  

SciTech Connect

Major progress was achieved in the last year in advancing the modeling capabilities of hydrogen-fueled engines, both in support of the multi-laboratory project with SNL and LLNL to develop a high-efficiency, low emission powerplant and to provide the engine design tools to industry and research laboratories for hydrogen-fueled engines and stationary power generators. The culmination of efforts on many fronts was the excellent comparison of the experimental data from the Onan engine, operated by SNL.These efforts include the following. An extensive study of the intake flow culminated in a major understanding of the interdependence of the details of the intake port design and the engine operating condition on the emissions and efficiency. This study also resulted in design suggestions for future engines and general scaling laws for turbulence that enables the KIVA results to be applied to a wide variety of operating conditions. The research on the turbulent combustion of hydrogen brought into perspective the effect of the unique aspects of hydrogen combustion and their influence on possible models of turbulent combustion. The effort culminated in a proposed model for turbulent hydrogen combustion that is in agreement with available literature. Future work will continue the development in order to provide a generally predictive model for hydrogen combustion. The application of the combustion model to the Onan experiments elucidated the observed improvement of the efficiency of the engine with the addition of a shroud on the intake valve. This understanding will give guidance to future engine design for optimal efficiency. Finally, a brief summary is given of the extensions and refinements of the KIVA-3 code, in support of future designers of hydrogen-fueled engines.

Johnson, N.L.; Amsden, A.A.; Butler, T.D. [Los Alamos National Lab., NM (United States). Theoretical Div.

1996-07-01

325

Modeling Chamber Transport for Heavy-Ion Fusion  

SciTech Connect

In a typical thick-liquid-wall scenario for heavy-ion fusion (HIF), between 70 and 200 high-current beams approach the target chamber in entry pipes and propagate {approx}3 m to the target. Since molten-salt jets are planned to protect the chamber wall, the beams move through vapor from the jets, and collisions between beam ions and this background gas both strip the ions and ionize the gas molecules. Radiation from the preheated target causes further beam stripping and gas ionization. Because of this stripping, beams for HIF are expected to require substantial neutralization in a target chamber. Much recent research has, therefore, focused on beam neutralization by electron sources that were neglected in earlier simulations, including emission from walls and the target, photoionization by the target radiation, and preneutralization by a plasma generated along the beam path. When these effects are included in simulations with practicable beam and chamber parameters, the resulting focal spot is approximately the size required by a distributed radiator target.

Sharp, William M. [Lawrence Livermore National Laboratory (United States); Callahan, Debra A. [Lawrence Livermore National Laboratory (United States); Tabak, Max [Lawrence Livermore National Laboratory (United States); Laboratory, Simon S. Yu Lawrence Berkeley National; Peterson, Per F. [University of California Berkeley (United States); Welch, Dale R. [Mission Research Corporation (United States); Rose, David V. [Mission Research Corporation (United States); Olson, Craig L. [Sandia National Laboratory (United States)

2003-05-15

326

Modelling ionization chamber response to nonstandard beam configurations  

Microsoft Academic Search

Novel technologies aiming at improving target dose coverage while minimising dose to organs at risk use delivery of radiation fields that significantly deviate from reference conditions defined in protocols such as TG-51 and TRS-398. The use of ionization chambers for patient-specific quality assurance of these new delivery procedures calibrated in reference conditions increases the uncertainties on dose delivery. The conversion

L. Tantot; J. Seuntjens

2008-01-01

327

OUTDOOR SMOG CHAMBER EXPERIMENTS TO TEST PHOTOCHEMICAL MODELS: PHASE 2  

EPA Science Inventory

The smog chamber facility of the University of North Carolina was used to provide experimental data for developing and testing kinetic mechanisms of photochemical smog formation. In this study, 128 pairs of experiments were performed using NOx and various hydrocarbons and hydroca...

328

Total scattering cross section improvements from electromagnetic reverberation chambers modeling and stochastic formalism  

Microsoft Academic Search

This article is dedicated to deterministic and stochastic improvements for TSCS computations. Firstly, the To- tal Scattering Cross Section (TSCS) measurements are achieved in a numerical Reverberation Chamber (RC) for different targets. From a theoretical point of view, a free-space environment (for instance an anechoic chamber modeled numerically by absorbing boundary conditions) jointly with plane waves stimulations are needed to

Sebastien Lallechere; Ibrahim El Baba; Pierre Bonnet; Francoise Paladian

2011-01-01

329

COMPENSATING FOR WALL EFFECTS IN IAQ (INDOOR AIR QUALITY) CHAMBER TESTS BY MATHEMATICAL MODELING  

EPA Science Inventory

The paper presents mechanistic mathematical models that account for two phenomena: interior surfaces of a state-of-the-art emissions test chamber acting as a transient sink for organic emissions; the effect of increasing chamber concentration on the emission rate of the source. A...

330

STRUCTURE-BASED PREDICTIVE MODEL FOR COAL CHAR COMBUSTION  

SciTech Connect

Progress was made this period on a number of tasks. A significant advance was made in the incorporation of macrostructural ideas into high temperature combustion models. Work at OSU by R. Essenhigh in collaboration with the University of Stuttgart has led to a theory that the zone I / II transition in char combustion lies within the range of conditions of interest for pulverized char combustion. The group has presented evidence that some combustion data, previously interpreted with zone II models, in fact takes place in the transition from zone II to zone 1. This idea was used at Brown to make modifications to the CBK model (a char kinetics package specially designed for carbon burnout prediction, currently used by a number of research and furnace modeling groups in academia and industry). The resulting new model version, CBK8, shows improved ability to predict extinction behavior in the late stages of combustion, especially for particles with low ash content. The full development and release of CBK8, along with detailed descriptions of the role of the zone 1/2 transition will be reported on in subsequent reports. ABB-CE is currently implementing CBK7 into a special version of the CFD code Fluent for use in the modeling and design of their boilers. They have been appraised of the development, and have expressed interest in incorporating the new feature, realizing full CBK8 capabilities into their combustion codes. The computational chemistry task at OSU continued to study oxidative pathways for PAH, with emphasis this period on heteroatom containing ring compounds. Preliminary XPS studies were also carried out. Combustion experiments were also carried out at OSU this period, leading to the acquisition of samples at various residence times and the measurement of their oxidation reactivity by nonisothermal TGA techniques. Several members of the project team attended the Carbon Conference this period and made contacts with representatives from the new FETC Consortium for Premium Carbon Products from Coal. Possibilities for interactions with this new center will be explored. Also this period, an invited review paper was prepared for the 27th International Symposium on Combustion, to be held in Boulder, Colorado in August. The paper is entitled; "Structure, Properties, and Reactivity of Solid Fuels," and reports on a number of advances made in this collaborative project.

CHRISTOPHER M. HADAD; JOSEPH M. CALO; ROBERT H. ESSENHIGH; ROBERT H. HURT

1998-09-11

331

Liquid fuel combustion apparatus  

Microsoft Academic Search

This patent describes a vaporized liquid fuel combustion apparatus of the type including: a cylinder defining a combustion chamber, the cylinder having an inlet end for receipt of combustion air and an outlet end for exhausting gaseous combustion products; an end plate covering the inlet end of the cylinder; a blower, including a rotor and a casing, for supplying combustion

K. Sawada; Y. Kimijima; H. Umehara

1986-01-01

332

Combustion modeling of RDX, HMX and GAP with detailed kinetics  

NASA Astrophysics Data System (ADS)

A one-dimensional, steady-state numerical model of the combustion of homogeneous solid propellant has been developed. The combustion processes is modeled in three regions: solid, two-phase (liquid and gas) and gas. Conservation of energy and mass equations are solved in the two-phase and gas regions and the eigenvalue of the system (the mass burning rate) is converged by matching the heat flux at the interface of these two regions. The chemical reactions of the system are modeled using a global kinetic mechanism in the two-phase region and an elementary kinetic mechanism in the gas region. The model has been applied to RDX, HMX and GAP. There is very reasonable agreement between experimental data and model predictions for burning rate, temperature sensitivity, surface temperature, adiabatic flame temperature, species concentration profiles and melt-layer thickness. Many of the similarities and differences in the combustion of RDX and HMX are explained from sensitivity analysis results. The combustion characteristics of RDX and HMX are similar because of their similar chemistry. Differences in combustion characteristics arise due to differences in melting temperature, vapor pressure and initial decomposition steps. A reduced mechanism consisting of 18 species and 39 reactions was developed from the Melius-Yetter RDX mechanism (45 species, 232 reactions). This reduced mechanism reproduces most of the predictions of the full mechanism but is 7.5 times faster. Because of lack of concrete thermophysical property data for GAP, the modeling results are preliminary but indicate what type of experimental data is necessary before GAP can be modeled with more certainty.

Davidson, Jeffrey Edward

333

Fluidized bed combustion system and method having an integral recycle heat exchanger with a transverse outlet chamber  

Microsoft Academic Search

This paper describes a fluidized bed combustion system. It comprises: an enclosure; means defining a furnace section and a recycle heat exchange section in the enclosure; a fluidized bed formed in each of the sections; a separating section for receiving a mixture of flue gases and entrained particulate material from the fluidized bed in the furnace section and separating the

A. M. Hansen; W. D. Stevens; J. P. Winkin

1991-01-01

334

Laser induced fluorescence measurements of the thickness of fuel films on the combustion chamber surface of a gasoline SI engine  

Microsoft Academic Search

Up to 90% of the unburnt hydrocarbon emissions (UHCs) from modern 4-stroke gasoline engines occur during cold starting. Slow vapourisation particularly from films of fuel in the intake port, and on the manifold and cylinder walls leads regions of rich mixture and incomplete combustion. To reduce UHCs it is useful to know where, and how thick, these wall films are

M. C. Jerm; T. Nöel; W. G. Doherty

335

Modeling of combustion processes in a solid fuel particle  

Microsoft Academic Search

During the production of granules or uranium oxide, granules of ion-exchange resin, loaded with uranium ions, are burned to remove the resin matrix and leave a uranium oxide ''ash''. Under some conditions of combustion, the oxide granules are produced in a highly fractured, porous state, while other conditions result in hard, dense, solid granules. ABAQUS was used to model the

1989-01-01

336

Numerical problems in the solution of oxidation and combustion models  

Microsoft Academic Search

Faced with large and detailed kinetic schemes of pyrolysis, partial oxidation and combustion of hydrocarbon mixtures, the complex process models usually constitute stiff systems of both differential and coupled differential-algebraic equations. This paper discusses different typical applications of a new robust and efficient numerical integration method to solve these problems. The examples refer to gas solid catalytic reactors, partial oxidation

D. Manca; G. Buzzi-Ferraris; T. Faravelli; E. Ranzi

2001-01-01

337

A combustion kinetic model for estimating diesel engine NOx emissions  

Microsoft Academic Search

A phenomenological combustion model, which considers the space and time evolutions of a reacting diesel fuel jet, has been developed in order to estimate the instantaneous NOx concentration in a diesel engine cylinder from the start of the injection until the exhaust valve opening. The total injected fuel mass has been divided into different fuel packages, through the fuel injection

J. J. Hernandez; M. Lapuerta; J. Perez-Collado

2006-01-01

338

Numerical modeling of hydrogen-fueled internal combustion engines  

SciTech Connect

The planned use of hydrogen as the energy carrier of the future introduces new challenges and opportunities, especially to the engine design community. Hydrogen is a bio-friendly fuel that can be produced from renewable resources and has no carbon dioxide combustion products; and in a properly designed ICE, almost zero NO{sub x} and hydrocarbon emissions can be achieved. Because of the unique properties of hydrogen combustion - in particular the highly wrinkled nature of the laminar flame front due to the preferential diffusion instability - modeling approaches for hydrocarbon gaseous fuels are not generally applicable to hydrogen combustion. This paper reports on the current progress to develop a engine design capability based on KIVA family of codes for hydrogen-fueled, spark-ignited engines in support of the National Hydrogen Program. A turbulent combustion model, based on a modified eddy-turnover model in conjunction with an intake flow valve model, is found to describe well the efficiency and NO{sub x} emissions of this engine satisfy the Equivalent Zero Emission Vehicle (EZEV) standard established by the California Resource Board. 26 refs., 10 figs., 1 tab.

Johnson, N.L.; Amsden, A.A.

1996-12-31

339

Two-Phase Model of Combustion in Explosions.  

National Technical Information Service (NTIS)

A two-phase model for Aluminum particle combustion in explosions is proposed. It combines the gas-dynamic conservation laws for the gas phase with the continuum mechanics laws of multi-phase media, as formulated by Nigmatulin. Inter-phase mass, momentum a...

A. L. Kunl B. Khasainov J. Bell

2006-01-01

340

Controlling chaos in a model of thermal pulse combustion  

Microsoft Academic Search

We describe methods for automating the control and tracking of states within or near a chaotic attractor. The methods are applied in a simulation using a recently developed model of thermal pulse combustion as the dynamical system. The controlled state is automatically tracked while a parameter is slowly changed well beyond the usual flame-out point where the chaotic attractor ceases

M. A. Rhode; R. W. Rollinsa; A. J. Markworth; K. D. Edwards; K. Nguyen; C. S. Daw; J. F. Thomas

1995-01-01

341

A reduced order full plant model for oxyfuel combustion  

Microsoft Academic Search

The linkage of models generated in different commercial and\\/or proprietary software packages is becoming the state-of-the-art for the investigation of power generation applications. Here, a sophisticated process modelling software package, gPROMS, has been linked with a commercial CFD code, ANSYS FLUENT version 12, in order to create a reduced order model (ROM) for oxyfuel combustion. This is the first such

P. J. Edge; P. J. Heggs; M. Pourkashanian; P. L. Stephenson; A. Williams

342

Tissue Destruction Induced by Porphyromonas gingivalis Infection in a Mouse Chamber Model Is Associated with Host Tumor Necrosis Factor Generation  

PubMed Central

Intrachamber challenge with Porphyromonas gingivalis strain 381 in a mouse subcutaneous chamber model results in a local infection that progresses to exfoliation of the chambers within 15 days. This study was designed to elucidate the contribution of host reactions to tissue destruction manifested by chamber exfoliation in animals infected with P. gingivalis. Chamber fluids showed increasing levels of prostaglandin E2 with infection, and the levels of tumor necrosis factor (TNF) in chamber fluids peaked just before chamber exfoliation. Intraperitoneal injection of a TNF inhibitor, thalidomide (TH), reduced the number of exfoliated chambers, while indomethacin had no effect. Exogenous TNF in chambers without bacterial infection did not cause chamber exfoliation but induced neutrophil infiltration. In a dual-chamber model, two chambers were implanted in the same mouse. One chamber was infected with P. gingivalis, and 9 days later exogenous TNF was added to the other chamber. Altogether, 66.67% of uninfected chambers were exfoliated between day 11 and day 16, although no bacteria were recovered from uninfected chambers. TH treatment alleviated both infected and uninfected chamber exfoliation. In this study, tissue destruction caused by P. gingivalis 381 infection was due to the elevation of the TNF levels and not due to local bacterial activities. Our results further indicate that local infection by P. gingivalis 381, a nondisseminating strain, actually has systemic effects on the host pathological outcome.

