scholarly journals Simultaneous High-Speed Formaldehyde PLIF and Schlieren Imaging of Multiple Injections From an ECN Spray D Injector

2020 ◽  
Author(s):  
Noud Maes ◽  
Hyung Sub Sim ◽  
Lukas Weiss ◽  
Lyle Pickett
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Combustion Products ◽  
Schlieren Imaging ◽  
Multiple Injections ◽  
Soot Precursors ◽  
Planar Laser ◽  
Temperature Combustion ◽  
Polycyclic Aromatic ◽  
High Temperature Combustion

Abstract The interaction of multiple injections in a diesel engine facilitates a complex interplay between freshly introduced fuel, previous combustion products, and overall combustion. To improve understanding of the relevant processes, high-speed Planar Laser-Induced Fluorescence (PLIF) with 355-nm excitation of formaldehyde and Polycyclic Aromatic Hydrocarbon (PAH) soot precursors is applied to multiple injections of n-dodecane from Engine Combustion Network Spray D, characterized by a converging 189-μm nozzle. High-speed schlieren imaging is applied simultaneously with 50-kHz PLIF excitation to visualize the spray structures, jet penetration, and ignition processes. For the first injection, formaldehyde (as an indicator of low-temperature chemistry) is first found in the jet periphery, after which it quickly propagates through the center of the jet, towards the jet head prior to high-temperature ignition. At second-stage ignition, downstream formaldehyde is consumed rapidly and upstream formaldehyde develops into a quasi-steady structure for as long as the momentum flux from the injector continues. Since the first injection in this work is relatively short, differences to a single long injection are readily observed, ultimately resulting in high-temperature combustion and PAH structures appearing farther upstream after the end of injection. For the second injection in this work, the first formaldehyde signal is significantly advanced because of the entrained high-temperature combustion products, and an obvious premixed burn event does not occur. The propensity for combustion recession after the end of the first injection changes significantly with ambient temperature, thereby affecting the level of interaction between the first- and second injection.

scholarly journals Temperature Fields of the Droplets and Gases Mixture

2020 ◽  
Vol 10 (7) ◽  
pp. 2212
Author(s):  
Roman S. Volkov ◽  
Ivan S. Voytkov ◽  
Pavel A. Strizhak
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Air Flow ◽  
Combustion Products ◽  
Temperature Fields ◽  
Vapor Mixture ◽  
Heated Air ◽  
Observation Area ◽  
Temperature Combustion ◽  
High Temperature Combustion

In this research, we obtain gas–vapor mixture temperature fields generated by blending droplets and high-temperature combustion products. Similar experiments are conducted for droplet injection into heated air flow. This kind of measurement is essential for high-temperature and high-speed processes in contact heat exchangers or in liquid treatment chambers, as well as in firefighting systems. Experiments are conducted using an optical system based on Laser-Induced Phosphorescence as well as two types of thermocouples with a similar measurement range but different response times (0.1–3 s) and accuracy (1–5 °C). In our experiments, we inject droplets into the heated air flow (first scheme) and into the flow of high-temperature combustion products (second scheme). We concentrate on the unsteady inhomogeneous temperature fields of the gas–vapor mixture produced by blending the above-mentioned flows and monitoring the lifetime of the relatively low gas temperature after droplets passes through the observation area. The scientific novelty of this research comes from the first ever comparison of the temperature measurements of a gas–vapor–droplet mixture obtained by contact and non-contact systems. The advantages and limitations of the contact and non-contact techniques are defined for the measurement of gas–vapor mixture temperature.

scholarly journals Features of thermodynamic and thermal processes in hydrogen combustion units and systems on their basis

2021 ◽  
Vol 2039 (1) ◽  
pp. 012032
Author(s):  
A I Schastlivtsev ◽  
V I Borzenko
Keyword(s):  
High Temperature ◽  
Combustion Products ◽  
Hydrogen Combustion ◽  
Thermal Processes ◽  
Steam Generators ◽  
Temperature Combustion ◽  
Main Components ◽  
High Temperature Combustion

Abstract The main types and designs of hydrogen combustion units (HCU), including hydrogen-oxygen steam generators, superheaters and air heaters of various power levels, are considered. The main problems arising in the development, creation and testing of such installations are determined, including the problems of cooling the most heat-stressed units, mixing of the main components of the fuel and oxidizer, mixing of high-temperature combustion products and ballasting components, problems associated with the completeness of hydrogen combustion and ensuring safety during operation.

Experimental Investigation of Flow Phenomena of a Single Fuel Jet in Cross-Flow During Highly Preheated Air Combustion Conditions

2006 ◽  
Vol 129 (2) ◽  
pp. 556-564 ◽  
Author(s):  
Magnus Mörtberg ◽  
Wlodzimierz Blasiak ◽  
Ashwani K. Gupta
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Flow Dynamics ◽  
High Temperature Air Combustion ◽  
Fuel Jet ◽  
Temperature Combustion ◽  
High Temperature Combustion

Particle image velocimetry and a spectroscopy technique has been used to obtain information on the flow dynamics and flame thermal signatures of a fuel jet injected into a cross-flow of normal temperature and very high-temperature combustion air. Flame fluctuations were obtained using a high-speed camera and then performing fast Fourier transform on the signal. High-temperature air combustion has been demonstrated to provide significant energy savings, higher heat flux, and reduction of pollution and equipment size of industrial furnaces. The dynamics of flow associated with high temperature combustion air conditions (for mean velocity, axial strain rate and vorticity) has been obtained in two-dimensional using propane and methane as the fuels. The data have been compared with normal temperature combustion air case, including the nonburning case. A specially designed experimental test furnace facility was used to provide well-controlled conditions and allowed air preheats to 1100°C using regenerative burners. Four different experimental cases have been examined. The momentum flux ratio between the burning and nonburning conditions was kept constant to provide comparison between cases. The results provide the role of high-temperature combustion air on the dynamics of the flow, turbulence, and mixing under nonburning and combustion conditions. The data provide the direct role of combustion on flow dynamics, turbulence, and flame fluctuations. High-temperature combustion air at low-oxygen concentration showed larger flame volume with less fluctuation than normal or high-temperature normal air cases. High-temperature combustion air technology prolongs mixing in the combustion zone to enhance the flame volume, reduce flame fluctuations, and to provide uniform flow and thermal characteristics. This information assists in model validation and model development for new applications and technology development using high-temperature air combustion principles.

Features of transformation of water projectiles moving through high-temperature combustion products

2016 ◽  
Vol 42 (3) ◽  
pp. 256-259 ◽  
Author(s):  
R. S. Volkov ◽  
M. V. Zabelin ◽  
G. V. Kuznetsov ◽  
P. A. Strizhak
Keyword(s):  
High Temperature ◽  
Combustion Products ◽  
Temperature Combustion ◽  
High Temperature Combustion
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