Flame length

Diffusion Flames in the Transition Region. As the velocity of the fuel jet increases in the laminar to turbulent transition region, an instabihty develops at the top of the flame and spreads down to its base. This is caused by the shear forces at the boundaries of the fuel jet. The flame length in the transition region is usually calculated by means of empirical formulas of the form (eq. 13) where I = length of the flame, m r = radius of the fuel jet, m v = fuel flow velocity, m/s and and are empirical constants. 

Explosion venting is always accompanied by flame propagation plus pressure consequences in the surrounding areas. Tne flame length will be larger with a lesser static activation pressure and smaller vent area. Depending on the volume of the protected equipment, it can reach up to 50 m. The pressure effect in the vicinity of the vent area is... 

Referring to Figure 7-72 at the calculated heat release, H., read the flame length, and refer to dimensional diagram for flame plume from a stack. Figure 7-73. 

Figure 7-72. Flame length versus heat release industrial sizes and releases (customary units). Reprinted by permission, American Petroleum Institute, API RP-521, Guide for Pressure Relieving and Depressuring Systems, 3rd Ed., Nov. 1990 [33].

L = height of flame (length of flame from top of stack to flame tip), ft... 

This has been shown to be quite accurate for distances as close to the flame as one flame length [61],... 

This gives flame length for conditions other than maximum flow. 

This assumes that the flame length stays the same for any tvind velocity that is not rigidly true. With a t ind greater than 60 miles/hr, the flame tends to shorten. Straite [62] suggests that practically this can be neglected. 

Liftoff height with jet velocity in free jet [10] (H attached flame length, quenching distance, Hp liftoff height, L premixed flame length). 

Efforts are being made to apply the above method to the horizontal concurrent flame spread. Some problems have been encountered in estimating the horizontal flame length x. since earlier... 

Example 8.1 It is found that flame length on a vertical wall can be approximated as... 

Figure 10.4 Flame length intermittency from Zukoski [8]...

The flame height is intimately related to the entrainment rate. Indeed, one is dependent on the other. For a turbulent flame that can entrain n times the air needed for combustion (Equation (10.34)), and r, the mass stoichiometric oxygen to fuel ratio, the mass rate of fuel reacted over the flame length, Zf, is... 

Figure 10.18 Flame lengths for small Q from Zukoski [25]...

Gross, D., Measurement of flame length under ceilings, Fire Safety J., 1989, 15, 31—44. 

The exposed area of the second item exposed (AF ) depends on the flame length (zf) and its diameter. 

The pyrolysis product gas enters the secondary chamber through a burner that is mounted vertically, enabling flow of the product gas into the combustion chamber, ensuring extended flame length. The treated secondary off gas is scrubbed in a shower and ejected into the atmosphere. 

The effect of wind and tilt on flame geometry has been addressed in the SPFE Handbook (Beyler, 2002). The angle of tilt can be determined from the following equation and used to calculate the vertical and horizontal components of the flame length (see Figure 5-7) ... 

In relatively still air, the flame length, L (m), of most jet flames can be estimated as ... 

To calculate the radiant heat contours for gas or liquid jet fire, approximated multiplying factors have been developed as illustrated in Table 5-4 (Spouge, 1999). The factors do not account for the affects of objects on radiant heat. The multiplying factor for each heat contour is applied to the flame length. 

The ratio of L/D (flame length to the gas exit diameter) is calculated and found to be 139, which is less than 200. Therefore, the jet flame is buoyancy-controlled and the calculated flame length of 13.9 m is appropriate. 

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