Pre-chamber ignition systems: A methodological proposal to reproduce a reference case in a simplified experimental facility for fundamental studies

2020 ◽  
pp. 146808742097111
Author(s):  
José M Desantes ◽  
J Javier López ◽  
Ricardo Novella ◽  
Jácson Antolini
Keyword(s):  
Engine Speed ◽  
Pressure Rise ◽  
Theoretical Development ◽  
Orifice Diameter ◽  
Limited Information ◽  
Flow Area ◽  
Governing Parameter ◽  
One Dimensional ◽  
Jet Penetration ◽  
Jet Characteristics

To further understand the processes and phenomena taking place in the pre-chamber (PC) ignition concept, many studies under simplified conditions have been carried out in different experimental facilities (e.g. constant volume chambers and rapid compression machines). However limited information is provided about how the volume, orifice diameter and number of orifices were defined, raising the question whether the results are representative of engine-like conditions or not. This novel study arises from the necessity to determine a methodology to reproduce a reference pre-chamber, preserving as much as possible its jet characteristics. A theoretical development based on the first law of thermodynamics has been performed, and a relationship between the effective flow area, pre-chamber volume and engine speed is proposed as the governing parameter of the mass exchange between chambers. Besides, relaying on the know-how of gas jets, a relationship between the orifice diameter, jet tip penetration and engine speed is suggested as the criterion to preserve the relative jet penetration (respect to the distance from the PC hole to the combustion chamber walls). A numerical validation of these assumptions was carried out using a one-dimensional flow calculator to estimate the thermodynamic properties and mass transfer between chambers, and a one-dimensional spray model to estimate the penetration of the PC combustion products jets. Finally, preserving the ratio between the total area of the PC holes and the product of the PC volume and the engine speed for two pre-chamber geometries, an identical pressure rise rate, in an angular basis, is achieved in both pre-chambers. Furthermore, the same relative jet penetration rate, in an angular basis, can be also achieved, even under different engine speeds, when the ratio between the orifice diameter and the product of the square of the jet free length and the engine speed is preserved.

scholarly journals Modeling a fuel injector for a two-stroke diesel engine

2017 ◽  
Vol 170 (3) ◽  
pp. 147-153
Author(s):  
Rafał SOCHACZEWSKI ◽  
Zbigniew CZYŻ ◽  
Ksenia SIADKOWSKA
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Fuel Injection ◽  
Maximum Load ◽  
Fuel Injector ◽  
Dimensional Model ◽  
Flow Area ◽  
Fuel Mass ◽  
One Dimensional ◽  
Injector Nozzle

This paper discusses the modeling of a fuel injector to be applied in a two-stroke diesel engine. A one-dimensional model of a diesel injector was modeled in the AVL Hydsim. The research assumption is that the combustion chamber will be supplied with one or two spray injectors with a defined number of nozzle holes. The diameter of the nozzle holes was calculated for the defined options to provide a correct fuel amount for idling and the maximum load. There was examined the fuel mass per injection and efficient flow area. The studies enabled us to optimize the injector nozzle, given the option of fuel injection into the combustion chamber to be followed.

Effect of Carbon Dioxide on the Laminar Burning Speed of Propane–Air Mixtures

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Sai C. Yelishala ◽  
Ziyu Wang ◽  
Hameed Metghalchi ◽  
Yiannis A. Levendis ◽  
Kumaran Kannaiyan ◽  
...  
Keyword(s):  
High Speed ◽  
Pressure Rise ◽  
Gas Temperature ◽  
Cmos Camera ◽  
Primary Input ◽  
One Dimensional ◽  
Schlieren System ◽  
Co2 Concentrations ◽  
Constant Volume Chamber ◽  
Laminar Burning Speed

This experimental research examined the effect of CO2 as a diluent on the laminar burning speed of propane–air mixtures. Combustion took place at various CO2 concentrations (0–80%), different equivalence ratios (0.7<ϕ<1.2) and over a range of temperatures (298–420 K) and pressures (0.5–6.2 atm). The experiments were performed in a cylindrical constant volume chamber with a Z-shaped Schlieren system, coupled with a high-speed CMOS camera to capture the propagation of the flames at speeds up to 4000 frames per second. The flame stability of these mixtures at different pressures, equivalence ratios, and CO2 concentrations was also studied. Only laminar, spherical, and smooth flames were considered in measuring laminar burning speed. Pressure rise data as a function of time during the flame propagation were the primary input of the multishell thermodynamic model for measuring the laminar burning speed of propane-CO2-air mixtures. The laminar burning speed of such blends was observed to decrease with the addition of CO2 and to increase with the gas temperature. It was also noted that the laminar burning speed decreases with increasing pressure. The collected experimental data were compared with simulation data obtained via a steady one-dimensional (1D) laminar premixed flame code from Cantera, using a detailed H2/CO/C1–C4 kinetics model encompassing 111 species and 784 reactions.

