Fuel Proximity Effect on Hot-Jet Ignition in a Wave Rotor Constant Volume Combustor

2012 ◽  
Author(s):  
Sameera Wijeyakulasuriya ◽  
Tarek Elharis ◽  
Mohamed Nalim
Keyword(s):  
Proximity Effect ◽  
Constant Volume ◽  
Wave Rotor ◽  
Hot Jet Ignition

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.

Application of the Geared Turbofan With Constant Volume Combustor on Short-Range Aircraft: A Feasibility Study

2009 ◽  
Author(s):  
Fernando Colmenares Quintero ◽  
Rob Brink ◽  
Stephen Ogaji ◽  
Pericles Pilidis ◽  
Juan Carlos Colmenares Quintero ◽  
...  
Keyword(s):  
Feasibility Study ◽  
Short Range ◽  
Operating Cost ◽  
Constant Volume ◽  
Superior Performance ◽  
Wave Rotor ◽  
Environmental Aspects ◽  
Direct Operating Cost ◽  
Combustion Technology ◽  
Further Development

Recently a considerable effort was made to understand the gas- and thermodynamics of wave rotor combustion technology. Pressure-gain combustors potentially have superior performance over conventional combustors due to their unsteady flow behaviour. Wave rotor combustion provides semi-constant volume combustion and could be integrated in the steady-flow gas turbine. However, a feasibility study to assess the economical and environmental aspects of this concept has not been conducted for short-range missions. Preliminary Multidisciplinary Design Framework was developed to assess novel and radical engine cycles. The tool comprises modules to evaluate noise, emissions and environmental impact. Uncertainty can be accounted for with Monte Carlo simulation. The geared turbofan with constant volume combustor is simulated and benchmarked against a baseline geared turbofan engine. Results indicate that the former complies with CAEP/6 and FAR Part 36 regulations for noise and emissions. Furthermore, acquisition cost of the engine is higher, but engine direct operating cost decreases by 25.2%. The technology requires further development to meet future noise and emissions requirements.

Wave Rotor Combustor Test Rig Preliminary Design

2004 ◽  
Author(s):  
Berrak Alparslan ◽  
M. Razi Nalim ◽  
Philip H. Snyder
Keyword(s):  
Computational Models ◽  
Combustion Process ◽  
Constant Volume ◽  
Operating Conditions ◽  
Experimental Program ◽  
Preliminary Design ◽  
Wave Rotor ◽  
Test Rig ◽  
Operating Cycle ◽  
And Performance

Pressure gain combustion in a wave rotor approaching the thermodynamic ideal of constant volume combustion has been proposed to significantly enhance the performance of gas turbine engines. A computational and experimental program is currently being conducted to investigate the combustion process and performance of a wave rotor with detonative and near-detonative internal combustion. An innovative and flexible preliminary design of the test rig is presented to demonstrate the operation and performance of the system. A preliminary design method based on a sequence of computational models is used to design wave processes for testing in the rig and to define rig geometry and operating conditions. The operating cycle allows for propagation of the combustion front from the exit end of the combustion channel to the inlet end. This is similar to and motivated by the Constant Volume Combustor (CVC) concept that seeks to produce a relatively uniform set of outflow conditions in both spatial and time coordinates.

scholarly journals Two-Dimensional Flow and NOx Emissions in Deflagrative Internal Combustion Wave Rotor Configurations

2003 ◽  
Vol 125 (3) ◽  
pp. 720-733 ◽  
Author(s):  
K. Pekkan ◽  
M. R. Nalim
Keyword(s):  
Fuel Injection ◽  
Design Feature ◽  
Constant Volume ◽  
Pollutant Emissions ◽  
No Production ◽  
Two Dimensional ◽  
Wave Rotor ◽  
Dimensional Flow ◽  
Wall Boundary Conditions ◽  
Two Dimensional Flow

A wave rotor is proposed for use as a constant volume combustor. A novel design feature is investigated as a remedy for hot gas leakage, premature ignition, and pollutant emissions that are possible in this class of unsteady machines. The base geometry involves fuel injection partitions that allow stratification of fuel/oxidizer mixtures in the wave rotor channel radially, enabling pilot ignition of overall lean mixture for low NOx combustion. In this study, available turbulent combustion models are applied to simulate approximately constant volume combustion of propane and resulting transient compressible flow. Thermal NO production histories are predicted by simulations of the STAR-CD code. Passage inlet/outlet/wall boundary conditions are time-dependent, enabling the representation of a typical deflagrative internal combustor wave rotor cycle. Some practical design improvements are anticipated from the computational results. For a large number of derivative design configurations, fuel burn rate, two-dimensional flow and emission levels are evaluated. The sensitivity of channel combustion to initial turbulence levels is evaluated.

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.

scholarly journals Improvements in the turbo-engine by replacement of conventional combustion chamber by a pulse combustion chamber

2013 ◽  
Vol 60 (4) ◽  
pp. 481-494
Author(s):  
Damian Łapinski ◽  
Janusz Piechna
Keyword(s):  
Combustion Chamber ◽  
Analytical Model ◽  
Combustion Process ◽  
Constant Volume ◽  
Wave Rotor ◽  
Additional Energy ◽  
Pulse Combustor ◽  
Calculation Results ◽  
Pulse Combustion ◽  
Turbo Engine

Abstract This paper comprises description of the turbo engine and evaluation of its analytical model. The analytical model was created to establish a benchmark for further evaluation of a wave rotor combustor (at constant volume). The wave rotor combustor concept was presented and discussed. Advantages of combustion at constant volume were described as well as the basic turbo engine updates required to reflect pulse combustor application. The calculation results for analytical model of a basic engine, and that equipped with pulse combustor are included in this paper. The paper describes the required changes in the engine structure and construction and the estimated thermodynamic improvements. Axial-type pulse multi-chamber combustion unit increasing the pressure and temperature of gases requires a special additional turbine utilizing additional energy and forming the interface between the standard compressor-turbine unit. Performance calculations done for an existing GTD-350 engine showed that constant-volume combustion process is valuable

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