Optical Investigation of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Mohammad Fatouraie ◽  
Margaret Wooldridge
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Engine Performance ◽  
Optical Investigation ◽  
Release Rates ◽  
High Speed Imaging ◽  
Engine Operation ◽  
Auto Ignition ◽  
Spark Timing ◽  
Combustion Properties

Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects of 100% indolene and 70% indolene/30% ethanol blends on the ignition and combustion properties during SA HCCI operation. The spark assist effects are compared to baseline HCCI operation for each blend by varying spark timing at different fuel/air equivalence ratios ranging from Φ = 0.4–0.5. High speed imaging is used to understand connections between spark initiated flame propagation and heat release rates. Ethanol generally improves engine performance with higher net indicated mean effective pressure (IMEPn) and higher stability compared to 100% indolene. SA advances phasing within a range of ∼5 crank angle degrees (CAD) at lower engine speeds (700 rpm) and ∼11 CAD at higher engine speeds (1200 rpm). SA does not affect heat release rates until immediately (within ∼5 CAD) prior to auto-ignition. Unlike previous SA HCCI studies of indolene fuel in the same engine, flames were not observed for all SA conditions.

Optical Investigation of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI

2013 ◽  
Author(s):  
Mohammad Fatouraie ◽  
Margaret S. Wooldridge
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Engine Performance ◽  
Optical Investigation ◽  
Release Rates ◽  
High Speed Imaging ◽  
Engine Operation ◽  
Spark Timing ◽  
Combustion Properties ◽  
Ethanol Blends

Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects of 100% indolene and 70% indolene/30% ethanol blends on the ignition and combustion properties during SA HCCI operation. The spark assist effects are compared to baseline HCCI operation for each blend by varying spark timing at different fuel/air equivalence ratios ranging from ϕ = 0.4–0.5. High speed imaging is used to understand connections between spark initiated flame propagation and heat release rates. Ethanol generally improves engine performance with higher IMEPn and higher stability compared to 100% indolene. SA advances phasing within a range of ∼5 CAD at lower engine speeds (700 RPM) and ∼11 CAD at higher engine speeds (1200 RPM). SA does not affect heat release rates until immediately (within ∼5 CAD) prior to autoignition. Unlike previous SA HCCI studies of indolene fuel in the same engine, flames were not observed for all SA conditions.

High Speed Imaging of Forced Ignition Kernels in Non-Uniform Jet Fuel/Air Mixtures

2017 ◽  
Author(s):  
Sheng Wei ◽  
Brandon Sforzo ◽  
Jerry Seitzman
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Air Flow ◽  
Cetane Number ◽  
High Energy ◽  
Liquid Fuels ◽  
High Speed Imaging ◽  
Ignition Probability ◽  
Turbine Engine ◽  
Planar Laser

This paper describes experimental measurements of forced ignition of prevaporized liquid fuels in a well-controlled facility that incorporates non-uniform flow conditions similar to those of gas turbine engine combustors. The goal here is to elucidate the processes by which the initially unfueled kernel evolves into a self-sustained flame. Three fuels are examined: a conventional Jet-A and two synthesized fuels that are used to explore fuel composition effects. A commercial, high-energy recessed cavity discharge igniter located at the test section wall ejects kernels at 15 Hz into a preheated, striated crossflow. Next to the igniter wall is an unfueled air flow; above this is a premixed, prevaporized, fuel-air flow, with a matched velocity and an equivalence ratio near 0.75. The fuels are prevaporized in order to isolate chemical effects. Differences in early ignition kernel development are explored using three, synchronized, high-speed imaging diagnostics: schlieren, emission/chemiluminescence, and OH planar laser-induced fluorescence (PLIF). The schlieren images reveal rapid entrainment of crossflow fluid into the kernel. The PLIF and emission images suggest chemical reactions between the hot kernel and the entrained fuel-air mixture start within tens of microseconds after the kernel begins entraining fuel, with some heat release possibly occurring. Initially, dilution cooling of the kernel appears to outweigh whatever heat release occurs; so whether the kernel leads to successful ignition or not, the reaction rate and the spatial extent of the reacting region decrease significantly with time. During a successful ignition event, small regions of the reacting kernel survive this dilution and are able to transition into a self-sustained flame after ∼1–2 ms. The low aromatic/low cetane number fuel, which also has the lowest ignition probability, takes much longer for the reaction zone to grow after the initial decay. The high aromatic, more easily ignited fuel, shows the largest reaction region at early times.