One-Dimensional Simulation of the Combustion Process in an Engine Cylinder with Ethanol

2014 ◽  
Vol 660 ◽  
pp. 447-451
Author(s):  
Akasyah M. Kathri ◽  
Rizalman Mamat ◽  
Amir Aziz ◽  
Azri Alias ◽  
Nik Rosli Abdullah
Keyword(s):  
Diesel Engine ◽  
Alternative Fuels ◽  
Engine Speed ◽  
Combustion Process ◽  
Cylinder Pressure ◽  
Ethanol Fuel ◽  
One Dimensional ◽  
Engine Cylinder ◽  
Dimensional Simulation ◽  
The One

The diesel engine is one of the most important engines for road vehicles. The engine nowadays operates with different kinds of alternative fuels, such as natural gas and biofuel. The aim of this article is to study the combustion process that occurs in an engine cylinder of a diesel engine when using biofuel. The one-dimensional numerical analysis using GT-Power software is used to simulate the commercial four-cylinder diesel engine. The engine operated at high engine load and speed. The ethanol fuel used in the simulation is derived from the conventional ethanol fuel properties. The analysis of simulations includes the cylinder pressure, combustion temperature and rate of heat release. The simulation results show that in-cylinder pressure and temperature for ethanol is higher than for diesel at any engine speed. However, the mass fraction of ethanol burned is similar to that of diesel. MFB only affects the engine speed.

scholarly journals Application of Transient and Dynamic Simulations to the U.S. Army T55-L-712 Helicopter Engine

1996 ◽  
Author(s):  
S. A. Savelle ◽  
G. D. Garrard
Keyword(s):  
Time Dependent ◽  
Limited Information ◽  
Component Level ◽  
Dynamic Simulations ◽  
Engine Operation ◽  
Turbine Engine ◽  
One Dimensional ◽  
Engine Simulation ◽  
Engine Model ◽  
The U.S

The T55-L-712 turboshaft engine, used in the U.S. Army CH-47D Chinook helicopter, has been simulated using version 3.0 of the Advanced Turbine Engine Simulation Technique (ATEST) and version 1.0 of the Aerodynamic Turbine Engine Code (ATEC). The models simulate transient and dynamic engine operation from idle to maximum power and run on an IBM-compatible personal computer. ATEST is a modular one-dimensional component-level transient turbine engine simulation. The simulation is tailored to a specific engine using engine-specific component maps and an engine-specific supervisory subroutine that defines component interrelationships. ATEC is a one-dimensional, time-dependent, dynamic turbine engine simulation. ATEC simulates the operation of a gas turbine by solving the one-dimensional, time dependent Euler equations with turbomachinery source terms. The simulation uses elemental control volumes at the sub-component level (e.g. compressor stage). The paper discusses how limited information from a variety of sources was adapted for use in the T55 simulations and how commonality between the models allowed reuse of the same material. The first application of a new turbine engine model, ATEC, to a specific engine is also discussed. Calibration and operational verification of the simulations will be discussed, along with the status of the simulations.

Jet-Penetration in Prechamber-Ignited Lean Large-Bore Natural Gas Engines

2012 ◽  
Author(s):  
S. Kammerstätter ◽  
S. Bauer ◽  
T. Sattelmayer
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Reaction Zone ◽  
Pressure Rise ◽  
Chamber Pressure ◽  
Main Chamber ◽  
Penetration Length ◽  
Ignition Probability ◽  
Natural Gas Engines ◽  
Jet Penetration

Combustion in lean large-bore natural gas engines is usually initiated by gas-scavenged prechambers. The hot reacting products of the combustion in the prechamber penetrate the main chamber as reacting jets, providing high ignition energy for the lean main chamber charge. The shape and intensity of the reaction zone in these jets are the key elements for efficient ignition and heat release in the main chamber. The influence of geometrical and operational parameters on the reaction during jet penetration was investigated in detail. As the periodically chargeable high pressure combustion cell used in the study provides full optical access to the entire main chamber the evolution of the spatial distribution of the reaction zones was investigated in terms of OH*-chemiluminescence. As jet penetration is a very fast and highly transient process the emission of OH* was recorded at a frequency of f = 30000 Hz. The macroscopic reaction zone parameters in the jet region (penetration length and angle, reacting area and light emission) reveal the influence of orifice size and prechamber gas injection on the heat release in the shear layer between the jet and the lean charge in the main chamber. In addition, the influence of the development of the reaction in these zones on the ignition probability and the main chamber pressure rise is shown. With an appropriate selection of the combination of the prechamber orifice geometry and the operating parameters significant improvements of ignition probability and heat release in the main chamber were obtained.

