scholarly journals Traversing Hot-Jet Ignition in a Constant-Volume Combustor

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Abdullah Karimi ◽  
Manikanda Rajagopal ◽  
Razi Nalim
Keyword(s):  
High Speed ◽  
Internal Combustion Engines ◽  
Combustion Products ◽  
Combustible Mixture ◽  
Constant Volume ◽  
Atmospheric Conditions ◽  
Wave Rotor ◽  
Numerical Predictions ◽  
Stable Species ◽  
Hot Jet Ignition

Hot-jet ignition of a combustible mixture has application in internal combustion engines, detonation initiation, and wave rotor combustion. Numerical predictions are made for ignition of combustible mixtures using a traversing jet of chemically active gas at one end of a long constant-volume combustor (CVC) with an aspect ratio similar to a wave rotor channel. The CVC initially contains a stoichiometric mixture of ethylene or methane at atmospheric conditions. The traversing jet issues from a rotating prechamber that generates gaseous combustion products, assumed at chemical equilibrium for estimating major species. Turbulent combustion uses a hybrid eddy-breakup model with detailed finite-rate kinetics and a two-equation k-ω model. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure, and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Pressure waves in the CVC chamber affect ignition through flame vorticity generation and compression. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive.

scholarly journals Traversing Hot-Jet Ignition in a Constant-Volume Combustor

2013 ◽  
Author(s):  
Abdullah Karimi ◽  
Manikanda Rajagopal ◽  
Razi Nalim
Keyword(s):  
High Speed ◽  
Combustion Products ◽  
Combustible Mixture ◽  
Constant Volume ◽  
Atmospheric Conditions ◽  
Wave Rotor ◽  
Numerical Predictions ◽  
Stable Species ◽  
Hot Jet Ignition ◽  
Combustible Mixtures

Hot-jet ignition of a combustible mixture has application in IC engines, detonation initiation, and wave rotor combustion. Numerical predictions are made for ignition of combustible mixtures using a traversing jet of chemically active gas at one end of a long constant-volume combustor (CVC) with aspect ratio similar to a wave rotor channel. The CVC initially contains a stoichiometric mixture of ethylene or methane at atmospheric conditions. The traversing jet issues from a rotating pre-chamber that generates gaseous combustion products, assumed at chemical equilibrium for estimating major species. Turbulent combustion uses a hybrid eddy-break-up model with detailed finite-rate kinetics and a two-equation k-ω model. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Pressure waves in the CVC chamber affect ignition through flame vorticity generation and compression. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive.

scholarly journals Ignition by Hot Transient Jets in Confined Mixtures of Gaseous Fuels and Air

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Abdullah Karimi ◽  
M. Razi Nalim
Keyword(s):  
Reaction Mechanism ◽  
Reaction Rate ◽  
Numerical Study ◽  
Combustion Products ◽  
Combustible Mixture ◽  
Constant Volume ◽  
Initial Reaction ◽  
Ignition Process ◽  
Gaseous Fuels ◽  
Hot Jet Ignition

Ignition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, prechamber ignition in IC engines, detonation initiation, and novel constant-volume combustors. The present work is a numerical study of the hot jet ignition process in a long constant-volume combustor (CVC) that represents a wave rotor channel. The hot jet of combustion products from a prechamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using a global reaction mechanism, a skeletal mechanism, or a detailed reaction mechanism for three hydrocarbon fuels: methane, propane, and ethylene. Turbulence is modeled using the two-equation SSTk-ωmodel, and each reaction rate is limited by the local turbulent mixing timescale. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock wave traverse of the reaction zone is seen to significantly increase the overall reaction rate, likely due to compression heating, as well as baroclinic vorticity generation that stirs and mixes reactants and increases flame area. Less easily ignitable methane mixture is found to show slower initial reaction and greater dependence on shock interaction than propane and ethylene.