Fuel Influence on Targeted Gas Turbine Combustion Properties: Part I — Detailed Diagnostics

2014 ◽  
Author(s):  
Thomas Mosbach ◽  
Victor Burger ◽  
Barani Gunasekaran
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Leading Edge ◽  
Operating Conditions ◽  
Optical Measurements ◽  
Test Facility ◽  
Research Centre ◽  
High Speed Imaging ◽  
Combustion Properties ◽  
First Results

The threshold combustion performance of different fuel formulations under simulated altitude relight conditions were investigated in the altitude relight test facility located at the Rolls-Royce plc. Strategic Research Centre in Derby, UK. The combustor employed was a twin-sector representation of an RQL gas turbine combustor. Eight fuels including conventional crude-derived Jet A-1 kerosene, synthetic paraffinic kerosenes (SPKs), linear paraffinic solvents, aromatic solvents and pure compounds were tested. The combustor was operated at sub-atmospheric air pressure of 41 kPa and air temperature of 265 K. The temperature of all fuels was regulated to 288 K. The combustor operating conditions corresponded to a low stratospheric flight altitude near 9 kilometres. The experimental work at the Rolls-Royce (RR) test-rig consisted of classical relight envelope ignition and extinction tests, and ancillary optical measurements: Simultaneous high-speed imaging of the OH* chemiluminescence and of the soot luminosity was used to visualize both the transient combustion phenomena and the combustion behaviour of the steady burning flames. Flame luminosity spectra were also simultaneously recorded with a spectrometer to obtain information about the different combustion intermediates and about the thermal soot radiation curve. This paper presents first results from the analysis of the weak extinction measurements. Further detailed test fuel results are the subject of a separate complementary paper [1]. It was found in general that the determined weak extinction parameters were not strongly dependent on the fuels investigated, however at the leading edge of the OH* chemiluminescence intensity development in the pre-flame region fuel-related differences were observed.

scholarly journals Oxygen-Enriched Diesel Engine Performance: A Comparison of Analytical and Experimental Results

1991 ◽  
Vol 113 (3) ◽  
pp. 365-369 ◽  
Author(s):  
R. R. Sekar ◽  
W. W. Marr ◽  
D. N. Assanis ◽  
R. L. Cole ◽  
T. J. Marciniak ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Experimental Studies ◽  
Engine Performance ◽  
Oxygen Enrichment ◽  
Published Data ◽  
Particulate Emissions ◽  
Lower Grade ◽  
Nox Emissions ◽  
Release Rates

Use of oxygen-enriched combustion air in diesel engines can lead to significant improvements in power density, as well as reductions in particulate emissions, but at the expense of higher NOx emissions. Oxygen enrichment would also lead to lower ignition delays and the opportunity to burn lower grade fuels. Analytical and experimental studies are being conducted in parallel to establish the optimal combination of oxygen level and diesel fuel properties. In this paper, cylinder pressure data acquired on a single-cylinder engine are used to generate heat release rates for operation under various oxygen contents. These derived heat release rates are in turn used to improve the combustion correlation—and thus the prediction capability—of the simulation code. It is shown that simulated and measured cylinder pressures and other performance parameters are in good agreement. The improved simulation can provide sufficiently accurate predictions of trends and magnitudes to be useful in parametric studies assessing the effects of oxygen enrichment and water injection on diesel engine performance. Measured ignition delays, NOx emissions, and particulate emissions are also compared with previously published data. The measured ignition delays are slightly lower than previously reported. Particulate emissions measured in this series of tests are significantly lower than previously reported.

scholarly journals High-Speed Imaging of Forced Ignition Kernels in Nonuniform Jet Fuel/Air Mixtures

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Sheng Wei ◽  
Brandon Sforzo ◽  
Jerry Seitzman
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Air Flow ◽  
Cetane Number ◽  
High Energy ◽  
Liquid Fuels ◽  
High Speed Imaging ◽  
Ignition Probability ◽  
Turbine Engine ◽  
Planar Laser

