Flame edge temperature

In the case of an intensive laminar flame combustion, oxygen penetration to the surface, across the high-temperature reaction zone, is hindered due to the high rate of its reaction in the zone. A thermal decomposition of the polymer may be expected to take place under these conditions. Near the combustion limit, oxygen is able to penetrate the zone near the surface underneath the flame edge. However, its concentration (1-2 %) is insufficient for a profound oxidation of the condensed phase. The probability of oxygen penetration to the surface increases when the flame becomes turbulent and when the condensed phase decomposition products are less volatile... 

For a plasma temperature of 8000 K and N(,= lO Vml, A, is about 0.0006 mm, which is very much smaller than the 1-mm sampler orifice, so ions can pass through easily. Hot gases from the plasma impinge on the edges of the sampler orifice so deposits build up and then reduce its diameter with time. The surrounds of the sampler orifice suffer also from corrosive effects due to bombardment by hot species from the plasma flame. These problems necessitate replacement of the sampler from time to time. 

S-shaped flame temperature response with Damkohler number exhibiting edge propagation characteristics. (From Kim, J. and Kim, J.S., Combust. Theory Model, 10, 21,2006.)... 

In these equations x and y denote independent spatial coordinates T, the temperature Tib, the mass fraction of the species p, the pressure u and v the tangential and the transverse components of the velocity, respectively p, the mass density Wk, the molecular weight of the species W, the mean molecular weight of the mixture R, the universal gas constant A, the thermal conductivity of the mixture Cp, the constant pressure heat capacity of the mixture Cp, the constant pressure heat capacity of the species Wk, the molar rate of production of the k species per unit volume hk, the speciflc enthalpy of the species p the viscosity of the mixture and the diffusion velocity of the A species in the y direction. The free stream tangential and transverse velocities at the edge of the boundaiy layer are given by = ax and Vg = —ay, respectively, where a is the strain rate. The strain rate is a measure of the stretch in the flame due to the imposed flow. The form of the chemical production rates and the diffusion velocities can be found in (7-8). 

Solution A fixed control volume is selected as a cylindrical shape with its bases at the burner and flame tip respectively, as shown in Figure 3.11. The radius of the CV cylinder is just large enough to contain all of the flow and thermal effects of the plume. This is illustrated in Figure 3.11 with the ambient edge of the temperature and velocity distributions included in the CV. 

After all the salt has been added, the flame is raised somewhat, causing the molten material to become more viscous as steam is evolved and bubbles are formed. Finally, at 310°, the reaction proper sets in. After the temperature has been kept at 310°-320° for about five minutes the material becomes more mobile and the reaction is over. The molten material is at once poured in a thin layer on to a thick copper plate the edges of which have been bent slightly upwards. The dark-coloured upper layer consists of the sodium salt of naphthol. After it has cooled, the material is powdered and dissolved in water, the naphthol is precipitated from the solution with concentrated hydrochloric acid, and, after cooling, is extracted... 

Flame-retarded grades are widely used for various computer connectors and circuit board components. Representative applications are edge card connectors, grid arrays and memory modules. Non-flame-retarded grades find use in automotive under-the-hood applications, typically connectors and related parts. As higher temperature soldering techniques become more common in the automotive industry, the use of high-temperature plastics such as PCT is expected to increase. It is also possible to formulate unreinforced PCT with crystallization aids and... 

The inverse of the tunnel experiments discussed is the propagation of a flame across a layer of a liquid fuel that has a low flash point temperature. The stratified conditions discussed previously described the layered fuel vapor-air mixture ratios. Under these conditions the propagation rates were found to be 4-5 times the laminar flame speed. This somewhat increased rate compared to the other analytical results is apparently due to diffusion of air to the flame front behind the parabolic leading edge of the propagating flame [41],... 

Figure 12.5 Calculated mean temperature fields in combustors with a set of similar open-edge V-gutter flame holders of height H = 3 cm and apex angle of 60°. The isoterms divide the entire temperature interval from the initial temperature To to combustion temperature Tc into 10 uniform parts and correspond to t = 27.5 ms. The combustor is 1 m long and the distance between the planes of flame holders is 0.05 m. Flame holders are shifted in longitudinal direction by OH (no shift) (a), IH (6), 2H (c), 3H (d), and 5H (e). Combustion of stoichiometric methane-air mixture at the mean inlet velocity Ui = 20 m/s, po = 0.1 MPa, To = 293 K, ko = 0.24 J/kg, /o = 4 mm. The lower and upper boundaries of the computational domain are the symmetry planes...

A two-component phase Doppler interferometer (PDI) was used to determine droplet size, velocity, and number density in spray flames. The data rates were determined according to the procedure discussed in [5]. Statistical properties of the spray at every measurement point were determined from 10,000 validated samples. In regions of the spray where the droplet number density was too small, a sampling time of several minutes was used to determine the spray statistical characteristics. Results were repeatable to within a 5% margin for mean droplet size and velocity. Measurements were carried out with the PDI from the spray centerline to the edge of the spray, in increments of 1.27 mm at an axial position (z) of 10 mm downstream from the nozzle, and increments of 2.54 mm at z = 15 mm, 20, 25, 30, 35, 40, 50, and 60 mm using steam, normal-temperature air, and preheated air as the atomization gas. 

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