Abstract
For a high speed or large-sized ships, the pressure and temperature of main boiler's steam are going up. Therefore, it needs to study the permissible limit of heat flux for the natural circulation boiler.
By the way, as you know, the hydrodynamic instability in natural circulation boiler will occur under some conditions. We imagine that the hydrodynamic instability prescribes the permissible limit of heat flux for the boiler. Consequently, we perform the experiments and theoretical analysis to get informations about the condition of the flow oscillations.
Our analytical model is based on Terano's linear approximation which treats of the dynamic behavior of a one-through boiler. We extended his method to the small perturbation of pressure drop of two phase flow. The mathematical representation of the pressure drop is shown in this report and we discuss about some author's frictional coefficient concerning to the threshold of instability for a boiling channel.
Then, we show there are two analytical results about parallel boiling channels, one is from loop instability and the other is from parallel channel instability respectively. In all case, the threshold of instability for parallel channels is lower than that of the loop.
