Analyse:Jem/Fragment 048 01

Typus: Verschleierung

Bearbeiter: Graf Isolan

Gesichtet

Untersuchte Arbeit:
Seite: 48, Zeilen: 1-2, Figure 3.6, 5-11

Quelle: Kollar et al 2005
Seite(n): 73-74, Zeilen: 73:24, Fig. 2; 74:1-4.6-7.12-16

[The non-dimensional impact parameter is calculated as]

        B
        =
        
            2
            b
          
              d
              1
            
            +
            
              d
              2
            
        =
        sin
        ⁡
        θ
      
    {\displaystyle 
B=\frac{2b}{d_1+d_2}= \sin \theta
}
  
(3.22)

where d1 is the diameter of the larger droplet and θ is the angle between the line of centers of the droplets at the moment of impact and the relative velocity vector.
[Figure 3.6: Illustration of the definition of geometric parameters of the droplet collision.]
The droplet size ratio is given by

        γ
        =
        
            d
            1
          
            d
            2
          
    {\displaystyle 
\gamma = \frac{d_1}{d_2}\quad
}
  
 (3.23)
The possible outcomes of collisions are illustrated in Figure 3.7. Droplet bounce will occur if there is not enough time for the gas trapped between the droplets to escape and the surfaces of the droplets do not make contact due to the intervening gas film. When the relative velocity of the droplets is higher and the collisional kinetic energy is sufficient to expel [the intervening layer of gas, the droplets will coalesce.]

[page 73]
The non-dimensional impact parameter is calculated as follows:
[Fig. 2. Illustration of the definition of impact parameter b.]
[Page 74]

        B
        =
        
            2
            b
          
              D
              L
            
            +
            
              D
              S
            
    {\displaystyle 
B=\frac{2b}{D_L+D_S} \quad
}
  
(3)
where DL is the diameter of the larger droplet.
(iii) The droplet size ratio is given by

        Δ
        =
        
            D
            S
          
            D
            L
          
        .
        
    {\displaystyle \Delta = \frac{D_S}{D_L}. \quad
}
  
 (4)
It should be clear that 
  
        Δ
        ≤
        1
        ,
      
    {\displaystyle \Delta \le 1,}
  
 although some authors prefer to use the reciprocal 
  
        γ
        =
        
          1
          Δ
        
        .
      
    {\displaystyle \gamma = \frac{1}{\Delta}.}
  
[...] 
When two droplets interact during flight, five distinct regimes of outcomes may occur, as listed in Section 1, and depicted in Fig. 3 in the B–We plane for four different values of Δ. [...] If the relative velocity of the droplets is higher, there is not enough
time for the gas to escape and the surfaces of the droplets do not make contact due to the intervening gas film, so the droplets become deformed and bounce apart. The corresponding domain in Fig. 3 is regime II. When the relative velocity is even higher and the collisional kinetic energy is sufficient to expel the intervening layer of gas, the droplets will coalesce after substantial deformation.