NSWC/WOL TR 76-155 



Inserting the values for the water density and adiabatic exponent, 

 equation B7 becomes 



_ A 



T = 29.7— =S— milliseconds (B7a) 



n /^ 



where A is in inches and p is pounds per square inch. 



Maximum and Minimum Radius, and Period of Oscillation . 

 With increasing amplitude the period increases; the ratio of the 

 periods, T/T, is plotted as a function of the maximum radius AMAX 

 in Figure Bl. The same figure also shows the minimum radius AMIN 

 plotted as a function AMAX. Both curves were calculated by the 

 method given in Appendix A. 



Some Details of the Computation . Consider the computation 

 shown in Figure 2.3.2. We will assume that the pressure signature 

 begins with a shock front followed by an approximately exponential 

 decay. To get the average outside pressure for the first half-period 

 of the motion we estimate the period of oscillation by 



T =cxx T* (B8) 



where T* is the equilibrium period calculated using the pressure 

 value at the start of the motion (i.e., the Shockwave peak pressure + 

 initial ambient) and oc is an arbitrary constant. (For the present 

 computations an ©(-value of 1.25 was used for the first half-cycle 

 of oscillation.) 



The parameter T* is calculated from Equation B7 using a corresponding 

 A* calculated from Equation B6 . The starting point is the initial 

 bubble or bladder radius A. which was estimated from experimentally 

 measured values. For the present calculations the ratio (A. ) /L 



B-3 



