Parametric Control of Oxyacetylene Flame Profile

2013 ◽  
Vol 845 ◽  
pp. 790-794 ◽  
Author(s):  
Adam Umar Alkali ◽  
Turnad Lenggo Ginta ◽  
Ahmad Majdi Abdul-Rani
Keyword(s):  
Reynolds Number ◽  
Heat Release ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Operating Conditions ◽  
Flame Height ◽  
Empirical Correlations ◽  
Base Diameter ◽  
Parametric Control

Oxyacetylene flame heights which were obtained through representation from a number of camera shots were compared from those estimated from empirical correlations for determining the flame height based on the heat release rate (Q) and flame base diameter (D). Pressure of gas mixtures are purposely changed to obtained a varying flow rate with the flame set to neutral during each routine. It is found that operating conditions like Reynolds number and flow rate influences the profile of the combustion flame.

scholarly journals Effects of Discharge Area and Atomizing Gas Type in Full Cone Twin-Fluid Atomizer on Extinguishing Performance of Heptane Pool Fire under Two Heat Release Rate Conditions in an Enclosed Chamber

2021 ◽  
Vol 11 (7) ◽  
pp. 3247
Author(s):  
Dong Hwan Kim ◽  
Chi Young Lee ◽  
Chang Bo Oh
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Pool Fire ◽  
Sauter Mean Diameter ◽  
Discharge Area ◽  
Fire Extinguishing ◽  
Enclosed Chamber

In this study, the effects of discharge area and atomizing gas type in a twin-fluid atomizer on heptane pool fire-extinguishing performance were investigated under the heat release rate conditions of 1.17 and 5.23 kW in an enclosed chamber. Large and small full cone twin-fluid atomizers were prepared. Nitrogen and air were used as atomizing gases. With respect to the droplet size of water mist, as the water and air flow rates decreased and increased, respectively, the Sauter mean diameter (SMD) of the water mist decreased. The SMD of large and small atomizers were in the range of approximately 12–60 and 12–49 μm, respectively. With respect to the discharge area effect, the small atomizer exhibited a shorter extinguishing time, lower peak surface temperature, and higher minimum oxygen concentration than the large atomizer. Furthermore, it was observed that the effect of the discharge area on fire-extinguishing performance is dominant under certain flow rate conditions. With respect to the atomizing gas type effect, nitrogen and air appeared to exhibit nearly similar extinguishing times, peak surface temperatures, and minimum oxygen concentrations under most flow rate conditions. Based on the present and previous studies, it was revealed that the effect of atomizing gas type on fire-extinguishing performance is dependent on the relative positions of the discharged flow and fire source.

Temperature effects on the mass flow rate in the SBI and similar heat-release rate test equipment

2007 ◽  
Vol 31 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Bart J. G. Sette ◽  
Erwin Theuns ◽  
Bart Merci ◽  
Paul Vandevelde
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Temperature Effects ◽  
Test Equipment ◽  
Rate Test

Numerical and Experimental Study of Fire Whirl Generated in 15 × 15 Square Array Fires Placed in Cross Wind

2008 ◽  
Author(s):  
Kohyu Satoh ◽  
Naian Liu ◽  
Qiong Liu ◽  
K. T. Yang
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large City ◽  
Heat Flow Rate ◽  
Fire Whirl ◽  
Square Array

Fire whirls in large city fires and forest fires, which are highly dangerous and destructive, can cause substantial casualties and property damages. It is important to examine under what conditions of weather and geography such merging fires and fire whirls are generated. However, detailed physical characteristics about them are not fully clarified yet. Therefore, we have conducted preliminary studies about merging fires and swirling fires and found that they can enhance the fire spread. If sufficient knowledge can be obtained by relevant experiments and numerical computations, it may be possible to mitigate the damages due to merged fires and fire whirls. The objective of this study is to investigate the swirling conditions of fires in square arrays, applying wind at one corner, in laboratory experiments and also by CFD numerical simulations. Varying the inter-fire distance, heat release rate and mass flow rate by a wind fan, ‘swirling’ or ‘non-swirling’ in the array were judged. It has been found that the fire whirl generation is highly affected by the inter-fire distance in the array, the total heat release rate and also the mass flow rate by a fan. We obtained the conditions of swirling fire generation in 15 × 15 square array for (1) the ratio between the upward mass flow rate vs. applied mass flow rate in the upward swirling plume and (2) a non-dimensional relationship between the heat flow rate in the swirling plume and the applied mass flow rate.

scholarly journals Fire Size of Gasoline Pool Fires

2020 ◽  
Vol 17 (2) ◽  
pp. 411
Author(s):  
Iveta Marková ◽  
Jozef Lauko ◽  
Linda Makovická Osvaldová ◽  
Vladimír Mózer ◽  
Jozef Svetlík ◽  
...  
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Turbulent Flame ◽  
Flame Height ◽  
Pool Fires ◽  
Atmospheric Conditions ◽  
Model Liquid ◽  
Fire Models ◽  
Fire Area