Lin, Yuh-Yih; Huang, Jan-Hung; Lai, Yo-Yin; Huang, Han-Ching; Hu, Suh-Woan

2005-01-01

343

A regenerative multiple zone model for HCCI combustion  

SciTech Connect

A new conserved scalar approach, the so-called regenerative multiple zone (RMZ) model, is introduced to simulate combustion in homogeneous charge compression ignition (HCCI) engines with significant products of combustion. In this approach, two conserved scalars are introduced, the mixture fraction Z and the initial exhaust gas fraction J, to determine uniquely the state of the reactive system as a function of the two conserved scalars and time. For the numerical solution of the HCCI combustion, the conserved scalar plane is divided into different zones, which represent homogeneous reactors with constant initial exhaust gas level. Particularly, the zones are created based on the distribution of the initial exhaust gases and are mixed and regenerated at every time step during combustion in order to account for the history effects which are due to the finite rate chemistry. A proper methodology to create and initialize the new zones during the combustion, the so-called zone creation strategy (ZCS), is also proposed. For validation, the RMZ model is implemented in the 2DRD code, which is a computational fluid dynamics code that solves the governing equations for a two-dimensional reaction-diffusion problem. Initially, the consistency of the new model is validated in a one-dimensional reaction-diffusion (RD) case. Subsequently, the necessity for a proper zone creation strategy is demonstrated by a two-dimensional RD case. Next, a parametric study is performed to investigate the sensitivity of the new model on the maximum number of zones that is used. Finally, the limitations as well as the advantages of the RMZ model are discussed. (author)

Hamosfakidis, Vasileios; Im, Hong G.; Assanis, Dennis N. [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

2009-04-15

344

Hydrogen program combustion research: Three dimensional computational modeling  

SciTech Connect

We have significantly increased our computational modeling capability by the addition of a vertical valve model in KIVA-3, code used internationally for engine design. In this report the implementation and application of the valve model is described. The model is shown to reproduce the experimentally verified intake flow problem examined by Hessel. Furthermore, the sensitivity and performance of the model is examined for the geometry and conditions of the hydrogen-fueled Onan engine in development at Sandia National Laboratory. Overall the valve model is shown to have comparable accuracy as the general flow simulation capability in KIVA-3, which has been well validated by past comparisons to experiments. In the exploratory simulations of the Onan engine, the standard use of the single kinetic reaction for hydrogen oxidation was found to be inadequate for modeling the hydrogen combustion because of its inability to describe both the observed laminar flame speed and the absence of autoignition in the Onan engine. We propose a temporary solution that inhibits the autoignition without sacrificing the ability to model spark ignition. In the absence of experimental data on the Onan engine, a computational investigation was undertaken to evaluate the importance of modeling the intake flow on the combustion and NO{sub x} emissions. A simulation that began with the compression of a quiescent hydrogen-air mixture was compared to a simulation of the full induction process with resolved opening and closing of the intake valve. Although minor differences were observed in the cylinder-averaged pressure, temperature, bulk-flow kinetic energy and turbulent kinetic energy, large differences where observed in the hydrogen combustion rate and NO{sub x} emissions. The flow state at combustion is highly heterogeneous and sensitive to the details of the bulk and turbulent flow and that an accurate simulation of the Onan engine must include the modeling of the air-fuel induction.

Johnson, N.L.; Amsden, A.A.; Butler, T.D.

1995-05-01

345

Three-dimensional modeling of diesel engine intake flow, combustion and emissions-II  

SciTech Connect

A three-dimensional computer code, KIVA, is being modified to include state-of-the-art submodels for diesel engine flow and combustion. Improved and/or new submodels which have already been implemented and previously reported are: Wall heat transfer with unsteadiness and compressibility, laminar-turbulent characteristic time combustion with unburned HC and Zeldo`vich NO{sub x}, and spray/wall impingement with rebounding and sliding drops. Progress on the implementation of improved spray drop drag and drop breakup models, the formulation and testing of a multistep kinetics ignition model and preliminary soot modeling results are described in this report. In addition, the use of a block structured version of KIVA to model the intake flow process is described. A grid generation scheme has been developed for modeling realistic (complex) engine geometries, and computations have been made of intake flow in the ports and combustion chamber of a two-intake-valve engine. The research also involves the use of the code to assess the effects of subprocesses on diesel engine performance. The accuracy of the predictions is being tested by comparisons with engine experiments. To date, comparisons have been made with measured engine cylinder pressure, temperature and heat flux data, and the model results are in good agreement with the experiments. Work is in progress that will allow validation of in-cylinder flow and soot formation predictions. An engine test facility is described that is being used to provide the needed validation data. Test results have been obtained showing the effect of injection rate and split injections on engine performance and emissions.

Reitz, R.D.; Rutland, C.J.

1993-09-01

346

Fuel combustion system and method of operation for an Otto-cycle internal combustion engine  

SciTech Connect

This paper describes a method of combusting a predetermined combustible mixture of fuel and air in an Otto-cycle internal combustion engine including a main combustion chamber, first control valve means for admitting the combustible mixture into the main combustion chamber, an auxiliary combustion chamber, second control valve means for opening and blocking fluid communication between the main combustion chamber and the auxiliary combustion chamber. It comprises: admitting the combustible mixture into the main combustion chamber during an intake phase of the cycle; compressing and thereby pressurizing the combustible mixture in the main combustion chamber during a compression phase of the cycle; opening the second control valve means at a predetermined time during a latter portion of the compression phase in order to admit a portion of pressurized combustible mixture into the auxiliary combustion chamber; igniting the portion of combustible mixture admitted to the auxiliary combustion chamber and thereby forming expanding burning gases; directing the expanding burning gases from the auxiliary combustion chamber into the main combustion chamber in order to penetrate and cause ignition and burning of the remaining pressurized combustible mixture in the main combustion chamber; and closing the second control valve means at a predetermined time prior to about the beginning of the next compression phase.

Bailey, J.M.

1991-11-26

347

Development of low-pollutant pre-mixed burner for residential gas furnaces with cylindrical combustion chambers  

Microsoft Academic Search

Ruhrgas developed the Thermomax burner system (TBS) to reduce nitrogen oxide pollution by residential gas burners. The burners, designed for maximum heat inputs of approx. 50 kW, are premixed fuel-lean units developed for laminar combustion. The flame is retained by a temperature-resistant orifice plate. The burners developed for different gas appliances excel by their sample design, outstanding heat transfer properties

H. Berg; T. Jannemann

1988-01-01

348

Multiple Mapping Conditioning: A New Modelling Framework for Turbulent Combustion  

Microsoft Academic Search

\\u000a Multiple mapping conditioning (MMC) is a relatively new addition to the list of models for turbulent combustion that unifies\\u000a the features of the probability density function, conditional moment closure and mapping closure models. This chapter presents\\u000a the major concepts and theory of MMC without the detailed derivations which can be found in the cited literature. While the\\u000a fundamental basis remains

M. J. Cleary; A. Y. Klimenko

349

Chemical Kinetic Modeling of Combustion of Automotive Fuels  

SciTech Connect

The objectives of this report are to: (1) Develop detailed chemical kinetic reaction models for components of fuels, including olefins and cycloalkanes used in diesel, spark-ignition and HCCI engines; (2) Develop surrogate mixtures of hydrocarbon components to represent real fuels and lead to efficient reduced combustion models; and (3) Characterize the role of fuel composition on production of emissions from practical automotive engines.

Pitz, W J; Westbrook, C K; Silke, E J

2006-11-10

350

Chemical Looping Combustion System-Fuel Reactor Modeling  

SciTech Connect

Chemical looping combustion (CLC) is a process in which an oxygen carrier is used for fuel combustion instead of air or pure oxygen as shown in the figure below. The combustion is split into air and fuel reactors where the oxidation of the oxygen carrier and the reduction of the oxidized metal occur respectively. The CLC system provides a sequestration-ready CO2 stream with no additional energy required for separation. This major advantage places combustion looping at the leading edge of a possible shift in strict control of CO2 emissions from power plants. Research in this novel technology has been focused in three distinct areas: techno-economic evaluations, integration of the system into power plant concepts, and experimental development of oxygen carrier metals such as Fe, Ni, Mn, Cu, and Ca. Our recent thorough literature review shows that multiphase fluid dynamics modeling for CLC is not available in the open literature. Here, we have modified the MFIX code to model fluid dynamic in the fuel reactor. A computer generated movie of our simulation shows bubble behavior consistent with experimental observations.

Gamwo, I.K.; Jung, J. (ANL); Anderson, R.R.; Soong, Y.

2007-04-01

351

A model for double base propellant combustion  

Microsoft Academic Search

Several models have been developed to predict the burning rate of double base propellant as a function of pressure and initial temperature. The increasingly numerous experimental results (most from Kubota) provide a well established data base which allows one to verify the reliability of the numerical models. A complete model must determine the burning rate vs. pressure, initial temperature, and

Bizot

1987-01-01

352

Boiler using combustible fluid  

DOEpatents

A fluid fuel boiler is described comprising a combustion chamber, a cover on the combustion chamber having an opening for introducing a combustion-supporting gaseous fluid through said openings, means to impart rotation to the gaseous fluid about an axis of the combustion chamber, a burner for introducing a fluid fuel into the chamber mixed with the gaseous fluid for combustion thereof, the cover having a generally frustro-conical configuration diverging from the opening toward the interior of the chamber at an angle of between 15/sup 0/ and 55/sup 0/; means defining said combustion chamber having means defining a plurality of axial hot gas flow paths from a downstream portion of the combustion chamber to flow hot gases into an upstream portion of the combustion chamber, and means for diverting some of the hot gas flow along paths in a direction circumferentially of the combustion chamber, with the latter paths being immersed in the water flow path thereby to improve heat transfer and terminating in a gas outlet, the combustion chamber comprising at least one modular element, joined axially to the frustro-conical cover and coaxial therewith. The modular element comprises an inner ring and means of defining the circumferential, radial, and spiral flow paths of the hot gases.

Baumgartner, H.; Meier, J.G.

1974-07-03

353

Finite element model for turbulent spray combustion  

NASA Astrophysics Data System (ADS)

A finite element model for the prediction of spray flame field is presented. An Eulerian-Lagrangian approach is employed to model the reacting flow field of a spray combustor. The unsteady axisymmetric gas-phase equations are presented in Eulerian coordinates and the liquid-phase equations are formulated in Lagrangian coordinates. Turbulence is represented by the k-sigma model, and the reaction rate is determined by the modified eddy break-up model. Numerical results for the droplet trajectories and the effects of the evaporation models are discussed.

Kim, Y. M.; Chung, T. J.; Chang, K. S.

1990-01-01

354

Application of explicit convolution to numerical modeling of turbulent combustion  

NASA Astrophysics Data System (ADS)

Combustion devices mostly rely on turbulent combustion to produce energy in an efficient way. Today computational power has enabled numerical modeling of these real configurations using Large Eddy Simulations(LES). However the scales at which chemical reactions occur are even smaller than the smallest flow scales and require a model. In this work we propose to use spatially filtered 1D laminar flamelet, for simulating a turbulent flame, on a grid coarser than adequate for resolution of chemical scales. A numerical simulation which resolves all the flow and chemical scales is computed as a benchmark and a priori analysis is carried out to test the hypothesis. To test the validity of the model a posteriori analysis using a laminar flame convoluted with top hat is carried out.

Mukhopadhyay, S.; Bastiaans, R. J. M.; van Oijen, J. A.; de Goey, L. P. H.

2013-10-01

355

A filtered tabulated chemistry model for LES of premixed combustion  

SciTech Connect

A new modeling strategy called F-TACLES (Filtered Tabulated Chemistry for Large Eddy Simulation) is developed to introduce tabulated chemistry methods in Large Eddy Simulation (LES) of turbulent premixed combustion. The objective is to recover the correct laminar flame propagation speed of the filtered flame front when subgrid scale turbulence vanishes as LES should tend toward Direct Numerical Simulation (DNS). The filtered flame structure is mapped using 1-D filtered laminar premixed flames. Closure of the filtered progress variable and the energy balance equations are carefully addressed in a fully compressible formulation. The methodology is first applied to 1-D filtered laminar flames, showing the ability of the model to recover the laminar flame speed and the correct chemical structure when the flame wrinkling is completely resolved. The model is then extended to turbulent combustion regimes by including subgrid scale wrinkling effects in the flame front propagation. Finally, preliminary tests of LES in a 3-D turbulent premixed flame are performed. (author)

Fiorina, B.; Auzillon, P.; Darabiha, N.; Gicquel, O.; Veynante, D. [EM2C - CNRS, Ecole Centrale Paris, 92295 Chatenay Malabry (France); Vicquelin, R. [EM2C - CNRS, Ecole Centrale Paris, 92295 Chatenay Malabry (France); GDF SUEZ, Pole CHENE, Centre de Recherche et d'Innovation Gaz et Energies Nouvelles, 93211 Saint-Denis la Plaine (France)

2010-03-15

356

Low emission internal combustion engine  

Microsoft Academic Search

A low emission, internal combustion compression ignition engine having a cylinder, a piston movable in the cylinder and a pre-combustion chamber communicating with the cylinder near the top thereof and in which low emissions of NO.sub.x are achieved by constructing the pre-combustion chamber to have a volume of between 70% and 85% of the combined pre-chamber and main combustion chamber

Karaba; Albert M

1979-01-01

357

Quasi-steady combustion modeling of homogeneous solid propellants  

SciTech Connect

Classical, linearized quasi-steady (QS) theory of unsteady combustion of homogeneous solid propellants (both pressure- and radiation-driven) is reexamined. Zeroth order, high activation energy (E/RT {much_gt} 1), decomposition is assumed. Many prevailing ideas about condensed-phase pyrolysis are challenged and several misconceptions are corrected. The results show the following: (1) the inadequacy of simple Arrhenius surface pyrolysis; (2) that the common assumption of zero Jacobian ({delta} or n{sub s}) parameter is physically unrealistic for pressure-driven combustion except perhaps in plateau regions; (3) that classical quasi-steady theory is not necessarily incompatible with observed pressure instability [Re{l_brace}R{sub p}{r_brace} > 0] in mesa propellants; (4) that measured steady-state combustion parameters (e.g., E{sub c} = 2E{sub s} = 40 kcal/mol for double base propellant) and quasi-steady theory can model T-burner data reasonably well; (5) that the preexponential parameters in the pyrolysis expression play a critical role in the dynamic response (particularly T{sub 0} and Q{sub c}); (6) that thermal radiation also plays an important role through its effect on the steady state sensitivity parameters, particularly the k (or {sigma}{sub p}) parameter. An approach is outlined for modeling dynamic combustion response based on zeroth order pyrolysis which allows difficult parameters, such as r and {delta} (or A and n{sub s}) to be obtained from relatively easily measured ones, k and v (or B and n), E{sub c}, Q{sub c}, and T{sub s}. An approach for determining these fundamental combustion parameters using radiation-driven unsteady burning tests is described.

Brewster, Q. [Univ. of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering; Son, S.F. [Los Alamos National Lab., NM (United States)

1995-10-01

358

Combustion turbine dynamic model validation from tests  

Microsoft Academic Search

Studies have been conducted on the Alaskan Railbelt System to examine the hydrothermal power system response after the hydroelectric power units at Bradley Lake are installed. The models and data for the generating units for the initial studies were not complete. Typical models were used, but their response appeared to be faster than judged by operating experience. A testing program

L. N. Hannett; Afzal Khan

1993-01-01

359

Computational tools for pulverized-coal combustion. Seventh quarterly report, October 1982December 1982. [Combustion model COMO  

Microsoft Academic Search

The combustion model (COMO) consists of a number of relatively independent modules that represent the major processes involved in pulverized-coal combustion. These modules will be continually upgraded over the course of the contract. During the first quarter, detailed life-of-the-project task descriptions were prepared, literature searches were conducted, and process models were selected. In the second quarter, formulation and coding of

W. J. Oberjohn; D. K. Cornelius; W. A. Fiveland

1983-01-01

360

NUMERICAL MODELING OF TURBULENT FLOW IN A COMBUSTION TUNNEL  

SciTech Connect

A numerical technique for the analysis of turbulent flow associated with combustion is presented, The technique utilizes Chorin's RVM (Random Vortex Method), an algorithm capable of tracing the action of elementary turbulent eddies and their cumulative effects without imposing any restriction upon their motion. In the past RVM has been used with success to treat non-reacting turbulent flows, revealing, in particular, the mechanics of large scale flow patterns, the so-called coherent structures. Introduced here is a flame propagation algorithm, also developed by Chorin, in conjunction with volume sources modeling the mechanical effects of the exothermic process of combustion. As an illustration of its use, the technique is applied to flow in a combustion tunnel where the flame is stabilized by a back-facing step. Solutions for both non-reacting and reacting flow fields are obtained, under the restriction of a set of most stringent idealizations, mimicking nonetheless quite satisfactorily the essential features of turbulent combustion in a lean propane-air mixture that were observed in the laboratory by means of high speed schlieren cinematography.