This paper describes experimental measurements of forced ignition of prevaporized liquid fuels in a well-controlled facility that incorporates nonuniform flow conditions similar to those of gas turbine engine combustors. The goal here is to elucidate the processes by which the initially unfueled kernel evolves into a self-sustained flame. Three fuels are examined: a conventional Jet-A and two synthesized fuels that are used to explore fuel composition effects. A commercial, high-energy recessed cavity discharge igniter located at the test section wall ejects kernels at 15 Hz into a preheated, striated crossflow. Next to the igniter wall is an unfueled air flow; above this is a premixed, prevaporized, fuel–air flow, with a matched velocity and an equivalence ratio near 0.75. The fuels are prevaporized in order to isolate chemical effects. Differences in early ignition kernel development are explored using three synchronized, high-speed imaging diagnostics: schlieren, emission/chemiluminescence, and OH planar laser-induced fluorescence (PLIF). The schlieren images reveal rapid entrainment of crossflow fluid into the kernel. The PLIF and emission images suggest chemical reactions between the hot kernel and the entrained fuel–air mixture start within tens of microseconds after the kernel begins entraining fuel, with some heat release possibly occurring. Initially, dilution cooling of the kernel appears to outweigh whatever heat release occurs; so whether the kernel leads to successful ignition or not, the reaction rate and the spatial extent of the reacting region decrease significantly with time. During a successful ignition event, small regions of the reacting kernel survive this dilution and are able to transition into a self-sustained flame after ∼1–2 ms. The low-aromatic/low-cetane-number fuel, which also has the lowest ignition probability, takes much longer for the reaction zone to grow after the initial decay. The high-aromatic, more easily ignited fuel, shows the largest reaction region at early times.

Comparative Study on Spray Auto-Ignition of Di-n-Butyl Ether and Diesel Blends at Engine-Like Conditions

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Yuanhang Guan ◽  
Wang Liu ◽  
Dong Han
Keyword(s):  
Heat Release ◽  
Oxygen Concentration ◽  
Pressure Rise ◽  
Fuel Spray ◽  
Release Rates ◽  
Butyl Ether ◽  
Auto Ignition ◽  
Ambient Oxygen ◽  
Ignition And Combustion ◽  
Oxygen Concentrations

Abstract Di-n-butyl ether (DBE), a promising lignocellulosic biofuel, has been suggested as a potential alternative fuel for compression ignition engines. In this study, the spray auto-ignition characteristics of diesel/DBE blends were experimentally measured on a constant volume combustion chamber. Time-resolved pressure traces and heat release rates in fuel spray combustion were measured at changed fuel blending fractions, ambient temperatures, and oxygen concentrations. Further, ignition delay and combustion delay that evaluates fuel spray ignition tendency were derived and compared for different test blends. Experimental results indicated that fuel spray ignition tendency is promoted with DBE addition, evidenced by the advanced pressure rise and heat release processes, and the shortened ignition and combustion delays. Peak heat release rates are fuel-dependent at high ambient oxygen concentrations since the relative fractions of the premixed and diffusive burns alter with changed DBE addition. However, as the oxygen concentration drops to 11%, fuel effects on the peak heat release rates become less noticeable. Reduced ambient oxygen concentration effectively extends fuel ignition and combustion delays, and typical two-stage pressure rises and heat releases are observed for all test blends, as the oxygen concentration drops to 11%.

Homogeneous Charge Catalytic Ignition of Water-Ethanol Blends in a CFR Engine

2009 ◽  
Author(s):  
Edwin Anderson ◽  
Jason Cyr ◽  
Dan Cordon ◽  
Steve Beyerlein
Keyword(s):  
High Speed ◽  
Engine Performance ◽  
High Water ◽  
Operating Characteristics ◽  
Emission Data ◽  
Engine Operation ◽  
Preparation Methods ◽  
Ethanol Injection ◽  
Hc Emissions ◽  
Ethanol Blends

The burning of water ethanol blends has the potential to reduce NOx, CO, and HC emissions while reducing the ethanol fermentation production cost of distillation and dehydration by utilization of these blends. The torch style ignition produced by the catalytic igniter allows for the operation and cold start of an SI engine on ethanol/water fuels up to a 50/50 blend. This paper describes the operating characteristics of a catalytic igniter in a modified Co-operative Fuels Research (CFR) engine. Performance data was evaluated using a high speed in-cylinder combustion pressure analyzer. Emission data for premixed ethanol/water was also compared to separate water and ethanol injection for concentrations of 0–30% water in ethanol. Emissions and performance results for both fuel preparation methods were compared with engine operation on 100% ethanol. Premixed ethanol/water displayed significantly lower NOx and CO emissions and somewhat higher hydrocarbon emissions than separate water and ethanol injection. At a compression ratio of 10:1, the catalytic igniter configuration studied in this work was able to control cycle to cycle pressure variation even at high water fractions.

