Pressure drop due to acceleration and collisions of particles

The pressure drop due to acceleration and collisions of the particles on the walls and between them, -Apacp, can be calculated with Eq. (4.12) according to the data 

The local resistance coefficient IC ) is calculated for a total of 490 sets of measured data, and the results are given in Fig. 4.5. 

It is clear from Fig. 4.5 that the data for ,c p are considerably concentrated over 85% of the values are in the range 4.3 to 6.2, and the average value is 5.34. This fact indicates that ,c p can be considered to remain essentially constant and that, consequentially, Eq. (4.11) describes well the pressure drop behavior due to the acceleration and collisions of the particles. Therefore the combined consideration of the two kinds of collisions, i.e., the collisions of particles on the wall and between particles, is reasonable and feasible. It should be noted that, as described by Eqs. (4.5) and (4.6), for a given impinging velocity u0, the velocity of particles at the outlet of the accelerating tube depends on the length of the tube Lac, the particles to gas mass flow rate ratio and the mean diameter of particles dv. Therefore Eq. (4.11) actually 

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