Ghoniem, A. F.; Chorin, A. J.; Oppenheim, A. K.

1980-09-01

361

Modeling study of a new circulating fluidized bi-bed boiler combustion system  

NASA Astrophysics Data System (ADS)

This paper presents a set of general dynamic mathematical models for the combustion system of a circulating fluidized bi-bed boiler. The models fully consider the flow, combustion and heat transfer characteristics, and describe the physical and chemical processes inside the bi-bed, including the gas-solid flow, multiple particles combustion, gas chemical reactions, heat transfer and pressure balances, etc.

Zhao, Jian; Suo, Yisheng; Cheng, Fangzhen; Zhang, Yong; Gu, Xubin

1999-09-01

362

Modelling spontaneous combustion in wet lignite  

NASA Astrophysics Data System (ADS)

A model of self-heating of wet coal is presented. This involves coupled heat and mass transport within a coal pile, together with an exothermic reaction and phase changes of water. There are four state variables: temperature, oxygen, water vapour and liquid water concentrations. Heat and mass are conducted or diffused through the pile, while simultaneously undergoing chemical reaction. As demonstrated by experiment, the heat release rate depends in a quadratic fashion on the liquid water content and this feature is a distinctive aspect of the model. After development of the model, an illustrative spatially uniform model of just three state variables (temperature, oxygen and liquid water concentrations) is analysed for its bifurcational structure of steady states, periodic solutions and their stability. By this means, thresholds for the onset of ignition can be determined as a function of the physical and chemical parameters.

Gong, Rose; Burnell, John G.; Wake, Graeme C.

1999-06-01

363

Surrogate Model Development for Fuels for Advanced Combustion Engines  

SciTech Connect

The fuels used in internal-combustion engines are complex mixtures of a multitude of different types of hydrocarbon species. Attempting numerical simulations of combustion of real fuels with all of the hydrocarbon species included is highly unrealistic. Thus, a surrogate model approach is generally adopted, which involves choosing a few representative hydrocarbon species whose overall behavior mimics the characteristics of the target fuel. The present study proposes surrogate models for the nine fuels for advanced combustion engines (FACE) that have been developed for studying low-emission, high-efficiency advanced diesel engine concepts. The surrogate compositions for the fuels are arrived at by simulating their distillation profiles to within a maximum absolute error of 4% using a discrete multi-component (DMC) fuel model that has been incorporated in the multi-dimensional computational fluid dynamics (CFD) code, KIVA-ERC-CHEMKIN. The simulated surrogate compositions cover the range and measured concentrations of the various hydrocarbon classes present in the fuels. The fidelity of the surrogate fuel models is judged on the basis of matching their specific gravity, lower heating value, hydrogen/carbon (H/C) ratio, cetane number, and cetane index with the measured data for all nine FACE fuels.

Anand, Krishnasamy [University of Wisconsin, Madison; Ra, youngchul [University of Wisconsin, Madison; Reitz, Rolf [University of Wisconsin; Bunting, Bruce G [ORNL

2011-01-01

364

Combustion Characteristics of Liquid Normal Alkane Fuels in a Model Combustor of Supersonic Combustion Ramjet Engine  

NASA Astrophysics Data System (ADS)

Effect of kinds of one-component n-alkane liquid fuels on combustion characteristics was investigated experimentally using a model combustor of scramjet engine. The inlet condition of a model combustor is 2.0 of Mach number, up to 2400K of total temperature, and 0.38MPa of total pressure. Five kinds of n-alkane are tested, of which carbon numbers are 7, 8, 10, 13, and 16. They are more chemically active and less volatile with an increase of alkane carbon number. Fuels are injected to the combustor in the upstream of cavity with barbotage nitrogen gas and self-ignition performance was investigated. The result shows that self-ignition occurs with less equivalence ratio when alkane carbon number is smaller. This indicates that physical characteristic of fuel, namely volatile of fuel, is dominant for self-ignition behavior. Effect on flame-holding performance is also examined with adding pilot hydrogen and combustion is kept after cutting off pilot hydrogen with the least equivalence ratio where alkane carbon number is from 8 to 10. These points are discussed qualitatively from the conflict effect of chemical and physical properties on alkane carbon number.

??, ?; ??, ??; ??, ??; ??, ???; ??, ??; ??, ??; ??, ??

365

A model for double base propellant combustion  

SciTech Connect

Several models have been developed to predict the burning rate of double base propellant as a function of pressure and initial temperature. The increasingly numerous experimental results (most from Kubota) provide a well established data base which allows one to verify the reliability of the numerical models. A complete model must determine the burning rate vs. pressure, initial temperature, and heat of explosion, in addition, to the temperature profile in both the condensed and gas phases. For example, it is very well known that the DB propellant gas phase sustains two flames. They are separated by a dark zone at low pressure. At high pressure, the secondary flame merges into the primary flame eliminating the dark zone. It is important to take this phenomenon into account in a DB model. The solution of the temperature profile in the gas phase is quite complex. One generally uses a transient numerical method since it is often convenient to determine the steady solution by first solving the transient equations. However, the process can be very cumbersome (especially if the flame is separated or is about to merge). The purpose of this study is to prove that it is possible to simplify the equations of the steady model in order to avoid a very lengthy resolution especially because the computation shows that it is necessary to adjust several parameters to calculate the correct temperature profiles.

Bizot, A.

1987-01-01

366

OTA measurements of wireless stations in reverberation chamber versus anechoic chamber: from accuracy models to testing of MIMO systems  

Microsoft Academic Search

The paper will describe the fundamental characteristics of different wave propagation environments (such as Rayleigh fading, Rice fading, and polarization balance; coherence bandwidth and time delay spread; and fading speed, coherence time and Doppler spread), and relate these characteristics to the Line-Of-Sight (LOS) emulated by good anechoic chambers, and the rich isotropic multipath environment emulated by good reverberation chambers. The

Per-Simon Kildal

2010-01-01

367

Modeling of liquid fuel combustion in fluidized bed  

Microsoft Academic Search

A mathematical model has been developed to simulate combustion of liquid fuel in fluidized bed. The hydrodynamic description of the bed is based on modified two-phase theory of fluidization where the bed is assumed to consist of three phases. A jet-bubble phase which is fuel highly rich bubbles formed at the fuel injector, a distributor-bubble phase which is fuel free

F. Okasha

2007-01-01

368

Combustion characteristics of a model can-type combustor  

Microsoft Academic Search

Combustion characteristics of a model can-type combustor are reported for inlet temperatures of 315 and 523 K at an air-fuel ratio corresponding to that of takeoff conditions, with gaseous fuel and at near-atmospheric pressure. Temperatures were obtained with fine-wire thermocouples, and concentrations of UHC, Hâ, CO, COâ, and Oâ sampled through a water-cooled probe with a flame ionization detector, a

A. F. Bicen; D. G. N. Tse; J. H. Whitelaw

1990-01-01

369

Numerical modelling of turbulent catalytically stabilized channel flow combustion  

Microsoft Academic Search

The turbulent catalytically stabilized combustion of lean hydrogen–air premixtures is investigated numerically in plane channels with platinum-coated isothermal walls. The catalytic wall temperature is 1220K and the incoming mixture has a mean velocity of 15m\\/s and a turbulent kinetic energy of 1.5m2\\/s2. A two-dimensional elliptic model is developed with elementary heterogeneous and homogeneous chemical reactions. The approach is based on

John Mantzaras; Christoph Appel; Peter Benz; Urs Dogwiler

2000-01-01

370

Modeling and Simulation of Combustion in PDE using simplified Chemical Mechanisms  

NASA Astrophysics Data System (ADS)

The detonation phenomenon has been studied for nearly a century for its use in a Pulse Detonation Engine (PDE). It is attractive since it is a fast, constant-volume process, which is more efficient than deflagration, in converting chemical energy to mechanical energy. The combustion phenomenon inside a PDE is being modeled with single-step and simplified multi-step finite-rate reaction mechanisms. Detonation is initiated using two techniques, namely, i) Deflagration to Detonation Transition (DDT) and ii) Direct initiation. Both of these approaches are studied using mixtures of ethylene-oxygen and hydrogen-oxygen. A second-order accurate, finite-volume flow solver with capabilities to model chemical reactions (FLUENT) is used for this purpose. The computational simulation allows for proper visualization of the flame propagation, and provides additional insight into the onset of detonation and its structure. The pressure and temperature time-histories at various points in the combustion chamber are examined in detail. The computational results for ethylene-oxygen mixture are validated with the work of Li and Kailasanath. These results show comparable trends in the pressure profiles inside the tube at various time instants.

Raghupathy, Arun P.; Ghia, Karman; Ghia, Urmila

2004-11-01

371

Modelling NOx emissions of single droplet combustion  

Microsoft Academic Search

An approach for modelling and simulation of the generation of nitrogen oxide (NOx) in the gas phase surrounding single burning droplets is presented. Assuming spherical symmetry (no gravity, no forced convection), the governing equations are derived first. Then simplifications are introduced and it is proven that they are appropriate. The influences of the initial droplet diameter, the ambient conditions, and

Klaus G. Moesl; Joachim E. Schwing; Thomas Sattelmayer

2012-01-01

372

Modelling NOx emissions of single droplet combustion  

Microsoft Academic Search

An approach for modelling and simulation of the generation of nitrogen oxide (NOx) in the gas phase surrounding single burning droplets is presented. Assuming spherical symmetry (no gravity, no forced convection), the governing equations are derived first. Then simplifications are introduced and it is proven that they are appropriate. The influences of the initial droplet diameter, the ambient conditions, and

Klaus G. Moesl; Joachim E. Schwing; Thomas Sattelmayer

2011-01-01

373

Chemical Kinetic Modeling of Hydrogen Combustion Limits  

SciTech Connect

A detailed chemical kinetic model is used to explore the flammability and detonability of hydrogen mixtures. In the case of flammability, a detailed chemical kinetic mechanism for hydrogen is coupled to the CHEMKIN Premix code to compute premixed, laminar flame speeds. The detailed chemical kinetic model reproduces flame speeds in the literature over a range of equivalence ratios, pressures and reactant temperatures. A series of calculation were performed to assess the key parameters determining the flammability of hydrogen mixtures. Increased reactant temperature was found to greatly increase the flame speed and the flammability of the mixture. The effect of added diluents was assessed. Addition of water and carbon dioxide were found to reduce the flame speed and thus the flammability of a hydrogen mixture approximately equally well and much more than the addition of nitrogen. The detailed chemical kinetic model was used to explore the detonability of hydrogen mixtures. A Zeldovich-von Neumann-Doring (ZND) detonation model coupled with detailed chemical kinetics was used to model the detonation. The effectiveness on different diluents was assessed in reducing the detonability of a hydrogen mixture. Carbon dioxide was found to be most effective in reducing the detonability followed by water and nitrogen. The chemical action of chemical inhibitors on reducing the flammability of hydrogen mixtures is discussed. Bromine and organophosphorus inhibitors act through catalytic cycles that recombine H and OH radicals in the flame. The reduction in H and OH radicals reduces chain branching in the flame through the H + O{sub 2} = OH + O chain branching reaction. The reduction in chain branching and radical production reduces the flame speed and thus the flammability of the hydrogen mixture.

Pitz, W J; Westbrook, C K

2008-04-02

374

Four-chamber heart modeling and automatic segmentation for 3D cardiac CT volumes  

NASA Astrophysics Data System (ADS)

Multi-chamber heart segmentation is a prerequisite for quantification of the cardiac function. In this paper, we propose an automatic heart chamber segmentation system. There are two closely related tasks to develop such a system: heart modeling and automatic model fitting to an unseen volume. The heart is a complicated non-rigid organ with four chambers and several major vessel trunks attached. A flexible and accurate model is necessary to capture the heart chamber shape at an appropriate level of details. In our four-chamber surface mesh model, the following two factors are considered and traded-off: 1) accuracy in anatomy and 2) easiness for both annotation and automatic detection. Important landmarks such as valves and cusp points on the interventricular septum are explicitly represented in our model. These landmarks can be detected reliably to guide the automatic model fitting process. We also propose two mechanisms, the rotation-axis based and parallel-slice based resampling methods, to establish mesh point correspondence, which is necessary to build a statistical shape model to enforce priori shape constraints in the model fitting procedure. Using this model, we develop an efficient and robust approach for automatic heart chamber segmentation in 3D computed tomography (CT) volumes. Our approach is based on recent advances in learning discriminative object models and we exploit a large database of annotated CT volumes. We formulate the segmentation as a two step learning problem: anatomical structure localization and boundary delineation. A novel algorithm, Marginal Space Learning (MSL), is introduced to solve the 9-dimensional similarity transformation search problem for localizing the heart chambers. After determining the pose of the heart chambers, we estimate the 3D shape through learning-based boundary delineation. Extensive experiments demonstrate the efficiency and robustness of the proposed approach, comparing favorably to the state-of-the-art. This is the first study reporting stable results on a large cardiac CT dataset with 323 volumes. In addition, we achieve a speed of less than eight seconds for automatic segmentation of all four chambers.

Zheng, Yefeng; Georgescu, Bogdan; Barbu, Adrian; Scheuering, Michael; Comaniciu, Dorin

2008-04-01

375

Information on the EFP-Project Coal-Combustion.  

National Technical Information Service (NTIS)

The purpose of the project is to set up a detailed three-dimensional EDP model of the pulverised-coal combustion process in large combustion chambers. The model will be applicable to the design for boilers, to the evaluation of the suitability of differen...

S. Limkilde Hansen P. Toerslev Jensen H. Jensen L. A. Petersen

1983-01-01

376

INVESTIGATION OF THE FATE OF MERCURY IN A COAL COMBUSTION PLUME USING A STATIC PLUME DILUTION CHAMBER  

SciTech Connect

The overall goal of the project was to further develop and then verify SPDC's ability to determine the physical and chemical transformations of mercury in combustion stack plumes. Specific objectives of the project were to perform controlled tests at the pilot scale using dynamic spiking of known mercury compounds (i.e., Hg{sup 0} and HgCl{sub 2}) to prove the ability of the SPDC to determine the following: whether mercury condenses onto particulate matter in a cooling plume; whether there is reduction of Hg{sup 2+} to Hg{sup 0} occurring in hygroscopic aerosols; whether condensed Hg{sup 2+} on particles is photochemically reduced to Hg{sup 0}; and whether or not the Solid Ontario Hydro mercury speciation method (SOH) provides the same results as the Ontario Hydro (OH) mercury speciation method.

Dennis L. Laudal

2001-11-01

377

Development of a time-scale interaction combustion model and its application to gasoline and diesel engines  

Microsoft Academic Search

The combustion processes of both gasoline and diesel engines are becoming similar, as a result of the application of direct fuel injection to the former and the reduction of the compression ratio of the latter. A novel time-scale interaction (TI) combustion model has been developed for simulating combustion phenomena with high accuracy, ranging from premixed charge combustion to diffusion combustion.

