Flame properties

The counterflow configuration has been extensively utilized to provide benchmark experimental data for the study of stretched flame phenomena and the modeling of turbulent flames through the concept of laminar flamelets. Global flame properties of a fuel/oxidizer mixture obtained using this configuration, such as laminar flame speed and extinction stretch rate, have also been widely used as target responses for the development, validation, and optimization of a detailed reaction mechanism. In particular, extinction stretch rate represents a kinetics-affected phenomenon and characterizes the interaction between a characteristic flame time and a characteristic flow time. Furthermore, the study of extinction phenomena is of fundamental and practical importance in the field of combustion, and is closely related to the areas of safety, fire suppression, and control of combustion processes. 

The slow, thermal decomposition of hydrazoic acid in a static system has been studied by Meyer and Schumacher58. It turned out to be completely governed by heterogeneous catalysis. There are no studies on the kinetics of the homogeneous decomposition of this substance save for the investigation of its decomposition flame59. From the variation of flame properties with pressure it can be deduced that second-order reactions control the over-all rate. The unimolecular reaction... 

These instantaneous temperature and velocity values can be related to values of the average fluctuating mass flux

for our experimental conditions, utilizing assumptions of the ideal gas law and fast flame chemistry. Here p and u are fluctuation values of density and velocity, respectively, Knowledge of flame properties such as p u > provides key data needed for developing improved combustion models. 

Zhang, J., Jiang, D. D., and Wilkie, C. A. Thermal and flame properties of polyethylene and polypropylene nanocomposites based on an oligomerically-modified clay, Polym. Degrad. Stab. (2006), 91, 298-304. 

Thermal and Flame Properties of Polymer Composites with Clay and CNTs... 

The second approach to the interpretation of flame profiles is to assume a reaction mechanism and data, solve the conservation equations to obtain the flame properties, and then compare these with experiment. 

Heat transfer occurs as long as there is a temperature gradient, and heat release as required by a combustion reaction guarantees a temperature gradient. The heat transfer process controls the stability of the flame. It is responsible for ignition, extinction, and other flame properties. Heat transfer is responsible for flame temperature distribution, and ultimately it is responsible for delivering the energy to the process of interest. Because of its importance and its relevance to the topic of discussion, heat transfer is addressed in detail in Section 4.3. 

Combustion safeguard — A safety control directly responsive to flame properties it senses the presence and/or absence of flame and correspondingly deenergizes the fuel (and oxygen) safety valves in the event of flame failure within 4 seconds of the loss of the flame signal. 

High-Temperature Hydrolysis of AlCl, in Hydrogen Flame Properties y-form, larger particles with admixture of cubic phase in the surface layer, particle size 10-50 nm, specihc surface area 144 m-/g [1087]. 

The CARS measurements can be used for fhe evaluation of CFD codes [86-90], buf fhey can also be used to gain an insighf info fhe combustion and flow in the near burner region. Hughes et al. [91] uses a similar CARS optical arrangement to make temperature measurements in two natural gas flames. One of the burners produces a high temperature jet-like flame. The other has tertiary air supplied off the central axis on either side of the flame jet. Details of fhe burners can be found with Hughes et al. [91]. For these burners, the CARS temperature was measured at several axial and radial locations to establish the flame properties. 

For the detailed characterization of flame properties, a motorized arm is located on the right-hand side of the furnace as shown in Figure 27.12. This arm allows a sampling probe (connected to a second set of gas analyzers)... 

This work has emphasized the major flame properties including the flame speed, temperature and major species spatial profiles, and the post-flame NO concentration. These measurements and calculations are performed on stationary free flames. 

Another reaction with a significant effect on the flame properties is... 

Atomic Absorption Spectrometry (AAS) and Atomic Emission Spectrometry (AES) 443 Table 12.2 Typical gas mixtures and flame properties for flame-AAS. 

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