scholarly journals DISCOURSE ON TELEVISION TALK SHOWS: GENRE OR FORMAT

2020 ◽  
Vol 16 (3) ◽  
pp. 124-133
Author(s):  
Tatyana Parsadanova
Keyword(s):  
Art History ◽  
Emotional State ◽  
Point Of View ◽  
Third Party ◽  
Talk Shows ◽  
Theoretical Development ◽  
One Dimensional ◽  
Television Production ◽  
Production Company ◽  
Broadcasting Schedule

Different approaches to the analysis of television production - one-dimensional and multi-dimensional, exist. All television products are classified by purpose, format, way, and frequency of display, audience, genre, country of production, by who it was produced - the channel itself, or a third-party production company, whether this project is licensed or original. In recent years, Russian TV channels have been broadcasting a large number of conversational TV programs - talk shows. In the programmed broadcasting schedule of some TV channels, they take about 9 hours of airtime, and this is without repetitions. These projects can also be classified in several directions. A discussion between people on a particular topic, which includes elements of such genres as interviews and conversation, is the main essence of a talk show. The debate is a recognized genre of analytical journalism, but at the same time, many talk shows are also defined as a genre. The theory of genre is one of the most significant theoretical development areas in art history, but no single, generally accepted definition exists. Some people believe that the tasks of modern talk shows are well known. This is primarily a desire to make a comprehensively exciting television program with elements of intrigue from a primitive topic, to attract attention and a desire to form a specific attitude to the problem under discussion. The author has a different opinion on some points. Indeed, any show is based on attracting attention. For such projects, the presence of viewers in the studio became a kind of confirmation of the audience's interest in the topic and the opportunity to include them in the discussion, to achieve social commonality. However, from the author's point of view, greater attention must be paid to the idea what the producer wants to convey to the audience and how he wants to see it in the future, to the content - with what information and in what genre to do the project, and to the understanding in what form/format to make the content. At the same time, it is essential to remember that according to the theory of V.Behterev, the process of making people have a specific emotional state occurs faster and more efficiently than an attempt to convince them with the help of logical reasoning.

Operating Limits of Spark-Assisted Compression Ignition Combustion Under Boosted Ultra-EGR Dilute Conditions in a Negative Valve Overlap Engine

2019 ◽  
Author(s):  
Vassilis Triantopoulos ◽  
Jason B. Martz ◽  
Jeff Sterniak ◽  
George Lavoie ◽  
Dennis N. Assanis ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Engine Speed ◽  
Pressure Rise ◽  
Stability Limit ◽  
Maximum Pressure ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Temperature Combustion ◽  
Operating Limits

Abstract Spark-assisted compression ignition (SACI) is a low temperature combustion mode that can offer thermal efficiency improvements and lower nitrogen oxide emissions compared to conventional spark-ignited combustion. However, the SACI operating range is often limited due to excessive pressure rise rates driven by rapid heat release rates. Well-controlled experiments were performed to investigate the SACI operating limits under previously unexplored boosted, stoichiometric, EGR dilute conditions, where low temperature combustion engines promise high thermodynamic efficiencies. At higher intake boost, the SACI high load limit shifted towards lower fuel-to-charge equivalence ratio mixtures, creating a larger gap between the conventional spark-ignition EGR dilution limit and the boosted SACI operating limits. Combustion phasing retard was very effective at reducing maximum pressure rise rate levels until the stability limit, primarily due to slower end-gas burn rates. Gross fuel conversion efficiency improvements up to 10% were observed by using intake boost for either load expansion or dilution extension. Changes in engine speed necessitated changes in unburned gas temperature to match autoignition timing, but were shown to have negligible impact on the heat release profile on a crank angle basis. Lower engine speeds were favorable for load expansion, as time-based peak pressure rise rates scaled with engine speed.

Aerodynamic Performance Prediction of Transonic Axial Multistage Compressors Based on One-Dimensional Meanline Method

2020 ◽  
Author(s):  
Yingying Zhang ◽  
Shijie Zhang ◽  
Yunhan Xiao
Keyword(s):  
Performance Prediction ◽  
Pressure Rise ◽  
Direct Calculation ◽  
One Dimensional ◽  
Axial Compressors ◽  
Surge Margin ◽  
Multistage Compressors ◽  
Aerodynamic Parameters ◽  
And Performance ◽  
The One