EMISSION OF POLYCYCLIC AROMATIC HYDROCARBONS CONTAINED IN COMBUSTION PRODUCTS OF GASOLINE ENGINES

2018 ◽  
Vol 62 (3) ◽  
pp. 341-346 ◽  
Author(s):  
M. Assad ◽  
V. V. Grushevski ◽  
O. G. Penyazkov ◽  
I. N. Tarasenko
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Catalytic Converter ◽  
Combustion Products ◽  
Chromatography Method ◽  
Exhaust Gases ◽  
Polycyclic Aromatic ◽  
Load Mode

The concentration of 16 polycyclic aromatic hydrocarbons (PAHs) in the gasoline combustion products emitted into the atmosphere by internal combustion engines (ICE) has been measured using the gas chromatography method. The concentrations of PAHs in the exhaust gases sampled behind a catalytic converter has been determined when the ICE operates in five modes: idle mode, high speed mode, load mode, ICE cold start mode (engine warm-up) and transient mode. Using 92 RON, 95 RON and 98 RON gasoline the effect of the octane number of gasoline on the PAHs content in the exhaust gases has been revealed. The concentration of the most carcinogenic component (benzo(α)pyrene) in the exhaust gases behind a catalytic converter significantly exceeds a reference value of benzo(α)pyrene in the atmospheric air established by the WHO and the EU for ICE in the load mode.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

https://elibrary.ru/item.asp?id=44369782&pf=1

2020 ◽  
Author(s):  
QI CHEN ◽  
◽  
JINTAO SUN ◽  
JIANYU LIU ◽  
BAOMING ZHAO ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Internal Combustion Engines ◽  
Nonequilibrium Plasma ◽  
Combustible Mixture ◽  
Combustion Engines ◽  
Combustion Chemistry ◽  
Microwave Radio ◽  
Different Types ◽  
Gas Molecules ◽  
Ignition And Combustion

Plasma-assisted ignition and combustion, widely applied in gas turbines, scramjets, and internal combustion engines, has been considered as a promising technique in shortening ignition delay time, improving combustion energy efficiency, and reducing emission. Nonequilibrium plasma can excite the gas molecules to higher energy states, directly dissociate or ionize the molecules and, thereby, has the potential to produce reactive species at residence time and location in a combustible mixture and then to efficiently accelerate the overall pyrolysis, oxidation, and ignition. Previous studies have demonstrated the effectiveness of plasma-assisted combustion by using direct current, alternating currant, microwave, radio frequency, and pulsed nanosecond discharge (NSD). Due to the complicated interaction between plasma and combustion in different types of plasma, detailed plasma-combustion chemistry is still not well understood.

scholarly journals The Changes of Ergonomic Engine Vibroacoustic Response Regarding Their Development

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4215
Author(s):  
Radosław Wróbel ◽  
Lech Sitnik ◽  
Monika Andrych-Zalewska ◽  
Łukasz Łoza ◽  
Radostin Dimitrov ◽  
...  
Keyword(s):  
Human Health ◽  
Power Density ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Spectral Power ◽  
Spectral Power Density ◽  
Steering Wheel ◽  
Combustion Engines ◽  
Head Restraint ◽  
Vibroacoustic Response

The article presents the results of research on the vibroacoustic response of internal combustion engines mounted in a vehicle. The vehicles studied belong to popular models, which became available in successive versions. Each group included vehicles of the same model of an older generation (equipped with a naturally aspirated engine) and of a newer generation, including downsized (and turbocharged) engines. Tests in each group were carried out under repeatable conditions on a chassis-load dynamometer. The vibrations were measured using single-axis accelerometers mounted on the steering wheel, engine, and driver’s head restraint mounting. The primary purpose of the study was to verify whether the new generations of vehicles equipped with additional high-speed elements (compressors) generate additional harmonics (especially those within the range potentially affecting travel comfort and human health) and whether there are significant changes in the distribution of spectral power density in the new generations. As the study showed, new generations of vehicles are characterized by a different vibroacoustic response, and the trend of change is the same in each of the families studied.

Sign in / Sign up

Export Citation Format

Share Document