Atsushi Teraji; Yoshihiro Imaoka; Tsuyoshi Tsuda; Toru Noda; Masaaki Kubo; Shuji Kimura

2009-01-01

378

Aeroelasticity Analysis of AN Industrial Gas Turbine Combustor Using a Simplified Combustion Model  

NASA Astrophysics Data System (ADS)

Lean premixed industrial gas turbine combustors are susceptible to flame instabilities, resulting in large unsteady pressure waves that may cause the discharge nozzle to experience excessive vibration levels. A detailed aeroelasticity analysis, aimed at investigating possible structural failure mechanisms, was undertaken using a time-accurate unsteady flow representation, a simplified combustion disturbance and a structural model of the discharge nozzle. The computational domain included the lower part of the combustor geometry as well as the nozzle guide vanes (NGVs) at the HP turbine inlet. A pressure perturbation, representing the unsteadiness due to the combustion process, was applied below the tertiary fuel inlet and its frequency was set to each structural natural frequency in turn. The propagation of the pressure perturbation through the combustor nozzle, its reflection from the NGVs and further reflections were monitored using two different models. The first one, the so-called ``open'' system, ignored the reflections from the upper part of the combustion chamber while the second one, the ``closed'' system, assumed full reflection with an appropriate time shift. The calculations have shown that the imposed excitation could generate unsteady pressure shapes that were correlated with the ``flap'' modes of the discharge nozzle. In addition, an acoustic resonance condition was observed when the forcing pressure wave had a frequency close to 550 Hz, the experimentally observed failure frequency of the nozzle. The co-existence of these two factors, i.e., excitation/structural-mode match and the possibility of acoustic resonance, was thought to have the potential of producing very high vibration response.

Bréard, C.; Sayma, A. I.; Vahdati, M.; Imregun, M.

2002-12-01

379

Transient Spray Combustion Computations.  

National Technical Information Service (NTIS)

Many practical combustion devices involves direct injection of liquid fuel into the combustion chamber, e.g., gas turbine engines, diesel engines, rockets and ramjet engines, and furnaces. Typically, the fuel is of sufficiently low volatility that vaporiz...

W. A. Sirignano

1986-01-01

380

A subgrid mixing model for LES of nonpremixed turbulent combustion  

SciTech Connect

A new sub-grid mixing model for use in large eddy simulations of turbulent combustion is presented and applied to a hydrogen-air diffusion flame. The sub-grid model is based on Kerstein's Linear Eddy Model (1988). The model is first used to predict the mixing of a conserved scalar in a turbulent shear flow. The model correctly predicts the behavior of the pdf of the scalar field and displays a nonmarching peak at the preferred mixture fraction as the shear layer is traversed. It is then illustrated how a reduced chemical mechanism can be implemented within the linear eddy subgrid model formulation. The model is used to predict NO formation in hydrogen-air diffusion flame using a reduced chemical mechanism involving nine reactive scalars. 14 refs.

Mcmurtry, P.A.; Menon, S.; Kerstein, A.R. (Utah, University, Salt Lake City (United States) Quest Integrated, Inc., Kent, Wn (United States) Sandia National Laboratories, Livermore, CA (United States))

1992-01-01

381

Improvement of Coal Combustion Efficiency and Decrease of Harmful Emission Under the Influence of Plasma - Modelling  

Microsoft Academic Search

A numerical study has been undertaken which simulates the process of pulverised coal preparation for combustion using plasmas. Two combustion model s ('fast chemistry' based on one-step fuel transformation into final products, and 'stretched laminar flamelets' with the detailed chemical mechanism for the combust ion of volatiles) are tested and validated with the experimental results. In a preliminary calc ulation,

Z. Jankoski

382

Macrokinetics of Combustion of Monodisperse Agglomerates in the Flame of a Model Solid Propellant  

Microsoft Academic Search

The paper describes a procedure for studying the macrokinetics of combustion of agglomerates in a solid propellant flame using special samples of a model propellant generating monodisperse agglomerates. Empirical dependences of the incompleteness of aluminum combustion in the combustion products of a propellant based on ammonium perchlorate and HMX on time and pressure were established. The mass fraction of oxide

O. G. Glotov; V. E. Zarko; V. V. Karasev; T. D. Fedotova; A. D. Rychkov

2003-01-01

383

Combustion Species Sampling.  

National Technical Information Service (NTIS)

A combustion chamber for propellant studies was developed and molecular beam gas sampling systems were analyzed in this program. A unique laboratory combustor design provides sampling from any part of the chamber by axial movement of a gas extraction port...

J. Kahrs

1968-01-01

384

Multidimensional modeling of diesel ignition and combustion using a multistep kinetics model  

SciTech Connect

Ignition and combustion mechanisms in diesel engines were studied using the KIVA code, with modifications to the combustion, heat transfer, crevice flow, and spray models. A laminar-and-turbulent characteristic-time combustion model that has been used successfully for spark-ignited engine studies was extended to allow predictions of ignition and combustion in diesel engines. A more accurate prediction of ignition delay was achieved by using a multistep chemical kinetics model. The Shell knock model was implemented for this purpose and was found to be capable of predicting successfully the autoignition of homogeneous mixtures in a rapid compression machine and diesel spray ignition under engine conditions. The physical significance of the model parameters is discussed and the sensitivity of results to the model constants is assessed. The ignition kinetics model was also applied to simulate the ignition process in a Cummins diesel engine. The post-ignition combustion was simulated using both a single-step Arrhenius kinetics model and also the characteristic-time model to account for the energy release during the mixing-controlled combustion phase. The present model differs from that used in earlier multidimensional computations of diesel ignition in that it also includes state-of-the-art turbulence and spray atomization models. In addition, in this study the model predictions are compared to engine data. It is found that good levels of agreement with the experimental data are obtained using the multistep chemical kinetics model for diesel ignition modeling. However, further study is needed of the effects of turbulent mixing on post-ignition combustion.

Kong, S.C.; Reitz, R.D. (Univ. of Wisconsin, Madison, WI (United States). Dept. of Mechanical Engineering)

1993-10-01

385

Structure-Based Predictive model for Coal Char Combustion.  

SciTech Connect

During the third quarter of this project, progress was made on both major technical tasks. Progress was made in the chemistry department at OSU on the calculation of thermodynamic properties for a number of model organic compounds. Modelling work was carried out at Brown to adapt a thermodynamic model of carbonaceous mesophase formation, originally applied to pitch carbonization, to the prediction of coke texture in coal combustion. This latter work makes use of the FG-DVC model of coal pyrolysis developed by Advanced Fuel Research to specify the pool of aromatic clusters that participate in the order/disorder transition. This modelling approach shows promise for the mechanistic prediction of the rank dependence of char structure and will therefore be pursued further. Crystalline ordering phenomena were also observed in a model char prepared from phenol-formaldehyde carbonized at 900{degrees}C and 1300{degrees}C using high-resolution TEM fringe imaging. Dramatic changes occur in the structure between 900 and 1300{degrees}C, making this char a suitable candidate for upcoming in situ work on the hot stage TEM. Work also proceeded on molecular dynamics simulations at Boston University and on equipment modification and testing for the combustion experiments with widely varying flame types at Ohio State.

Hurt, R.; Colo, J [Brown Univ., Providence, RI (United States). Div. of Engineering; Essenhigh, R.; Hadad, C [Ohio State Univ., Columbus, OH (United States). Dept. of Chemistry; Stanley, E. [Boston Univ., MA (United States). Dept. of Physics

1997-09-24

386

Reverberation chamber field modeling for application to the source stirring technique  

Microsoft Academic Search

The paper describes an analytical model applied to study the behavior of an antenna moving inside a resonant cavity. It is the basic step to develop a source stirring mode reverberation chamber (RC). The model is able to account for the different coupling of the source with the many cavity modes. The results obtained for a simple dipole are used

G. Cerri; V. Mariani Primiane; P. Russo

2010-01-01

387

MODELS AND STATISTICAL METHODS FOR GASEOUS EMISSION TESTING OF FINITE SOURCES IN WELL-MIXED CHAMBERS  

EPA Science Inventory

The paper proposes two families of mathematical models to represent either the concentration of a gaseous emission in (or the accumulated amount exiting from) a well-mixed, environmentally controlled test chamber. A thin film model, which seems applicable to such sources as carpe...

388

Energy Model of Increasing Radiation and the Size of an Electron Avalanche in a Streamer Chamber.  

National Technical Information Service (NTIS)

A qualitative model is proposed of increasing light radiation and the size of an avalanche with increased gas amplification N in a streamer chamber based on the proportion of the light radiation of electrostatic avalanche energy. From the model it follows...

N. S. Glagoleva A. T. Matyushin V. T. Matyushin N. N. Nupgozhin

1983-01-01

389

Matching conditional moments in PDF modelling of nonpremixed combustion  

SciTech Connect

The rate of generation of fluctuations with respect to the scalar values conditioned on the mixture fraction, which significantly affects turbulent nonpremixed combustion processes, is examined. Simulation of the rate in a major mixing model is investigated and the derived equations can assist in selecting the model parameters so that the level of conditional fluctuations is better reproduced by the models. A more general formulation of the multiple mapping conditioning (MMC) model that distinguishes the reference and conditioning variables is suggested. This formulation can be viewed as a methodology of enforcing certain desired conditional properties onto conventional mixing models. Examples of constructing consistent MMC models with dissipation and velocity conditioning as well as of combining MMC with large eddy simulations (LES) are also provided.

Klimenko, A.Y. [Mechanical Engineering Division, The University of Queensland, Qld 4072 (Australia)

2005-12-01

390

Evaluation of a hybrid kinetics/mixing-controlled combustion model for turbulent premixed and diffusion combustion using KIVA-2  

SciTech Connect

Two dimensional calculations were made of spark ignited premixed-charge combustion and direct injection stratified-charge combustion in gasoline fueled piston engines. Results are obtained using kinetic-controlled combustion submodel governed by a four-step global chemical reaction or a hybrid laminar kinetics/mixing-controlled combustion submodel that accounts for laminar kinetics and turbulent mixing effects. The numerical solutions are obtained by using KIVA-2 computer code which uses a kinetic-controlled combustion submodel governed by a four-step global chemical reaction (i.e., it assumes that the mixing time is smaller than the chemistry). A hybrid laminar/mixing-controlled combustion submodel was implemented into KIVA-2. In this model, chemical species approach their thermodynamics equilibrium with a rate that is a combination of the turbulent-mixing time and the chemical-kinetics time. The combination is formed in such a way that the longer of the two times has more influence on the conversion rate and the energy release. An additional element of the model is that the laminar-flame kinetics strongly influence the early flame development following ignition.

Nguyen, H.L.; Wey, Mingjyh.

1990-01-01

391

Evaluation of a hybrid kinetics/mixing-controlled combustion model for turbulent premixed and diffusion combustion using KIVA-2  

NASA Astrophysics Data System (ADS)

Two dimensional calculations were made of spark ignited premixed-charge combustion and direct injection stratified-charge combustion in gasoline fueled piston engines. Results are obtained using kinetic-controlled combustion submodel governed by a four-step global chemical reaction or a hybrid laminar kinetics/mixing-controlled combustion submodel that accounts for laminar kinetics and turbulent mixing effects. The numerical solutions are obtained by using KIVA-2 computer code which uses a kinetic-controlled combustion submodel governed by a four-step global chemical reaction (i.e., it assumes that the mixing time is smaller than the chemistry). A hybrid laminar/mixing-controlled combustion submodel was implemented into KIVA-2. In this model, chemical species approach their thermodynamics equilibrium with a rate that is a combination of the turbulent-mixing time and the chemical-kinetics time. The combination is formed in such a way that the longer of the two times has more influence on the conversion rate and the energy release. An additional element of the model is that the laminar-flame kinetics strongly influence the early flame development following ignition.

Nguyen, H. Lee; Wey, Ming-Jyh

392

A fractal dynamic SGS combustion model for turbulent premixed flames  

NASA Astrophysics Data System (ADS)

A dynamic subgrid scale (SGS) combustion model for large eddy simulation (LES) of turbulent premixed combustion has been developed based on the fractal characteristics of turbulent premixed flames and the scale separation of turbulence. This model locally predicts the fractal dimension of a flame surface and the local flame surface area. To give the lower limit of the flame surface area, the contribution of dilatation across the flame is also considered. The local turbulent flame speed is then determined supposing the flamelet concept. In the model formulation, the Kolmogorov length scale is described with the grid scale (GS) variables to yield the inner-cutoff of the flame surface. It is achieved by assuming that, in high Reynolds number turbulence, most of the turbulence energy is dissipated in the SGS level and the dissipation balances with the energy production that is given by an SGS turbulence model. A series of static tests have been performed to examine the model by filtered data of direct numerical simulation (DNS). Gaussian or tophat filters with different widths within the range of the inner- and outer-cutoffs of the flame surface are applied as the LES and the test- filters. The results show that the predicted flame surface area agrees well with that extracted from the DNS data regardless of the filter type and the widths.

Yoshikawa, Itaru; Shim, Youngsam; Tanahashi, Mamoru; Miyauchi, Toshio

2011-11-01

393

Complex Wall Boundary Conditions for Modeling Combustion in Catalytic Channels  

NASA Astrophysics Data System (ADS)

Monolith catalytic reactors for exothermic oxidation are being used in automobile exhaust clean-up and ultra-low emissions combustion systems. The reactors present a unique coupling between mass, heat, and momentum transport in a channel flow configuration. The use of porous catalytic coatings along the channel wall presents a complex boundary condition when modeled with the two-dimensional channel flow. This current work presents a 2-D transient model for predicting the performance of catalytic combustion systems for methane oxidation on Pd catalysts. The model solves the 2-D compressible transport equations for momentum, species, and energy, which are solved with a porous washcoat model for the wall boundary conditions. A time-splitting algorithm is used to separate the stiff chemical reactions from the convective/diffusive equations for the channel flow. A detailed surface chemistry mechanism is incorporated for the catalytic wall model and is used to predict transient ignition and steady-state conversion of CH4-air flows in the catalytic reactor.

Zhu, Huayang; Jackson, Gregory

2000-11-01

394

A comparison of flamelet models for premixed turbulent combustion  

SciTech Connect

Five flamelet models for premixed turbulent combustion are described and compared in the case of a one-dimensional turbulent flame propagating in frozen turbulence. This simple configuration allows analytical solution (KPP) to be obtained as devised by Kolmogorov, Petrovski, and Piskunov and performed by Hakberg and Gosman. The explicit solution obtained by this analysis provides the turbulent flame speed as a function of the model parameters and of the turbulence characteristics. These results are compared with experimental data of Abdel-Gayed et al. and with results obtained with the classical eddy break-up model. The realizability of the models is also studied. Recent models based on direct numerical simulation results correctly predict the bending'' of the turbulent burning velocity U[sub [tau

Duclos, J.M.; Veynante, D. (CNRS, Paris (France). Lab. EM2C); Poinsot, T. (Inst. de Mecanique des Fluides, Toulouse (France))

1993-10-01

395

Numerical simulation of syngas combustion with a multi-spark ignition system in a diesel engine adapted to work at the Otto cycle  

Microsoft Academic Search

This work focuses on the construction of a 2D dynamic model, taking into consideration the turbulent flux combustion reactions of syngas inside a combustion chamber and its displacement through the cylinder of a diesel engine model OM 447 LA converted to Otto cycle operation. The engine has a multi-spark ignition system. The geometry of both the chamber and cylinder is

B. Gamiño; J. Aguillón

2010-01-01

396

A continuous surface regression model for the combustion of composite solid propellants  

Microsoft Academic Search

This paper describes a new approach at modeling the combustion of solid composite propellants. Earlier attempts at modeling the steady-state burning of solid propellants have approached the modeling of composite solid propellant combustion by assuming an unchanging, average surface geometry for the oxidizer and fuel. The Continuous Oxidizer Regression (COR) model allows the oxidizer burn at a rate different from

J. J. Cor; J. P. Renie

1987-01-01

397

Unified multilayer diffusion model and application to diffusion experiment in porous media by method of chambers.  