Abstract The one-dimensional meanline method is of great importance for the design and performance prediction of multistage axial compressors. The models adopted in it, such as incidence, deviation and loss, considering real-fluid effects, determine whether the compressors’ operating behavior can be simulated accurately or not. This paper describes an improved meanline stage-stacking approach for the modelling of modern transonic axial multistage compressors. The improvement embodied in this study is mainly focused on deviation and surge margin prediction, which is the result of a combination of the previous models and models’ correction. One of the coefficients in the deviation angle model is corrected. A new surge model, different from the well-known maximum static pressure rise method of Koch and Smith, is introduced into this program and its advantage lies in higher accuracy and direct calculation instead of proposing a judgment criterion. Three well-documented NASA axial transonic compressors are calculated by this meanline method, and the speedlines and aerodynamic parameters are compared with the experimental data to verify the method presented in this paper. A discussion of the result then follows.

Design and Flow Analysis of a Rim-Driven Hub-Less Axial Flow Fan

2021 ◽  
Author(s):  
Hanqing Yang ◽  
Yijun Wang ◽  
Jinju Sun ◽  
Bangyi Wang ◽  
Youwei He ◽  
...  
Keyword(s):  
Design Method ◽  
Flow Behavior ◽  
Tangential Velocity ◽  
Axial Flow ◽  
Pressure Rise ◽  
Low Noise ◽  
Flow Mechanism ◽  
Axial Flow Fan ◽  
Flow Area ◽  
Overall Performance

Abstract Rim-driven hub-less fans have newly emerged as the most compact type of axial flow fans, which permits flexible configuration arrangements, large relative flow area and low-noise level operation. However, previous publications on rim-driven axial flow fans are rarely found in the open literature, and the flow mechanism and design principle of such promising fans haven’t yet been well-understood and established. This paper has been focused on a preliminary study of the rim-driven axial flow fan design and flow mechanism. A design method of the rim-driven fans is proposed on the basis of the isolated airfoil scheme and the variable circulation rule. It is further incorporated into a FORTRAN code and suited for designing the rim-driven hub-less fans of low-pressure levels. For validation purpose, a conventional hub-type fan is redesigned with the developed method and its flow behavior and overall performance are investigated numerically. A parametric study on the designed fan is further conducted respectively for the tangential velocity difference at mean span, circulation exponent and sweep angle and their influence on the fan flow characteristics and overall performance are explored and highlighted. On such a basis, the developed design method for the rim-driven axial flow fan is further improved. In comparison with the conventionally designed fan at identical rotating speed, significant comprehensive gains are arising from the redesigned fan of hub-less configuration: the overall pressure rise and static pressure efficiency is enhanced respectively by 6.2% and 11.5%, whereas the diameter of the fan is reduced by 12.5% simultaneously. It is demonstrated that the rim-driven hub-less configuration is promising for the enhancing the fan overall performance with even reduced dimensions.

scholarly journals Assessing the optimum combustion under constrained conditions

2018 ◽  
Vol 21 (5) ◽  
pp. 811-823 ◽  
Author(s):  
Pablo Olmeda ◽  
Jaime Martín ◽  
Ricardo Novella ◽  
Diego Blanco-Cavero
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Heat Release ◽  
Engine Speed ◽  
Direct Injection ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Low Load ◽  
Negative Effect ◽  
Constrained Conditions

This work studies the optimum heat release law of a direct injection diesel engine under constrained conditions. For this purpose, a zero-dimensional predictive model of a diesel engine is coupled to an optimization tool used to shape the heat release law in order to optimize some outputs (maximize gross indicated efficiency and minimize NO x emissions) while keeping several restrictions (mechanical limits such as maximum peak pressure and maximum pressure rise rate). In a first step, this methodology is applied under different heat transfer scenarios without restrictions to evaluate the possible gain obtained through the thermal isolation of the combustion chamber. Results derived from this study show that heat transfer has a negative effect on gross indicated efficiency ranging from −4% of the fuel energy ( ṁfHv), at high engine speed and load, up to −8% ṁfHv, at low engine speed and load. In a second step, different mechanical limits are applied resulting in a gross indicated efficiency worsening from −1.4% ṁfHv up to −2.8% ṁfHv compared to the previous step when nominal constraints are applied. In these conditions, a temperature swing coating that covers the piston top and cylinder head is considered obtaining a maximum gross indicated efficiency improvement of +0.5% ṁfHv at low load and engine speed. Finally, NO x emissions are also included in the optimization obtaining the expected tradeoff between gross indicated efficiency and NO x. Under this optimization, cutting down the experimental emissions by 50% supposes a gross indicated efficiency penalty up to −8% ṁfHv when compared to the optimum combustion under nominal limits, while maintaining the experimental gross indicated efficiency allows to reduce the experimental emissions 30% at high load and 65% at low load and engine speed.

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