Experimental Investigation On Cylinder Vibration Analysis, Combustion, Emission and Performance Of An IDI Engine

2017 ◽  
Vol 7 (1) ◽  
pp. 18-36
Author(s):  
Prasada Rao Kancherla ◽  
Venkata Appa Rao Basava
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Engine Performance ◽  
Substantial Improvement ◽  
Engine Operation ◽  
Diesel Injection ◽  
Combustion Emission ◽  
And Performance ◽  
Discrete Part

An experimental study was conducted to evaluate the performance, emissions, combustion and heat release rate of an Indirect Diesel Injection (IDI) engine fuelled with Mahua methyl ester (MME) along with Methanol (M) additive blends. Smoke, NOx, CO, HC and CO2 emissions were recorded and various engine performance parameters were measured. A comparative study was conducted using diesel, MME and Methanol additive blends on an IDI engine. There is substantial improvement can be observed from the net heat and cumulative heat release rate plots in which the 3% additive blend reached the performance of diesel fuel and the corresponding cylinder vibration plots indicated smoother combustion. Five additive blends were tested, the blending ratios of 1/99, 2/98, 3/97, 4/96 and 5/95 (by vol.) and five discrete part load conditions viz. No Load, 0.77 kW, 1.54 kW, 2.31 kW, and 2.70 kW loads without gear box and clutch assembly ensuring stable engine operation. 57% HC, 20% CO, 14% NOx, 27% smoke reductions were observed at 3% additive at maximum opted load (2.70 kW and 1500 rpm) of the engine.

Auto-Ignition of In-Line Injected Hydrogen/Nitrogen Fuel Mixtures at Reheat Combustor Operating Conditions

2015 ◽  
Author(s):  
Christoph Schmalhofer ◽  
Peter Griebel ◽  
Michael Stöhr ◽  
Manfred Aigner ◽  
Torsten Wind
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Design Guidelines ◽  
Operating Conditions ◽  
Fuel Injector ◽  
High Speed Imaging ◽  
Capture Process ◽  
Carrier Medium ◽  
Auto Ignition ◽  
Ignition Limits

De-carbonization of the power generation sector becomes increasingly important in order to achieve the European climate targets. Coal or biomass gasification together with a pre-combustion carbon capture process might be a solution resulting in hydrogen-rich gas turbine (GT) fuels. However, the high reactivity of these fuels poses challenges to the operability of lean premixed gas turbine combustion systems because of a higher auto-ignition and flashback risk. Investigation of these phenomena at GT relevant operating conditions is needed to gain knowledge and to derive design guidelines for a safe and reliable operation. The present investigation focusses on the influence of the fuel injector configuration on auto-ignition and kernel development at reheat combustor relevant operating conditions. Auto-ignition of H2-rich fuels was investigated in the optically accessible mixing section of a generic reheat combustor. Two different geometrical in-line configurations were investigated. In the premixed configuration, the fuel mixture (H2 / N2) and the carrier medium nitrogen (N2) were homogeneously premixed before injection, whereas in the co-flow configuration the fuel (H2 / N2) jet was embedded in a carrier medium (N2 or air) co-flow. High-speed imaging was used to detect auto-ignition and to record the temporal and spatial development of auto-ignition kernels in the mixing section. A high temperature sensitivity of the auto-ignition limits were observed for all configurations investigated. The lowest auto-ignition limits are measured for the premixed in-line injection. Significantly higher auto-ignition limits were determined in the co-flow in-line configuration. The analysis of auto-ignition kernels clearly showed the inhibiting influence of fuel dilution for all configurations.

Investigation of Auto-Ignition of a Pulsed Methane Jet in Vitiated Air Using High-Speed Imaging Techniques

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
W. Meier ◽  
I. Boxx ◽  
C. Arndt ◽  
M. Gamba ◽  
N. Clemens
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Imaging Techniques ◽  
Frame Rate ◽  
Experimental Arrangement ◽  
Single Shot ◽  
Exhaust Gas ◽  
High Speed Imaging ◽  
Auto Ignition ◽  
Flow Field Characteristics

An experimental arrangement for the investigation of auto-ignition of a pulsed CH4 jet in a coflow of hot exhaust gas from a laminar lean premixed H2/air flame at atmospheric pressure is presented. The ignition events were captured by high-speed imaging of the OH∗ chemiluminescence associated with the igniting flame kernels at a frame rate of 5 kHz. The flow-field characteristics were determined by high-speed particle image velocimetry and Schlieren images. Furthermore, high-speed imaging of laser-induced fluorescence of OH was applied to visualize the exhaust gas flow and the ignition events. Auto-ignition was observed to occur at the periphery of the CH4 jet with high reproducibility in different runs concerning time and location. In each measurement run, several hundred consecutive single shot images were recorded from which sample images are presented. The main goals of the study are the presentation of the experimental arrangement and the high-speed measuring systems and a characterization of the auto-ignition events occurring in this system.

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