PubMed

Diffusion coefficient is an important parameter for examining contaminant transport in the environment. Chamber methods (with or without external mixing devices) are the most popular methods for measuring effective diffusion coefficients in porous media (Deff) through air or water. The objectives of this paper were to apply simplified and unified analytical methods for both perfectly mixed and nonmixed (one- or two-) chamber systems and to examine how mixing affects the estimation of Deff. An analytical solution for a multilayer transient diffusion model was applied to the chamber methods without external mixing. By increasing the diffusion coefficient in reservoirs (D1 and D3) more than 10 times from the value for air or water (D0), the model was sufficient to approximate the well-mixed condition and, consequently, can be used to model transient diffusion in chamber systems with external mixing devices. We demonstrated that at long time Deff was related to the first eigenvalue (beta1) of a transcendental equation, which provided a quick method for determining Deff accurately from experimental data. The error caused by using the well-mixed approximation can be significant for a single-chamber system when there are no external mixing devices. This error increased rapidly with decreases in the experimental duration. A good fit for the concentration versus time curve could not be obtained forthe well-mixed solution, especially when sampling ports were near the boundary (x=0) and interface (x = l1). The proposed solutions are useful when the reservoir or chamber methods are used for measuring Deff and have wide applications in predicting contaminates transport in porous media and groundwater. PMID:19452895

Liu, Gang; Barbour, Lee; Si, Bing C

2009-04-01

398

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: CARS study of linewidths of the Q-branch of hydrogen molecules at high temperatures in a pulsed high-pressure H2—O2 combustion chamber  

NASA Astrophysics Data System (ADS)

The results of measurements of individual line widths of the Q-branch of a hydrogen molecule and the corresponding coefficients of broadening caused by collisions with water molecules at T = 2700 K in a repetitively pulsed high-pressure (50-200 atm) hydrogen-oxygen combustion chamber are presented. CARS spectra of individual Q1—Q7 hydrogen lines, pressure pulses, and the broadband CARS spectra of the entire Q-branch of hydrogen are recorded simultaneously during a single laser pulse. The shape of line profiles was analysed using a Fabry—Perot interferometer. The temperature in the volume being probed was determined from the 'broadband' CARS spectra. The entire body of the experimental results gives information on the spectral linewidths, temperature and pressure in the combustion chamber during CARS probing.

Vereschagin, Konstantin A.; Vereschagin, Alexey K.; Clauss, W.; Klimenko, D. N.; Oschwald, M.; Smirnov, Valery V.; Stelmakh, O. M.; Fabelinskii, V. I.

2005-03-01

399

Simulation of the turbulent flow inside the combustion chamber of a reciprocating engine with a finite element method  

SciTech Connect

This paper presents numerical simulations of turbulent flows during the intake and the compression strokes of a model engine. The Favre average Navier-Stokes equations are solved with a k-[epsilon] turbulence model. The numerical procedure uses a time dependent semi-implicit scheme and a finite element method with a moving mesh. Results of 2-D axisymmetrical calculations with and without inlet swirl are presented and compared to experimental data. The influence of different turbulence models and the numerical precision of the simulations are also discussed.

Mao, Y.; Buffat, M.; Jeandel, D. (CNRS, Ecully (France). Lab. de Mecanique des Fluides et Acoustique)

1994-06-01

400

Reverberation Chamber for Antenna Measurements: Modeling Using Method of Moments, Spectral Domain Techniques, and Asymptote Extraction  

Microsoft Academic Search

Large reverberation chambers (RCs) have proved to be useful for measuring the performance of small antennas and terminals for wireless communications, and it is therefore important to be able to model them numerically to control accuracy. This paper describes a method of moments approach for analyzing wire antennas and other metallic objects in a large RC. The RC is treated

Kristian Karlsson; Jan Carlsson; Per-Simon Kildal

2006-01-01

401

Kinetic Modeling of Combustion Characteristics of Real Biodiesel Fuels  

SciTech Connect

Biodiesel fuels are of much interest today either for replacing or blending with conventional fuels for automotive applications. Predicting engine effects of using biodiesel fuel requires accurate understanding of the combustion characteristics of the fuel, which can be acquired through analysis using reliable detailed reaction mechanisms. Unlike gasoline or diesel that consists of hundreds of chemical compounds, biodiesel fuels contain only a limited number of compounds. Over 90% of the biodiesel fraction is composed of 5 unique long-chain C{sub 18} and C{sub 16} saturated and unsaturated methyl esters. This makes modeling of real biodiesel fuel possible without the need for a fuel surrogate. To this end, a detailed chemical kinetic mechanism has been developed for determining the combustion characteristics of a pure biodiesel (B100) fuel, applicable from low- to high-temperature oxidation regimes. This model has been built based on reaction rate rules established in previous studies at Lawrence Livermore National Laboratory. Computed results are compared with the few fundamental experimental data that exist for biodiesel fuel and its components. In addition, computed results have been compared with experimental data for other long-chain hydrocarbons that are similar in structure to the biodiesel components.

Naik, C V; Westbrook, C K

2009-04-08

402

Diesel engine emissions and combustion predictions using advanced mixing models applicable to fuel sprays  

Microsoft Academic Search

An advanced mixing model was applied to study engine emissions and combustion with different injection strategies ranging from multiple injections, early injection and grouped-hole nozzle injection in light and heavy duty diesel engines. The model was implemented in the KIVA-CHEMKIN engine combustion code and simulations were conducted at different mesh resolutions. The model was compared with the standard KIVA spray

Neerav Abani; Rolf D. Reitz

2010-01-01

403

Equipment, technology, perspectives and modeling of pulse combustion drying  

Microsoft Academic Search

The paper presents the analysis of potential and real benefits of pulse combustion process applied in drying. The phenomenon of pulse combustion, its mechanism, pulse combustors designs, advantages and disadvantages of this technology were described and reviewed. Pulse combustion applications in industry were analyzed and evaluated. Experimental investigations carried out at the Faculty of Process and Environmental Engineering, Technical University

Ireneusz Zbicinski

2002-01-01

404

MODELING NON-EQUILIBRIUM CO OXIDATION IN COMBUSTION SYSTEMS  

Microsoft Academic Search

Performance of industrial and utility combustion systems is becoming increasingly affected by limits on pollutant emissions such as NOx and CO. CO emissions impact design and operation of combustion systems, particularly when coupled with NOx reduction technologies that involve lower temperature operation or staged firing. Lower combustion temperatures or delayed mixing of fuel and air helps minimize NOx formation, but

Bradley R. Adams; Marc A. Cremer; Dave H. Wang

2000-01-01

405

THERMALNET - WP2F: SCIENCE AND MODELING REPORT N.2 - MODELING THE GASIFICATION\\/COMBUSTION  

Microsoft Academic Search

The state of the art is discussed of transport models for combustion and\\/or gasifi- cation of single biomass\\/wood particles. A first group of models assumes that the stages of particle devolatilization and char conversion are sequential, where the description of the first stage is usually highly simplified. Models are also available for the sequential occurrence of the various processes of

406

The application of new combustion and turbulence models to H[sub 2]-air nonpremixed supersonic combustion  

SciTech Connect

Finite reaction rate effects and dilatation effects are explored using an extended laminar flamelet model and turbulence models including dilatation processes. For the H[sub 2]-air nonpremixed turbulent combustion experiment conducted by Evans et al. in a high-speed shear flow, the flamesheet model can reasonably predict the combustion region but fails to predict the profiles of mass fractions, especially for H[sub 2] near the jet axis and O[sub 2] close to the jet edge. The inclusion of both dilatation dissipation and pressure dilatation leads to no significant improvement of the simulation results in this relatively low Mach number test case. The results predicted by the laminar flamelet model dramatically improve the profiles of species mass fractions. This indicates that the high turbulent strain rate usually observed in high-speed flow has a significant influence on the turbulent combustion. The widely used assumptions, such as fast chemical reaction rate, and unity Prandtl and Lewis numbers, are not suitable for this high-speed turbulent flow. It is necessary to include effects of kinetic energy changes in the calculations. Numerical results also show that this supersonic nonpremixed turbulent combustion flow satisfies the criteria of the laminar flamelet model.

Zheng, L.L.; Bray, K.N.C. (Cambridge Univ. (United Kingdom). Dept. of Engineering)

1994-11-01

407

Measurements and Modeling of Combustion Dynamics for Control of Combustion Instabilities.  

National Technical Information Service (NTIS)

This report is the final report of a six-month program with a six- month NCE comprising experimental work on problems arising with unsteady combustion of gases intended for use in propulsion systems. The experimental work comprises measurements providing ...

F. E. Culick A. Ratner D. M. Kang K. I. Matveev W. Pun

2004-01-01

408

Combustion systems  

SciTech Connect

This patent describes an external combustion engine such as a Stirling engine and the like, having an external heat system housing in which is defined a heater space, a hollow liner formed of a ceramic material disposed in the heater space and defining a combustion chamber. Biasing means are coupled to a first end of the liner and coupled with the housing so as to maintain the liner in the heater space while dampening transmission of vibration in the housing to the liner.

Kralick, J.

1986-03-04

409

Group combustion of a cylindrical cloud of char/carbon particles. [Particulates and clouds spherical and cylindrical models  

SciTech Connect

Extensive experiments were carried out in the past in order to obtain kinetics data on the pyrolysis of coal particles and the char reactions. The literature survey distinctively reveals two kinds of studies: (i) Individual Particle Combustion (IPC) and (ii) Combustion of Particle Streams or Clouds. The experimental data obtained with particle streams are normally interpreted using IPC models with the a priori assumption that the cloud is dilute. But the term ''dilute'' is rarely quantified and justified considering the collective behavior of a cloud of particles. The group combustion model accounts for the reduction in burning rate due to the collective behavior of a large number of particles. While the spherical group combustion model may be employed for coal/char spray combustion modeling, the cylindrical group combustion model is more useful in interpreting the experimental data obtained with a monosized stream of particles. Hence a cylindrical group combustion model is presented here. As in the case of spherical group combustion models, there exist three modes of combustion: (i) Individual Particle Combustion (IPC), (ii) Group Combustion (GC), and (iii) Sheath Combustion (SC). Within the range of parameters studied, it appears that the cylindrical and spherical cloud combustion models yield similar results on nondimensional cloud burning rates and on the combustion modes of a cloud of particles. The results from group theory are then used to identify the mode of combustion (IPC, GC, or SC) and to interpret the experimental data.

Annamalai, K.; Ramalingam, S.; Dahdah, T.; Chi, D.

1988-02-01

410

Analysis of forward combustion underground coal gasification models  

SciTech Connect

A survey has been made of forward combustion gasification models that are available in the public domain. The six models obtained for study have been mathematically analyzed to determine their conceptual completeness and computational complexity. The models range in scope of generality from a simple constrained mass balance model to a two-dimensional unsteady-state model. The computer code for each model has been implemented on the University of Wyoming CDC CYBER 730/760 computer system. Computed analyses with each of the programs are compared using data (taken primarily from the Lawrence Livermore National Laboratory (LLNL) Underground Coal Gasification (UCG) Data Base) corresponding to six representative DOE sponsored field experiments at Hanna, Hoe Creek, Rawlins, and Pricetown. Four of the field tests were air injection experiments and two were oxygen/steam injection experiments. This study provides a direct comparison of input data requirements and computer resource requirements of the six computer codes. It furnishes an indication of the applicability of each model to the various operating conditions in the different field tests. Computational capabilities and limitations of each model are discussed in detail. 20 references, 47 figures, 13 tables.

Fausett, L.K.; Fausett, D.W.

1984-01-01

411

Matematical modelling of straw bale combustion in cigar burners  

SciTech Connect

This paper describes a computer model for the calculation of the steady and non-steady behaviour of straw bales subject to surface combustion in cigar burners. The mathematical formulation is one-dimensional and the flow of gas through the straw bales is described by means of Darcy`s law for flow through a porous medium. The computer model is able to predict flow rate, temperature and composition of gas and straw as function of axial length and time. Calculated results are compared to measurements of temperature and gas composition profiles within the burning straw bales. It is observed that the straw bale temperatures as well as the outlet gas composition are predicted reasonably well. Calculations have been carried out in order to assess the implication of a straw bale feed stop in a 3 MW district heating plant fueled with Heston straw bales. The results indicate serious disturbances in the performance of the burner.

Bech, N. [Riso National Lab., Roskilde (Denmark); Germann, L. [Danish Technological Inst., Arhus (Denmark); Wolff, L. [I/S Vestkraft, Esbjerg (Denmark)

1995-12-31

412

The Magma Chamber Simulator: A Comprehensive Tool for Modeling the Evolution of Magmatic Systems  

Microsoft Academic Search

The Magma Chamber Simulator (MCS) is a computational tool for modeling the chemical and physical evolution of magmatic systems. Closed-system fractional or equilibrium crystallization as well as open-system processes such as assimilation of wallrock partial melt, equilibration of stoped country rock, magma recharge, and eruption are incorporated self-consistently by combining results from the thermodynamic model of Ghiorso &Sack (1995, i.e.

W. A. Bohrson; F. J. Spera; M. S. Ghiorso; S. J. Fowler

2006-01-01

413

Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber  

Microsoft Academic Search

A sectional atmospheric chemistry and aerosol dynamics box model (AEROFOR) was further devel- oped and used to simulate ultra-fine particle formation and growth from seaweed in a chamber flushed with particle-free atmospheric air. In the model, thermodynamically stable clusters were formed by dimer nucleation of OIO vapour, whose precursor was assumed to be molecular I2 emitted by seaweed. Fractal geometry

414

Magma chamber properties from integrated seismic tomography and thermal modeling at Montserrat  

NASA Astrophysics Data System (ADS)

It is widely believed that andesitic magmas erupted at arc-volcanoes are stored in shallow reservoirs prior to eruption, but high-resolution images of focused regions of magma in the shallow crust are rare. We integrate seismic tomography with numerical models of magma chamber growth to constrain the magma chamber beneath Soufrière Hills Volcano, Montserrat. Our approach reveals the characteristics and dynamics of the magmatic system with a level of detail that no single method has yet achieved. The integrated analysis suggests that a magma chamber of 13 km3with over 30% melt fraction formed between 5.5 and at least 7.5 km depth, a significantly higher melt fraction than inferred from the seismic data alone. The magma chamber may have formed by incremental sill intrusion over a few thousand years and is likely to be a transient, geologically short-lived feature. These volume and geometry estimates are critical parameters to model eruption dynamics, which in turn are key to hazard assessment and eruption forecasting.

Paulatto, M.; Annen, C.; Henstock, T. J.; Kiddle, E.; Minshull, T. A.; Sparks, R. S. J.; Voight, B.

2012-01-01

415

A spray-suppression model for turbulent combustion  

SciTech Connect

A spray-suppression model that captures the effects of liquid suppressant on a turbulent combusting flow is developed and applied to a turbulent diffusion flame with water spray suppression. The spray submodel is based on a stochastic separated flow approach that accounts for the transport and evaporation of liquid droplets. Flame extinguishment is accounted for by using a perfectly stirred reactor (PSR) submodel of turbulent combustion. PSR pre-calculations of flame extinction times are determined using CHEMKIN and are compared to local turbulent time scales of the flow to determine if local flame extinguishment has occurred. The PSR flame extinguishment and spray submodels are incorporated into Sandia's flow fire simulation code, VULCAN, and cases are run for the water spray suppression studies of McCaffrey for turbulent hydrogen-air jet diffusion flames. Predictions of flame temperature decrease and suppression efficiency are compared to experimental data as a function of water mass loading using three assumed values of drop sizes. The results show that the suppression efficiency is highly dependent on the initial droplet size for a given mass loading. A predicted optimal suppression efficiency was observed for the smallest class of droplets while the larger drops show increasing suppression efficiency with increasing mass loading for the range of mass loadings considered. Qualitative agreement to the experiment of suppression efficiency is encouraging, however quantitative agreement is limited due to the uncertainties in the boundary conditions of the experimental data for the water spray.

DESJARDIN,PAUL E.; TIESZEN,SHELDON R.; GRITZO,LOUIS A.

