SELF-SIMILAR COMPRESSION OF IDEAL-GAS BY A DISK, CYLINDRICAL OR SPHERICAL PISTON

The compression of ideal (nonviscous and non-heat-conducting) gas by a disk, cylindrical, or spherical piston is treated. The flows being in vestigated are described by known self-similar solutions, including th e solution with a shock wave, ''reflected'' from the plane, axis, or c enter of symmetry, which stops the motion of gas compressed by the pis ton. The comparison of several methods of unrestricted cumulation made in [1] has revealed that the unrestricted cumulation with reflected s hock wave, as regards its energy characteristics, is second only to th e ''non-self-similar'' unrestricted cumulation with isentropic compres sion also from rest to rest. As the adiabatic exponent gamma increases and transition is made from the plane case to cylindrical and from cy lindrical to spherical, the advantages of the isentropic unrestricted cumulation become less obvious. The results given below for the finite degrees of compression (rho degrees denotes the density ratio rho(f)/ rho(0) of compressed, rho(f), and uncompressed, rho(0), gas) reveal th is tendency even more clearly. Along with the energy characteristics, the time of self-similar compression is determined that is obviously l ess than the time required under conditions of the fastest isentropic compression. The calculations are performed for different values of ga mma in a wide range of degrees of compression.