Stepanova N. Hydrodynamics of self-boiling flows in canals of heat technological systems

Dissertation is dedicated to studying the hydrodynamic processes in drainage canals elements of heat technical systems, where water begins motion in the saturation state or being under heated till saturation temperature with the following critical or pre- critical two phase flow. The influence of configuration on passing ability of the canal with self-boiling flow was analyzed. The losses of heat due to friction in local supports was studied, and the mu-tual influence of local supports during pre- critical and critical two phase movement. The general tendencies of volume gas influence on the coefficient in hydraulic friction and lo-cal resistance were calculated. The mathematical model of heat hydraulic processes in drainage canal of compli-cated configuration, built on the basis of equations of dependencies for estimating critical parameters and obtaining the dependencies of hydraulic friction and local resistance dur-ing two phase flow. The given mathematical model accounts the geometrical peculiarities of the canal, the initial dynamical flow parameters, the presence of heat exchange with the environment and peculiarities of phase sliding in the canal. Critical parameters of self- boiling flows are evaluated by two methods: using the notion of weak motion speed in two phase flow; according to invariability of mass loss of self-boiling flow with anti pressure decrease. For the modeling of critical flows in drainage canals, the preference is given to the second method. On the basis of the model proposed the methodology of pre-critical and critical self-boiling flows in heat technological system drainage canals was worked out. Key words: self-boiling flow, drainage canal, two phase flow, pre-critical, critical flows, pressure loss, local supports, mutual influence, hydraulic friction coefficient, canal passing capability.