2000-02-14

416

Low-frequency combustion oscillations in a model afterburner  

SciTech Connect

Low-frequency combustion oscillations, involving the interaction between longitudinal acoustic waves and unsteady combustion, are investigated for a model afterburner. An experimental rig, in which a confined flame is stabilized in the wake of a conical gutter, is run with inlet conditions representative of an engine afterburner. Results are presented for inlet Mach numbers in the range of 0.15--0.27, with inlet temperatures up to 630 K. Comparison is made between theory and experiment. Although the theory was developed from low Mach number data, it is found to apply equally well at these faster flow rates. The theory is able to predict the frequency of the instability and the mode shape, accurately reproducing the changes due to variations in the inlet Mach number and temperature. The effect of altering the downstream boundary condition by replacing the open end by a choked nozzle is also investigated. Such a change is found to be highly destabilizing, both experimentally and theoretically. Again, predictions from the theory are in good agreement with the observations.

Macquisten, M.A.; Dowling, A.P. (Cambridge Univ. Engineering Dept., Cambridge (United Kingdom))

1993-08-01

417

Measurements of a 1/4-scale model of a 60-kg explosives firing chamber  

SciTech Connect

In anticipation of increasingly stringent environmental regulations, Lawrence Livermore National Laboratory (LLNL) proposes to construct a 60-kg firing chamber to provide blast-effects containment for, most of its open-air, high-explosive, firing operations. Even though these operations are within current environmental limits, containment of the blast effects and hazardous debris will further drastically reduce emissions to the environment and minimize the generated hazardous waste. The major design consideration of such a chamber is its overall structural dynamic response in terms of long-term containment of all blast effects from repeated internal detonations of high explosives. Another concern is how much other portions of the facility must be hardened to ensure personnel protection in the event of an accidental detonation. To assess these concerns, a 1/4-scale replica model of the planned contained firing chamber was designed, constructed, and tested with scaled explosive charges ranging from 25 to 125% of the operational explosives limit of 60 kg. From 16 detonations of high explosives, 880 resulting strains, blast pressures, and temperatures within the model were measured. Factors of safety for dynamic yield of the firing chamber structure were calculated and compared to the design criterion of totally elastic response. The rectangular, reinforced-concrete chamber model exhibited a lightly damped vibrational response that placed the structure in alternating cycles of tension and compression. During compression, both the reinforcing steel and the concrete remained elastic. During tension, the reinforcing steel remained elastic, but the concrete elastic limit was exceeded in two areas, the center spans of the ceiling and the north wall, where elastic safety factors as low as 0.66 were obtained, thus indicating that the concrete would be expected to crack in those areas. Indeed, visual post-test inspection of those areas revealed tight cracks in the concrete.

Pastrnak, J.W.; Baker, C.F.; Simmons, L.F.

1995-01-27

418

Incorporating advanced combustion models to study power density in diesel engines  

NASA Astrophysics Data System (ADS)

A new combustion model is presented that can be used to simulate the diesel combustion process. This combustion process is broken into three phases: low temperature ignition kinetics, premixed burn and high temperature diffusion burn. The low temperature ignition kinetics are modeled using the Shell model. For combustion limited by diffusion, a probability density function (PDF) combustion model is utilized. In this model, the turbulent reacting flow is assumed to be an ensemble of locally laminar flamelets. With this methodology, species mass fractions obtained from the solution of laminar flamelet equations can be conditioned to generate a flamelet library. For kinetically limited (premixed) combustion, an Arrhenius rate is used. To transition between the premixed and diffusion burning modes, a transport equation for premixed fuel was implemented. The ratio of fuel in a computational cell that is premixed is used to determine the contribution of each combustion mode. Results show that this combustion model accurately simulates the diesel combustion process. Furthermore, the simulated results are in agreement with the recent conceptual picture of diesel combustion based upon experimental observations. Large eddy simulation (LES) models for momentum exchange and scalar flux were incorporated into the KIVA solver. In this formulation, the turbulent viscosity, ?t, is determined as a function of the sub- grid turbulent kinetic energy, which is in turn determined from a one equation model. The formulation for the scalar transfer coefficient, ?s, is similar to that of the turbulent viscosity, yet is made to be consistent with scalar transport. Test cases were run verifying that both momentum and scalar flux can be accurately predicted using LES. Once verified, these LES models were used to simulate the diesel combustion process for a Caterpillar 3400 series engine. Results for the engine simulations were in good agreement with experimental data.

Lee, Daniel Michael

419

Computer combustion-radiation model of RDF boilers at Columbus, Ohio  

SciTech Connect

A computer model based on the Columbus, Ohio RDF (refuse derived fuel) furnace system has been developed. The model simulates combustion and radiation heat transfers in the furnace. Variables evaluated were: Arrhenius combustion factors, turbulent mixing factor, radiation blackening factor, air/fuel ratio, and Bragg stirred reactor height. Results provide design evaluation criteria. 8 refs.

Kadunc, D.A.; Essenhigh, R.H.

1982-01-01

420

Analytical Models of the Rupture of the Walls of Magma Chambers: a Critical Review  

NASA Astrophysics Data System (ADS)

Although analytical models commonly involve several simplifications and idealizations to be solved, their importance resides in that they offer benchmarks that can be used to calibrate the more sophisticated treatments (commonly numerical) that are required to solve more realistic situations. For this reason, it is of paramount importance to be sure that analytical models accurately capture the essence of the problem to be solved, avoiding any inconsistencies with the real world through the introduction of the simplifying assumptions. Unfortunately, analytical models aiming to describe the rupture of magma chamber walls are not entirely self consistent because so far they present a mixture of depth-dependent conditions with depth-independent assumptions, or rely on assumptions that neglect the material properties of real rocks. The most common assumptions include 1) The state of the system just before the onset of the rupture is such that the pressure inside the magma reservoir equals the pressure in the outside for the whole extension of the chamber, 2) Any increment in the internal pressure induces an equal increment in the stress experienced by the rock surrounding the chamber, 3) The confining pressure is lithostatic (i.e., a scalar), and 4) The material surrounding the chamber is isotropic. All of these four assumptions are inconsistent with the physical properties of the materials involved in situations relevant for the volcanic scenario or with the tensor-like nature of stress, therefore being somewhat misleading. For that reason, in this work it is developed a model of a magma reservoir that includes the response of real materials and that is entirely consistent with the principles of elastic linear theory. In particular, the lithostatic load is not longer considered a scalar quantity, and the cavity-related stress system is envisaged as related to a "center of compression" that bears some independence from the lithostatic stress-system As a result, the physical relevance of the analytical model is strengthened, avoiding the common flaws shared by previous formulations. Consequently, benchmark estimations of the amount of stress required to initiate the rupture of the walls of magma chambers can be established more confidently than until now through the relationship ?tang = Pvert sin2 ? + Phor cos2 ? - 1/2 (Pch a3) / R3 - 1/2 ?magma a (1- cos ?). It will also be shown that the influence of a free surface, of the magmastatic pressure inside the chamber, and of tectonic stresses, can be accounted for in a self-consistent form.

Canon-Tapia, E.

2011-12-01

421

Mathematical models and simulations of bacterial growth and chemotaxis in a diffusion gradient chamber.  

PubMed

The diffusion gradient chamber (DGC) is a novel device developed to study the response of chemotactic bacteria to combinations of nutrients and attractants [7]. Its purpose is to characterize genetic variants that occur in many biological experiments. In this paper, a mathematical model which describes the spatial distribution of a bacterial population within the DGC is developed. Mathematical analysis of the model concerning positivity and boundedness of the solutions are given. An ADI (Alternating Direction Implicit) method is constructed for finding numerical solutions of the model and carrying out computer simulations. The numerical results of the model successfully reproduced the patterns that were observed in the experiments using the DGC. PMID:11261315

Chiu, C; Hoppensteadt, F C

2001-02-01

422

Flow chamber  

SciTech Connect

A flow chamber having a vacuum chamber and a specimen chamber. The specimen chamber may have an opening through which a fluid may be introduced and an opening through which the fluid may exit. The vacuum chamber may have an opening through which contents of the vacuum chamber may be evacuated. A portion of the flow chamber may be flexible, and a vacuum may be used to hold the components of the flow chamber together.

Morozov, Victor (Manassas, VA)

2011-01-18

423

Modeling the combustion of JA2 and solid propellants of similar composition  

Microsoft Academic Search

A theoretical study on combustion of JA2, RPD-380, and RPD-351, which are modified double-base propellants composed primarily of three identical nitrate ester ingredients, is presented. A one-dimensional, two-phase model was used [M.S. Miller, W.R. Anderson, in: V. Yang, T.B. Brill, W.Z. Ren (Eds.), Solid Propellant Combustion Chemistry, Combustion and Motor Interior Ballistics, Progress in Astronautics and Aeronautics, vol. 185, AIAA,

Clint B. Conner; William R. Anderson

2009-01-01

424

Spatial Analysis of Emissions Sources for HCCI Combustion at Low Loads Using a Multi-Zone Model  

SciTech Connect

We have conducted a detailed numerical analysis of HCCI engine operation at low loads to investigate the sources of HC and CO emissions and the associated combustion inefficiencies. Engine performance and emissions are evaluated as fueling is reduced from typical HCCI conditions, with an equivalence ratio f = 0.26 to very low loads (f = 0.04). Calculations are conducted using a segregated multi-zone methodology and a detailed chemical kinetic mechanism for iso-octane with 859 chemical species. The computational results agree very well with recent experimental results. Pressure traces, heat release rates, burn duration, combustion efficiency and emissions of hydrocarbon, oxygenated hydrocarbon, and carbon monoxide are generally well predicted for the whole range of equivalence ratios. The computational model also shows where the pollutants originate within the combustion chamber, thereby explaining the changes in the HC and CO emissions as a function of equivalence ratio. The results of this paper contribute to the understanding of the high emission behavior of HCCI engines at low equivalence ratios and are important for characterizing this previously little explored, yet important range of operation.

Aceves, S M; Flowers, D L; Espinosa-Loza, F; Martinez-Frias, J; Dec, J E; Sjoberg, M; Dibble, R W; Hessel, R P

2004-02-20

425

STRUCTURE-BASED PREDICTIVE MODEL FOR COAL CHAR COMBUSTION  

SciTech Connect

This report is part on the ongoing effort at Brown University and Ohio State University to develop structure based models of coal combustion. A very fundamental approach is taken to the description of coal chars and their reaction processes, and the results are therefore expected to have broad applicability to the spectrum of carbon materials of interest in energy technologies. This quarter, our work on structure development in carbons continued. A combination of hot stage in situ and ex situ polarized light microscopy was used to identify the preferred orientational of graphene layers at gas interfaces in pitches used as carbon material precursors. The experiments show that edge-on orientation is the equilibrium state of the gas/pitch interface, implying that basal-rich surfaces have higher free energies than edge-rich surfaces in pitch. This result is in agreement with previous molecular modeling studies and TEM observations in the early stages of carbonization. The results may have important implications for the design of tailored carbons with edge-rich or basal-rich surfaces. In the computational chemistry task, we have continued our investigations into the reactivity of large aromatic rings. The role of H-atom abstraction as well as radical addition to monocyclic aromatic rings has been examined, and a manuscript is currently being revised after peer review. We have also shown that OH radical is more effective than H atom in the radical addition process with monocyclic rings. We have extended this analysis to H-atom and OH-radical addition to phenanthrene. Work on combustion kinetics focused on the theoretical analysis of the data previously gathered using thermogravametric analysis.

Robert H. Hurt; Eric M. Suuberg

2000-05-03

426

Structure-Based Predictive model for Coal Char Combustion.  

SciTech Connect

During the second quarter of this project, progress was made on both major technical tasks. Three parallel efforts were initiated on the modeling of carbon structural evolution. Structural ordering during carbonization was studied by a numerical simulation scheme proposed by Alan Kerstein involving molecular weight growth and rotational mobility. Work was also initiated to adapt a model of carbonaceous mesophase formation, originally developed under parallel NSF funding, to the prediction of coke texture. This latter work makes use of the FG-DVC model of coal pyrolysis developed by Advanced Fuel Research to specify the pool of aromatic clusters that participate in the order/disorder transition. Boston University has initiated molecular dynamics simulations of carbonization processes and Ohio State has begun theoretical treatment of surface reactions. Experimental work has also begun on model compound studies at Brown and on pilot-scale combustion systems with widely varying flame types at OSE. The work on mobility / growth models shows great promise and is discussed in detail in the body of the report.

Hurt, R.; Calo, J. [Brown Univ., Providence, RI (United States). Div. of Engineering; Essenhigh, R.; Hadad, C. [Ohio State Univ., Columbus, OH (United States). Dept. of Chemistry; Stanley, E. [Boston Univ., MA (United States). Dept. of Physics

1997-06-25

427

Supersonic flow structure in the entrance part of a mixing chamber of 2D model ejector  

Microsoft Academic Search

The paper deals with experimental and numerical results of investigation into supersonic and transonic flow past a two-dimensional\\u000a model ejector. Results of optical measurements show a flow structure and flow parameter development in the entrance part of\\u000a the mixing chamber of the ejector. Numerical results are obtained by means of both the straight solution of shock waves in\\u000a supersonic flow

Vaclav Dvorak; Pavel Safarik

2003-01-01

428

New formation of periodontal tissues around titanium implants in a novel dentin chamber model.  

PubMed

Direct bone-to-implant contact, defined as "osseointegration", is considered most optimal for long-term stability and survival of dental implants. However, the possibility of the formation of a tooth-like attachment apparatus around implants has also been demonstrated. The purpose of this study was to explore the formation of periodontal tissues around titanium implants using a novel and unique experimental model. After resection of the crowns of the maxillary canine teeth in nine mongrel dogs, the roots were hollowed to a depth of 5 mm leaving a thin dentinal wall. Slits were prepared in the cavity wall to create passages from the chamber to the periodontal ligament area. A custom-made, titanium implant was placed into the center of each chamber. Machined, titanium plasma sprayed (TPS) and sand blasted with large grit and acid attacked (SLA) surfaces were used. A collagen barrier was placed over the submerged chamber. Following 4 months of healing, jaw sections were processed for histology. Newly formed periodontal ligament, alveolar bone, and root cementum filled the space between the implant and the wall of the chamber. Ingrown bone was neither in contact with dentin nor with the implant. Thus, an interposed soft connective tissue layer was present. Healing by fibrous encapsulation was observed around most implants. However, cellular cementum was deposited on one TPS and one SLA implant and on the dentinal walls of the chamber. This study shows a remarkable capacity for new periodontal tissue formation at a site where no such tissues ever existed. Maintenance of original periodontal tissue domains most likely prevented osseointegration of the implants. The cementum layer deposited on two implants was likely formed through cementoconductivity rather than by differentiation of periodontal ligament cells upon contact with the implant surface. PMID:15877745

Parlar, Ates; Bosshardt, Dieter D; Unsal, Berrin; Cetiner, Deniz; Haytaç, Cenk; Lang, Niklaus P

2005-06-01

429

Active ellipse model and automatic chamber detection in apical views of echocardiography images.  