This article presents an experimental investigation of the flame characteristics of the gasoline pool fire. A series of experiments with different pool sizes and mixture contents were conducted to study the combustion behavior of pool fires in atmospheric conditions. The initial pool area of 0.25 m2, 0.66 m2, and 2.8 m2, the initial volume of fuel and time of burning process, and the initial gasoline thickness of 20 mm were determined in each experiment. The fire models are defined by the European standard EN 3 and were used to model fire of the class MB (model liquid fire for the fire area 0.25 m2), of the class 21B (model liquid fire for the fire area 0.66 m2), and 89B (model liquid fire for the fire area 2.8 m2). The fire models were used to class 21B and 89B for fuel by Standard EN 3. The flame geometrical characteristics were recorded by a CCD (charge-coupled device) digital camera. The results show turbulent flame with constant loss burning rate per area, different flame height, and different heat release rate. Regression rate increases linearly with increasing pans diameter. The results show a linear dependence of the HRR (heat release rate) depending on the fire area (average 2.6 times).

Experimental Study on Homogeneous Charge Compression Ignition Combustion With Fuel of Dimethyl Ether and Natural Gas

2005 ◽  
Vol 128 (2) ◽  
pp. 414-420 ◽  
Author(s):  
Mingfa Yao ◽  
Zunqing Zheng ◽  
Jin Qin
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Dimethyl Ether ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Hcci Combustion ◽  
Peak Cylinder Pressure

The homogeneous charge compression ignition (HCCI) combustion fueled by dimethyl ether (DME) and compressed natural gas (CNG) was investigated. The experimental work was carried out on a single-cylinder diesel engine. The results show that adjusting the proportions of DME and CNG is an effective technique for controlling HCCI combustion and extending the HCCI operating range. The combustion process of HCCI with dual fuel is characterized by a distinctive two-stage heat release process. As CNG flow rate increases, the magnitude of peak cylinder pressure and the peak heat release rate in the second stage goes up. As DME flow rate increases, the peak cylinder pressure, heat release rate, and NOx emissions increase while THC and CO emissions decrease.

Study On Design Method of Combustion Reference Values for Model-Based Control of Advanced Diesel Engine

2021 ◽  
Author(s):  
Jihoon Kim ◽  
Yudai Yamasaki
Keyword(s):  
Heat Release ◽  
Control Systems ◽  
Reference Values ◽  
Heat Release Rate ◽  
Release Rate ◽  
Design Method ◽  
Operating Conditions ◽  
Compression Ignition ◽  
Model Based Control ◽  
Model Based

Abstract Model-based control systems are drawing attention in relation to implementing next-generation combustion technologies with high thermal efficiency and low emissions, such as homogeneous charge compression ignition (HCCI) and premixed charge compression ignition (PCCI) combustion, which have low robustness. A model-based control system derives control inputs according to reference values and operating conditions during every cycle, and has potential to replace the conventional control map, which requires a large number of experiments. However, model-based control for engines requires reference values for combustion, such as heat release rate peak timing and heat release rate peak value; such values represent the combustion state. Therefore, the reference for the transient condition is important for utilizing the benefit of model-based control systems, given that such systems derive control outputs cycle by cycle. In this study, design method for the combustion reference values for the transient operating condition is described for advanced diesel combustion, which uses premixed compression ignition combustion shows multiple heat releases. Specifically, a method utilizing future operating conditions in consideration of the driving characteristics is proposed and compared in engine control experiments. The proposed method was evaluated under certain part of worldwide harmonized light vehicles test cycles (WLTC) mode considering real road conditions. Results showed that designing the combustion reference values for transient operation by considering future operating conditions is effective to ensure advanced combustion, and such method has the potential to consider the driving characteristics.

Accuracy of Diesel Engine Combustion Metrics Over the Full Range of Engine Operating Conditions

2018 ◽  
Author(s):  
Peter G. Dowell ◽  
Richard D. Burke ◽  
Sam Akehurst
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Full Range ◽  
Operating Conditions ◽  
Strong Impact ◽  
Combustion Analysis ◽  
Operating Range ◽  
Peak Heat Release Rate ◽  
Holistic Understanding

Measuring and analyzing combustion is a critical part of the development of high efficiency and low emitting engines. Faced with changes in legislation such as Real Driving Emissions and the fundamental change in the role of the combustion engine with the introduction of hybrid-electric powertrains, it is essential that combustion analysis can be conducted accurately across the full range of operating conditions. In this work, the sensitivity of five key combustion metrics is investigated with respect to eight necessary assumptions used for single zone Diesel Combustion analysis. The sensitivity was evaluated over the complete operating range of the engine using a combination of experimental and modelling techniques. This provides a holistic understanding of combustion measurement accuracy. For several metrics, it was found that the sensitivity at the mid speed/load condition was not representative of sensitivity across the full operating range, in particular at low speeds and loads. Peak heat release rate and indicated mean effective pressure were found to be most sensitive to the determination of top dead center (TDC) and the assumption of in-cylinder gas properties. An error of 0.5° in the location of TDC would cause on average a 4.2% error in peak heat release rate. The ratio of specific heats had a strong impact on peak heat release with an error of 8% for using the assumption of a constant value. A novel method for determining TDC was proposed which combined a filling and emptying simulation with measured data obtained experimentally from an advanced engine test rig with external boosting system. This approach improved the robustness of the prediction of TDC which will allow engineers to measure accurate combustion data in operating conditions representative of in-service applications.

