Analysis and experiment of a vessels shell cover in submarine structure

This paper aims to achieve analysis and experiment resuhs that relate to mechanics capability and structural parameter of a special saddle shell of revolution. Theoretically speaking, the saddle shell of revolution consists of a toroidal shell and a spherical shell. The shells simultaneous equations can be solved with harmonious terms. Where, the fundamental equations can be solved by as-ymptotic exponential perturbation method. The equations of special solution can be solved by Hovozhilovs special solution. This new idea is from a study of some existing solutions of the toroidal shell. The resuhs have been proved by compared with some experimental results. The experiments aims to study the effect caused by change of material parameter, or by change of different geometric dimensions of the saddle shell, which include the change of thickness, the change of radius of shell, and the change of ribs. Finally, the accepted product of the saddle shell were reinforced by a toroidal rib has been submitted.

Multi-point Optimization of Recirculation Flow Type Casing Treatment in Centrifugal Compressors

High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. R is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.

Numerical Simulation of Natural Convection in Circular Enclosures with Inner Polygonal Cylinders,with Confirmation by Experimental Results

Numerical computations are performed for the natural convection in circular enclosures with inner polygonal cylinders.The polygon surface and the outer envelope are at constant but different temperatures,A body-fitted coordinate system is used,The coordinate system is generated via simple algebraic equations.The transformed governing equations are discretized on a control volume basis with power-law finite difference scheme.The SIMPLE-like algorithm is used to deal with the linkage between pressure and velocities.The numerical results are compared with the experimental data available in the literature,and the agreement between the numerical and experimental results are very good.