PubMed

In this article, an automatic method for detection of all chambers in apical two- and four-chamber views is proposed. The method is based on four evolving ellipses with their sizes and alignments (centre point) gradually changing through iterations until they reach to the point that approximates the chamber boundaries. The interaction between the internal, external and inter-elliptic forces controls the simultaneous evolution of ellipses. Since no prior assumption of the approximate location is required with our approach, the specialists are not required to locate the centre points of chambers in apical images, making the overall segmentation fully automated. Moreover, the resultant ellipse inside a chamber could be used as the initial contour in segmentation techniques such as active contour models, where the initial contour has a significant role for higher accuracy and faster convergence. The simplicity of equations developed in our approach make for a computationally faster algorithm, compared with former approaches that utilize morphologic operators. Our evolving ellipse does not go beyond the gaps, a problem that normally exists within boundaries in echo images, making our overall segmentation process more robust against the gaps. To evaluate the proposed method, a subset of 80 images is selected and three observers are requested to manually draw best ellipses inside the images and compare them with our results. The obtained dice coefficient results (87.62 ± 4.53% for observer-1, 83.18 ± 6.20% for observer-2, 86.02 ± 5.16% for observer-3) indicate that the proposed method has a useful performance. PMID:22033131

Marsousi, Mahdi; Ahmadian, Alireza; Kocharian, Armen; Alirezaie, Javad

2011-10-26

430

Volcanoes Behave as Composite Materials: Implications for Modeling Magma Chambers, Dikes, and Surface Deformation  

NASA Astrophysics Data System (ADS)

By definition, composite volcanoes are composed of numerous alternating material units or layers such as lavas, sediments, and pyroclastics. Commonly, these layers have widely different mechanical properties. In particular, some lava flows and welded pyroclastic flows may be stiff (with a high Young's modulus), whereas others, such as non-welded pyroclastic units and sediments, may be soft (with a low Young's modulus). As a consequence, even if the loading (tectonic stress, magmatic pressure, or displacement) is uniform, the stresses within the composite volcano will vary widely. In this sense, the behavior of composite volcanoes is similar to that of general composite materials. The deformation of the surface of a volcano during an unrest period results from stresses generated by processes and parameters such as fluid pressure in a geothermal field or a magma chamber, a regional tectonic event, and a dike injection. Here we present new numerical models on mechanics of magma chambers and dikes, and the associated surface deformation of composite volcanoes. The models show that the surface deformation during magma-chamber inflation and deflation depends much on the chamber geometry, the loading conditions, and the mechanical properties of the rock units that constitute the volcano. The models also indicate that the surface deformation induced by a propagating dike depends much on the mechanical properties of the layers between the dike tip and the surface. In particular, the numerical results show that soft layers and weak contacts between layers may suppress the dike-induced tensile stresses and the associated surface deformation. Many dikes may therefore become injected and arrested at shallow depths in a volcano while giving rise to little or no surface deformation. Traditional analytical surface-deformation models such as a point source (Mogi model) for a magma-chamber pressure change and a dislocation for a dike normally assume the volcano to behave as a homogeneous, isotropic half space. The present numerical results, combined with field studies, indicate that such analytical models may yield results that have little similarity with the actual structure being modeled.

Leiss, B.; Gudmundsson, A.; Philipp, S. L.

2005-12-01

431

Computation of turbulent flow in a cyclone chamber with a Reynolds stress turbulence model  

NASA Astrophysics Data System (ADS)

The cyclone separator is widely used as a means of dust removal from gases in industrial applications. In this chamber, there formed a very complex flow field, involving the interaction between the highly swirling velocity and the turbulent stress field. The problem of predicting this kind of flows is solved by applying a Reynolds stress transport model. Further, a calculation with a k-epsilon model is performed in order to compare the predicting performance. It is shown that the predicted results obtained by the Reynolds stress model are in good agreement with those of measurements.

Kitamura, Osamu; Yamamoto, Makoto; Arakawa, Chuichi; Kawata, Yutaka

1992-12-01

432

On precisely modelling surface deformation due to interacting magma chambers and dykes  

NASA Astrophysics Data System (ADS)

Combined data sets of InSAR and GPS allow us to observe surface deformation in volcanic settings. However, at the vast majority of volcanoes, a detailed 3-D structure that could guide the modelling of deformation sources is not available, due to the lack of tomography studies, for example. Therefore, volcano ground deformation due to magma movement in the subsurface is commonly modelled using simple point (Mogi) or dislocation (Okada) sources, embedded in a homogeneous, isotropic and elastic half-space. When data sets are too complex to be explained by a single deformation source, the magmatic system is often represented by a combination of these sources and their displacements fields are simply summed. By doing so, the assumption of homogeneity in the half-space is violated and the resulting interaction between sources is neglected. We have quantified the errors of such a simplification and investigated the limits in which the combination of analytical sources is justified. We have calculated the vertical and horizontal displacements for analytical models with adjacent deformation sources and have tested them against the solutions of corresponding 3-D finite element models, which account for the interaction between sources. We have tested various double-source configurations with either two spherical sources representing magma chambers, or a magma chamber and an adjacent dyke, modelled by a rectangular tensile dislocation or pressurized crack. For a tensile Okada source (representing an opening dyke) aligned or superposed to a Mogi source (magma chamber), we find the discrepancies with the numerical models to be insignificant (<5 per cent) independently of the source separation. However, if a Mogi source is placed side by side to an Okada source (in the strike-perpendicular direction), we find the discrepancies to become significant for a source separation less than four times the radius of the magma chamber. For horizontally or vertically aligned pressurized sources, the discrepancies are up to 20 per cent, which translates into surprisingly large errors when inverting deformation data for source parameters such as depth and volume change. Beyond 8 radii however, we demonstrate that the summation of analytical sources represents adjacent magma chambers correctly.

Pascal, Karen; Neuberg, Jurgen; Rivalta, Eleonora

2013-10-01

433

Characterization of complexities in combustion instability in a lean premixed gas-turbine model combustor.  

PubMed

We characterize complexities in combustion instability in a lean premixed gas-turbine model combustor by nonlinear time series analysis to evaluate permutation entropy, fractal dimensions, and short-term predictability. The dynamic behavior in combustion instability near lean blowout exhibits a self-affine structure and is ascribed to fractional Brownian motion. It undergoes chaos by the onset of combustion oscillations with slow amplitude modulation. Our results indicate that nonlinear time series analysis is capable of characterizing complexities in combustion instability close to lean blowout. PMID:23278063

Gotoda, Hiroshi; Amano, Masahito; Miyano, Takaya; Ikawa, Takuya; Maki, Koshiro; Tachibana, Shigeru

2012-12-01

434

Coherent Flame Model of Premixed Turbulent Combustion in a Counterflow Geometry.  

National Technical Information Service (NTIS)

Premixed combustion in turbulent counterflowing streams is studied theoretically by adopting a coherent flame model. With this model, a flame surface density Sigma-bar, described by a transport equation, is used to calculate the mean chemical reaction rat...

A. S. Wu K. N. C. Bray

1993-01-01

435

Pulverized straw combustion in a low-NO x multifuel burner: Modeling the transition from coal to straw  

Microsoft Academic Search

A CFD simulation of pulverized coal and straw combustion using a commercial multifuel burner have been undertaken to examine the difference in combustion characteristics. Focus has also been directed to development of the modeling technique to deal with larger non-spherical straw particles and to determine the relative importance of different modeling choices for straw combustion. Investigated modeling choices encompass the

M. Mandø; L. Rosendahl; C. Yin; H. Sørensen

2010-01-01

436

Engine combustion control responsive to location and magnitude of peak combustion pressure  

SciTech Connect

A combustion control is described for an internal combustion engine of the type having combustion chambers, means for supplying a combustible charge to and igniting the combustible charge within each combustion chamber, power output apparatus including a rotating crankshaft, and means for sensing the crankshaft angle (LPP) and magnitude (MPP) of peak combustion pressure for each combustion chamber. The combustion control consists of: means for deriving the average magnitude of peak combustion pressure (AMPP); means for determining base values; memory means for storing tables of LPP ignition trim values, MPP ignition trim values and A/F trim values for each combustion chamber; means for comparing the sensed LPP value for each combustion chamber with a desired LPP value (DLPP) for that combustion chamber and adjusting the LPP ignition trim value for the predetermined engine operating parameters; means for comparing the MPP value for each combustion chamber with the average magnitude of peak combustion pressure; means to adjust the A/F trim value in the rich direction and reset the MPP ignition trim value; means to adjust the MPP ignition trim value in the advance direction; means to adjust the A/F trim value in the lean direction and reset the MPP ignition trim value; means for determining the combustible charge mixture for each combustion chamber from the base value thereof and the A/F trim value for the sensed predetermined engine operating parameters; means for determining the ignition timing for each combustion.

Tombley, D.E.

1987-11-17

437

Thermodynamic Model of Aluminum Combustion in SDF Explosions  

Microsoft Academic Search

Thermodynamic states encountered during combustion of Aluminum powder in Shock-Dispersed-Fuel (SDF) explosions were analyzed with the Cheetah code. Results are displayed in the Le Chatelier diagram: the locus of states of specific internal energy versus temperature. Accuracy of the results was confirmed by comparing the fuel and products curves with the heats of detonation and combustion, and species composition as

Kuhl

2006-01-01

438

Heat release model for the combustion of diesel oil emulsions in DI diesel engines  

Microsoft Academic Search

Diagnosing the combustion process in internal combustion engines using cylinder pressure, fuel delivery pressure and injector needle lift data is a well-established and widely used procedure in engine and fuel performance tests. Of the models developed, the first law single zone is the simplest and easiest tool to use for quick preliminary analysis of engine performance. It can yield valuable

Jamil Ghojel; Damon Honnery

2005-01-01

439

Transient experiments and modeling of the catalytic combustion of methane in a monolith reactor  

Microsoft Academic Search

The combustion of methane with an excess of oxygen was examined under transient conditions in a catalytic monolith reactor. The reaction exhibited a sharp light off in the inlet region of the reactor, and essentially complete combustion was attained. The experimental reactor was modeled using a comprehensive two-dimensional finite element simulator previously developed. Theoretical and observed temperatures were well matched

Robert E. Hayes; Stan T. Kolaczkowski; W. John Thomas; James Titiloye

1996-01-01

440

An analytical and numerical model of radiation heat transfer in direct injection-type diesel combustion  

Microsoft Academic Search

The research has been directed to a better understanding of the processes of particulate formation and radiation that transfer in direct injection type diesel engine combustion. The dissertation considers an analytical and numerical model of radiation heat transfer in a combustion reactor containing soot laden flames as an immediate application to the direct injection type diesel engine. The governing equation

S. L. Chang

1984-01-01

441

DEVELOPMENT OF THE INDUSTRIAL COMBUSTION EMISSIONS MODEL FOR ACID RAIN ANALYSES  

EPA Science Inventory

The paper discusses forecasts of industrial combustion emissions being developed by the U.S. EPA as part of the National Acid Precipitation Assessment Program (NAPAP). The Industrial Combustion Emissions (ICE) Model will estimate sulfur dioxide (SO2), nitrogen oxides (NOx), and p...

442

Modelling for the optimization of the reaction chamber in silicon nanoparticle synthesis by a radio-frequency induction thermal plasma  

NASA Astrophysics Data System (ADS)

The optimization of the reaction chamber for the silicon nanoparticle synthesis process by a radio-frequency induction thermal plasma is addressed using a plasma thermo-fluid-dynamic model coupled with electromagnetic field equations and with a moment model for nanoparticle transport. Various reaction chamber geometries composed of two parts—a conical top and a cylindrical bottom—are evaluated in terms of the yield of the synthesis process, the presence of recirculation flow patterns that may affect the uniformity of the produced nanoparticles and the size distribution of nanoparticles at the chamber outlet. Turbulent diffusion is suggested as the physical phenomenon that leads to nanoparticle deposition onto the walls of the reaction chamber. The injection of a suitable gas along the walls of the reaction chamber at the axial position, where the nanoparticle nucleation takes place, is proven to be effective in increasing the synthesis process yield.

Colombo, V.; Ghedini, E.; Gherardi, M.; Sanibondi, P.

2012-10-01

443

Externally ignited internal combustion engine  

SciTech Connect

An internal combustion engine in which each cylinder or combustion volume includes a separate ignition chamber which communicates with the main combustion chamber through a relatively narrow channel or channels is described. The combustible mixture is delivered to the separate chamber exclusively through these channels by the compressive action of the piston and is ignited there by a suitable electrical spark, for example. There is no additional admission of fuel or fuel mixture to the separate ignition chamber. The channel or channels terminate in the ignition chamber in such a manner, for example, tangentially, that one or more vortices are generated in the chamber prior to ignition. The channels are so oriented that the emerging igniter flames are directed to potential hot cells in the main combustion chamber where auto-ignition could occur.

Latsch, R.; Schlembach, H.

1980-08-26

444

STRUCTURE-BASED PREDICTIVE MODEL FOR COAL CHAR COMBUSTION  

SciTech Connect

During the past quarter of this project, significant progress continued was made on both major technical tasks. Progress was made at OSU on advancing the application of computational chemistry to oxidative attack on model polyaromatic hydrocarbons (PAHs) and graphitic structures. This work is directed at the application of quantitative ab initio molecular orbital theory to address the decomposition products and mechanisms of coal char reactivity. Previously, it was shown that the ?hybrid? B3LYP method can be used to provide quantitative information concerning the stability of the corresponding radicals that arise by hydrogen atom abstraction from monocyclic aromatic rings. In the most recent quarter, these approaches have been extended to larger carbocyclic ring systems, such as coronene, in order to compare the properties of a large carbonaceous PAH to that of the smaller, monocyclic aromatic systems. It was concluded that, at least for bond dissociation energy considerations, the properties of the large PAHs can be modeled reasonably well by smaller systems. In addition to the preceding work, investigations were initiated on the interaction of selected radicals in the ?radical pool? with the different types of aromatic structures. In particular, the different pathways for addition vs. abstraction to benzene and furan by H and OH radicals were examined. Thus far, the addition channel appears to be significantly favored over abstraction on both kinetic and thermochemical grounds. Experimental work at Brown University in support of the development of predictive structural models of coal char combustion was focused on elucidating the role of coal mineral matter impurities on reactivity. An ?inverse? approach was used where a carbon material was doped with coal mineral matter. The carbon material was derived from a high carbon content fly ash (Fly Ash 23 from the Salem Basin Power Plant. The ash was obtained from Pittsburgh #8 coal (PSOC 1451). Doped samples were then burned in a high temperature flame reactor fitted with rapid quench extractive sampling. It was found that the specific reaction rate decreased with increasing ash content by about an order of magnitude over the ash content range investigated. In this case, it was concluded that at least one of the primary reasons for the resultant observation was that an increasing amount of carbon becomes inaccessible to oxygen by being covered with a fused, ?protective,? ash layer. Progress continued on equipment modification and testing for the combustion experiments with widely varying flame types at OSU.

CHRISTOPHER M. HADAD; JOSEPH M. CALO; ROBERT H. ESSENHIGH; ROBERT H. HURT

1998-06-04

445

Computational Combustion  

SciTech Connect

Progress in the field of computational combustion over the past 50 years is reviewed. Particular attention is given to those classes of models that are common to most system modeling efforts, including fluid dynamics, chemical kinetics, liquid sprays, and turbulent flame models. The developments in combustion modeling are placed into the time-dependent context of the accompanying exponential growth in computer capabilities and Moore's Law. Superimposed on this steady growth, the occasional sudden advances in modeling capabilities are identified and their impacts are discussed. Integration of submodels into system models for spark ignition, diesel and homogeneous charge, compression ignition engines, surface and catalytic combustion, pulse combustion, and detonations are described. Finally, the current state of combustion modeling is illustrated by descriptions of a very large jet lifted 3D turbulent hydrogen flame with direct numerical simulation and 3D large eddy simulations of practical gas burner combustion devices.

Westbrook, C K; Mizobuchi, Y; Poinsot, T J; Smith, P J; Warnatz, J

2004-08-26

446

Barriers to transport induced by periodic oscillations in a physical model of the human vitreous chamber  

NASA Astrophysics Data System (ADS)

Understanding mixing processes that occur in the human vitreous chamber is of fundamental importance due to the relevant clinical implications in drug delivery treatments of several eye conditions. In this article we rely on experimental observations (which demonstrated that dispersion coefficients largely dominate diffusive coefficients) on a physical model of the human eye to perform an analysis based on Lagrangian trajectories. In particular, we study barriers to transport in a particularly significant two-dimensional section of the eye model by using nonlinear dynamical systems theoretical and numerical tools. Bifurcations in the system dynamics are investigated by varying the main physical parameters of the problem.