Flame Transfer Functions for Liquid-Fueled Swirl-Stabilized Turbulent Lean Direct Fuel Injection Combustion

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Tongxun Yi ◽  
Domenic A. Santavicca
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Fuel Injection ◽  
Transfer Functions ◽  
Fuel Flow Rate ◽  
Modeling And Control ◽  
Fuel Flow ◽  
Direct Fuel Injection

Heat release rate responses to inlet fuel modulations, i.e., the flame transfer function (FTF), are measured for a turbulent, liquid-fueled, swirl-stabilized lean direct fuel injection combustor. Fuel modulations are achieved using a motor-driven rotary fuel valve designed specially for this purpose, which is capable of fuel modulations of up to 1 kHz. Small-amplitude fuel modulations, typically below 2.0% of the mean fuel, are applied in this study. There is almost no change in FTFs at different fuel-modulation amplitudes, implying that the derived FTFs are linear and that the induced heat release rate oscillations mainly respond to variations in the instantaneous fuel flow rate rather than in the droplet size and distribution. The gain and phases of the FTFs at different air flow rates and preheat temperatures are examined. The instantaneous fuel flow rate is determined from pressure measurements upstream of a fuel nozzle. Applications of the FTF to modeling and control of combustion instability and lean blowout are discussed.

Fundamental Study of Diesel-Piloted Natural Gas Direct Injection Under Different Operating Conditions

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Georg Fink ◽  
Michael Jud ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Soot Formation ◽  
Direct Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Gas Jet ◽  
Ignition And Combustion

Natural gas as an alternative fuel in engine applications substantially reduces both pollutant and greenhouse gas emissions. High pressure dual fuel (HPDF) direct injection of natural gas and diesel pilot has the potential to minimize methane slip from gas engines and increase the fuel flexibility, while retaining the high efficiency of a diesel engine. Speed and load variations as well as various strategies for emission reduction entail a wide range of different operating conditions. The influence of these operating conditions on the ignition and combustion process is investigated on a rapid compression expansion machine (RCEM). By combining simultaneous shadowgraphy (SG) and OH* imaging with heat release rate analysis, an improved understanding of the ignition and combustion process is established. At high temperatures and pressures, the reduced pilot ignition delay and lift-off length minimize the effect of natural gas jet entrainment on pilot mixture formation. A simple geometrical constraint was found to reflect the susceptibility for misfiring. At the same time, natural gas ignition is delayed by the early pilot ignition close to the injector tip. The shape of heat release is only marginally affected by the operating conditions and mainly determined by the degree of premixing at the time of gas jet ignition. Luminescence from the sooting natural gas flame is generally only detected after the flame extends across the whole gas jet at peak heat release rate. Termination of gas injection at this time was confirmed to effectively suppress soot formation, while a strongly sooting pilot seems to intensify soot formation within the natural gas jet.

The Effect of Sauter Mean Diameter Fluctuations on the Heat Release Rate in a Lean-Burn Aero-Engine Combustor

2019 ◽  
Author(s):  
Nicholas C. W. Treleaven ◽  
Andrew Garmory ◽  
Gary J. Page
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Release Rate ◽  
Release Rate ◽  
Sauter Mean Diameter ◽  
Lean Burn ◽  
Thermoacoustic Instability ◽  
Mean Diameter

Abstract It has been shown that the fluctuations of pressure caused by a thermoacoustic instability can affect the mass flow rate of air and atomisation of the liquid fuel inside a gas turbine. Tests with premixed flames have confirmed that the fluctuations of the mass flow rate of air can affect the heat release rate through purely aerodynamic phenomenon but little work has been done to test the sensitivity of the heat release rate to changes in the fuel atomisation process. In this study, a lean-burn combustor geometry is supplied with a fuel spray fluctuation of SMD (Sauter mean diameter) of 20% with respect to the mean value and the heat release rate predicted using Large Eddy Simulation (LES) with combustion predicted using a presumed probability density function (PPDF), flamelet generated manifolds (FGM) method. Previous work has shown that at atmospheric conditions the SMD may fluctuate by up to 16% percent and at low frequencies may be reasonably well predicted by using a correlation based on the instantaneous velocity and mass flow rate of air close to the air-blast atomiser. Analysis of the flow fields highlights a complicated spray, flame and wall interaction as being responsible for this observed fluctuation of heat release rate. The heat release rate predicted by the LES shows a 20% fluctuation which implies that even small fluctuations of SMD will significantly contribute to thermoacoustic instabilities.

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