Oliveri, Alberto; Stocchino, Alessandro; Storace, Marco

2011-03-01

447

Solid waste combustion for alpha waste incineration  

SciTech Connect

Radioactive waste incinerator development at the Savannah River Laboratory has been augmented by fundamental combustion studies at the University of South Carolina. The objective was to measure and model pyrolysis and combustion rates of typical Savannah River Plant waste materials as a function of incinerator operating conditions. The analytical models developed in this work have been incorporated into a waste burning transient code. The code predicts maximum air requirement and heat energy release as a function of waste type, package size, combustion chamber size, and temperature. Historically, relationships have been determined by direct experiments that did not allow an engineering basis for predicting combustion rates in untested incinerators. The computed combustion rates and burning times agree with measured values in the Savannah River Laboratory pilot (1 lb/hr) and full-scale (12 lb/hr) alpha incinerators for a wide variety of typical waste materials.

Orloff, D.I.

1981-02-01

448

Extinction of model fuels with anomalous pressure dependence of the combustion velocity  

SciTech Connect

This article investigates the regimes of combustion of model fuels with a drop in pressure. The following fuel compositions were examined: a reference composition consisting of a model nitroglycerine fuel, nitroglycerine fuel with a 2% additive of lead and copper compounds, and nitroglycerine with the addition of 1% compound of lead. The temperature gradient in the gas near the combustion surface was determined from the temperature profile. The results indicate that when the pressure boundary for the change in combustion mechanisms is crossed during the pressure drop, the conditions for extinguishing the fuel are considerably eased. It is concluded that the investigation of fuel combustion accompanying a pressure drop permits the obtaining of additional data and enables the understanding of the combustion mechanism at constant pressure.

Marshakov, V.N.; Melik-Gaikazov, G.V.

1983-09-01

449

Mathematical modeling and analysis of the flocculation process in chambers in series.  

PubMed

In this study, the flocculation process in continuous systems with chambers in series was analyzed using the classical kinetic model of aggregation and break-up proposed by Argaman and Kaufman, which incorporates two main parameters: K a and K b. Typical values for these parameters were used, i. e., K a = 3.68 × 10(-5)-1.83 × 10(-4) and K b = 1.83 × 10(-7)-2.30 × 10(-7) s(-1). The analysis consisted of performing simulations of system behavior under different operating conditions, including variations in the number of chambers used and the utilization of fixed or scaled velocity gradients in the units. The response variable analyzed in all simulations was the total retention time necessary to achieve a given flocculation efficiency, which was determined by means of conventional solution methods of nonlinear algebraic equations, corresponding to the material balances on the system. Values for the number of chambers ranging from 1 to 5, velocity gradients of 20-60 s(-1) and flocculation efficiencies of 50-90 % were adopted. PMID:22890412

Moruzzi, Rodrigo Braga; de Oliveira, Samuel Conceição

2012-08-14

450

Experimental and kinetic modeling study of the combustion of Jet-A and S-8 fuels in laminar premixed flames  

Microsoft Academic Search

Laminar flame speeds and Markstein lengths of Jet-A\\/air, and S-8\\/air flames at an elevated initial temperature and various initial pressures were measured using spherically expanding premixed flames. The experimental facility has been developed to study the combustion behaviors of high-boiling-point and low-vapor-pressure liquid fuels. The experiment used a spherical combustion chamber housed inside a customized oven, which provides a uniform

Takayuki Nishiie

2010-01-01

451

Multiphase CFD-based models for chemical looping combustion process: Fuel reactor modeling  

SciTech Connect

Chemical looping combustion (CLC) is a flameless two-step fuel combustion that produces a pure CO2 stream, ready for compression and sequestration. The process is composed of two interconnected fluidized bed reactors. The air reactor which is a conventional circulating fluidized bed and the fuel reactor which is a bubbling fluidized bed. The basic principle is to avoid the direct contact of air and fuel during the combustion by introducing a highly-reactive metal particle, referred to as oxygen carrier, to transport oxygen from the air to the fuel. In the process, the products from combustion are kept separated from the rest of the flue gases namely nitrogen and excess oxygen. This process eliminates the energy intensive step to separate the CO2 from nitrogen-rich flue gas that reduce the thermal efficiency. Fundamental knowledge of multiphase reactive fluid dynamic behavior of the gas–solid flow is essential for the optimization and operation of a chemical looping combustor. Our recent thorough literature review shows that multiphase CFD-based models have not been adapted to chemical looping combustion processes in the open literature. In this study, we have developed the reaction kinetics model of the fuel reactor and implemented the kinetic model into a multiphase hydrodynamic model, MFIX, developed earlier at the National Energy Technology Laboratory. Simulated fuel reactor flows revealed high weight fraction of unburned methane fuel in the flue gas along with CO2 and H2O. This behavior implies high fuel loss at the exit of the reactor and indicates the necessity to increase the residence time, say by decreasing the fuel flow rate, or to recirculate the unburned methane after condensing and removing CO2.

Jung, Jonghwun (ANL); Gamwo, I.K.

2008-04-21

452

Modeling of internal combustion engine based cogeneration systems for residential applications  

Microsoft Academic Search

A parametric model that can be used in the design and techno-economic evaluation of internal combustion engine (ICE) based cogeneration systems for residential use is presented. The model, which is suitable to be incorporated into a building simulation program, includes sub-models for internal combustion engines and generators, electrical\\/thermal storage systems, and secondary system components (e.g. controllers), and is capable of

Hycienth I. Onovwiona; V. Ismet Ugursal; Alan S. Fung

2007-01-01

453

Multiphase modeling study for storm water solids treatment in experimental storm water settling chamber.  

PubMed

This study tests four different types of multiphase models to determine the most appropriate model for predicting the behaviors of various types of storm water solids in a settling chamber. The Lagrangian reference frame discrete phase models of uncoupled and coupled models based on the interaction between the discrete phase and the continuous phase were tested. The rigid moving objects model providing six degrees of freedom particle motion was also tested to model non-spherical particle motion. The fourth model was a sediment transport model using the Eulerian reference frame model. This study tested five different storm water solids consisting of bulk, gross, coarse, sediment and fine which are classified by particle size and settling characteristics. Particle settling efficiency and computational time were considered in determining the most appropriate multiphase model. The coupled model provided better solid settling than the uncoupled model, but required 8.2% more computational time in this study. The Eulerian model matched settling efficiency for the high density finer solids. Although the Eulerian model showed reliable settling prediction, the Lagrangian coupled model can be an effective alternative requiring significantly reduced computational time. PMID:22049733

Ho, Jungseok

2011-01-01

454

Evaluation of char combustion models: measurement and analysis of variability in char particle size and density  

SciTech Connect

Char samples representing a range of combustion conditions and extents of burnout were obtained from a well-characterized laminar flow combustion experiment. Individual particles from the parent coal and char samples were characterized to determine distributions in particle volume, mass, and density at different extent of burnout. The data were then compared with predictions from a comprehensive char combustion model referred to as the char burnout kinetics model (CBK). The data clearly reflect the particle- to-particle heterogeneity of the parent coal and show a significant broadening in the size and density distributions of the chars resulting from both devolatilization and combustion. Data for chars prepared in a lower oxygen content environment (6% oxygen by vol.) are consistent with zone II type combustion behavior where most of the combustion is occurring near the particle surface. At higher oxygen contents (12% by vol.), the data show indications of more burning occurring in the particle interior. The CBK model does a good job of predicting the general nature of the development of size and density distributions during burning but the input distribution of particle size and density is critical to obtaining good predictions. A significant reduction in particle size was observed to occur as a result of devolatilization. For comprehensive combustion models to provide accurate predictions, this size reduction phenomenon needs to be included in devolatilization models so that representative char distributions are carried through the calculations.

Daniel J. Maloney; Esmail R. Monazam; Kent H. Casleton; Christopher R. Shaddix

2008-08-01

455

A Kinetic Model of Carbon Burnout in Pulverized Coal Combustion  

Microsoft Academic Search

The degree of carbon burnout is an important operating characteristic of full-scale suspension-fired coal combustion systems. Prediction of carbon loss requires special char combustion kinetics valid through the very high conversions targeted in industry (typically >99.5%), and valid for a wide range of particle temperature histories occurring in full-scale furnaces. The present paper presents high-temperature kinetic data for five coal

Robert Hurt; Jian-Kuan Sun; Melissa Lunden

1998-01-01

456

Ignition system and method for multi-fuel combustion engines  

Microsoft Academic Search

A method for combusting fuel in the combustion chamber of a multi-fuel internal combustion engine by both spark ignition and hot surface ignition, is described comprising the steps of: retaining combustion heat in an electrode apparatus positioned in the combustion chamber for providing surface ignition of the fuel when the electrode apparatus has reached a sufficient temperature, the electrode apparatus

J. A. Lo Russo; H. A. Cikanek; R. W. Anderson

1988-01-01

457

Development of a Practical Soot Modeling Approach and Its Application to Low-Temperature Diesel Combustion  

Microsoft Academic Search

The author's developed a practical soot model and implemented in the multidimensional computational fluid dynamics code, KIVA-3vr2 for use in low temperature diesel combustion simulations. The model framework is based on four fundamental steps: soot inception through a four-ring polycyclic aromatic hydrocarbon species, surface growth through acetylene, soot coagulation, and oxygen- and OH-induced soot oxidation. Diesel combustion was simulated by

Gokul Vishwanathan; Rolf D. Reitz

2010-01-01

458

Modelling Of Hindered Crystal Settling-Floating Process In A Magma Chamber  

NASA Astrophysics Data System (ADS)

In interior of magma chamber during the fractional crystallisation, the separation of the minerals can be done by a simple density contrast. The denser minerals sank to the bottom of magma chamber and can formed, later, a cumulate layer. In order to better understand the relations between cumulus texture and evolution of the chemical composition at grain boundaries during the crystal-melt settling-floating process, a series of centrifuge experiments have been carried out. The experiments were conducted in a centrifuging furnace at 1235°C under atmospheric pressure during 6 hours and with an acceleration range between 1g to 1000g of partially molten gabbro samples with the grain size 100?m. Crystals during the centrifuging process have been segregated according to their buoyancy: plagioclase crystals floated to the top and magnetite crystals sank to the bottom of container. The chemical evolution of melt, vertical and horizontal distribution of crystals and melt in the experiments at 100g and 200g is similar. The segregation realized in experiments at 500g and 1000g revealed much worse separation of heavy and light crystals and the melt phase. The vertical evolution of the major and trace elements in the melt phase shows that close to the cumulate layer (between 0 to 2 mm from the bottom) the variation of these elements depends on the distance from the container wall, and becomes constant in the interior of sample. The horizontal evolution shows some variations which appear close to the walls of the capsule and which are due to the wall effect during the centrifuging runs. In order to describe the compaction evolution with time, a numerical modelling of the sedimentation process of the crystals has been build and then compared with the centrifuge modelling. The numerical and centrifuge modelling results agree quite well: the stratification of the compacted layer in the runs is reproduced in numerical models. The settling model of a concentrated suspension can predict a realistic evolution of the cumulus layer compaction for a time scale of several years. The combination of centrifuge experiments and numerical modelling demonstrates that in magma chambers there are correlations between cumulus textures and the evolution of chemical composition at grain boundaries during the stage when crystals come into mechanical contact with each other in a cumulus layer. Finally, formation time and melt fraction evolution of Muskox layered intrusion have been revisited using the hindered sedimentation model calculations. The results on the time formation of the intrusion as well as the porosity loss with time are in agreement with previous results of the compaction model.

Berres, S.; Forien, M.; Bagdassarov, N. S.; Dingwell, D. B.

2011-12-01

459

Simplified Combustion Modeling of Double Base Propellant: Gas Phase Chain Reaction Vs. Thermal Decomposition  

Microsoft Academic Search

Simplified combustion modeling of nitrocellulose (NC), nitroglycerin (NG) double base propellant is considered. Two models with simple but rational chemistry are compared: the classical thermal decomposition, high gas activation energy (Eg\\/RT> > 1) Denison-Baum-Williams (DBW) model, and a new chain reaction, low gas activation energy (Eg\\/RT < < 1) model recently proposed by Ward, Son, and Brewster (WSB). Both models

M. Q. BREWSTER; M. J. WARD; S. F. SON

2000-01-01

460

Thermal ignition combustion system  

DOEpatents

The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m.degree. C. and a specific heat greater than 480 J/kg.degree. C. with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber.

Kamo, Roy (Columbus, IN); Kakwani, Ramesh M. (Columbus, IN); Valdmanis, Edgars (Columbus, IN); Woods, Melvins E. (Columbus, IN)

1988-01-01

461

Thermal ignition combustion system  

DOEpatents

The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

1988-04-19

462

HCCl Combustion: Analysis and Experiments  

SciTech Connect

Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work. On analysis, we have developed two powerful tools: a single zone model and a multi-zone model. The single zone model has proven very successful in predicting start of combustion and providing reasonable estimates for peak cylinder pressure, indicated efficiency and NOX emissions. This model is being applied to develop detailed engine performance maps and control strategies, and to analyze the problem of engine startability. The multi-zone model is capable of very accurate predictions of the combustion process, including HC and CO emissions. The multi-zone model has applicability to the optimization of combustion chamber geometry and operating conditions to achieve controlled combustion at high efficiency and low emissions. On experimental work, we have done a thorough evaluation of operating conditions in a 4-cylinder Volkswagen TDI engine. The engine has been operated over a wide range of conditions by adjusting the intake temperature and the fuel flow rate. Satisfactory operation has been obtained over a wide range of operating conditions. Cylinder-to-cylinder variations play an important role in limiting maximum power, and should be controlled to achieve satisfactory performance.

Aceves, S M; Flowers, D L; Martinez-Frias, J; Smith, J R; Dibble, R; Au, M; Girard, J

2001-05-04

463

DESCRIPTION OF THE INDUSTRIAL COMBUSTION EMISSIONS MODEL (VERSION 6.0)  

EPA Science Inventory

The report describes the model methodology, key assumptions, data sources, and user options for Version 6 of the Industrial Combustion Emissions (ICE) Model, one of a number of National Acid Precipitation Assessment Program emission forecasting models. Future ICE Model runs may i...

464

Energy dependence of correction factors for some Victoreen Model 570 Condensor R-Meter medium-energy chambers.  

PubMed

The energy dependence of each of six models of medium-energy Victoreen 570 Condenser R-Meter chambers was determined by measurement of the exposure correction factors over the diagnostic x-ray beam-quality range (0.4-4.1 mm A1 HVL) for several samples of each model. The results of an analysis of variance performed by model on the correction factors are reported as mean correction factors for the x-ray beams evaluated, with a relative standard error less than 0.8% in all cases. Energy-dependence curves for the six chamber models are given; their use is described. PMID:904597

Morgan, T J; Brateman, L; Dirkse, J

465

Modeling of nitrogen oxides formation and destruction in combustion systems  

Microsoft Academic Search

The formation of nitrogen oxides (NOX) in combustion systems is a significant pollutant source in the environment, and the control of NOX emissions is a world-wide concern as the utilization of fossil fuels continues to increase. In addition, the use of alternative fuels, which are typically of lower quality, tends to worsen the problem. Advances in the science of NOX

S. C Hill; L Douglas Smoot

2000-01-01

466

Nonlinear Model Predictive Control of Municipal Solid Waste Combustion Plants  

Microsoft Academic Search

Combustion of municipal solid waste (MSW; = household waste) is used to reduce its volume and to produce energy. It is performed in furnaces at large industrial plants for which the control problem is to maximize waste throughput and energy output while still fulfilling life time and environment re- lated constraints. This inevitably leads to a constraint pushing control problem

M. Leskens; R. J. P. van der Linden; L. B. M. van Kessel; O. H. Bosgra

2008-01-01

467

Modeling of combustion processes in a solid fuel particle  

Microsoft Academic Search

During the production of granules of uranium oxide, granules of ion exchange resin, loaded with uranium ions, are burned to remove the resin matrix and leave a uranium oxide ash''. Under some conditions of combustion, the oxide granules are produced in a