Study on the Size Distribution and Similarity Law of Bubble Nuclei in Water

To study the distribution characteristics and similarity laws of nuclei under different pressures,based on the selfdesigned decompression chamber and the acoustic measuring system,the size distributions of nuclei in the degassed tap water under negative ambient pressures were measured.A number density distribution function of nuclei based on the modified Weibull distribution function was proposed and verified by the experimental measurement results and some published data of nuclei size distribution.Based on this nuclei number density distribution function,the similarity law of the nuclei size distribution was analyzed:in the scale experiment,the value of exponential in the similarity law of the nuclei number density should be determined by the nuclei size distribution of the water in the prototype experiment and the actual nuclei size distribution of the water in the model experiment.And a precondition is that the nuclei size distributions are similar.

Study of Similarity Law for Bird Impact on Structure

With dimensional analysis and similarity theory, the model similarity law of aircraft structures trader bird impact load is investigated. Numerical calculations by means of nonlinear dynamic software ANSYS/LS-DYNA are conducted on the finite element models constructed with different scaling factors. The influence of strain rate on the model similarity law is found to be dependent on the strain rate sensitivity of materials and scale factors. Specifically, materials that are not sensitive to strain rate obey the model similarity law in the bird impact process. The conclusions obtained are supposed to provide a theoretical basis for the experimental work of bird impact on aircraft structure.

STUDY ON SIMILARITY LAWS OF A DISTORTED RIVER MODEL WITH A MOVABLE BED

WT5”BZ]In this study, by considering the scale ratio related to the specific gravity of the submerged bed material, and introducing a degree of distortion, n the similarity laws for a distorted river model with a movable bed were derived under the conditions that the values of dual dimensionless parameters in a regime-criterion diagram for the bars are the same in a model as they are in a prototype, and that a resistance law such as the Manning-Strickler-type formula is to be valid for a model and a prototype. The usefulness of the similarity laws derived in this study was verified by comparing the bed forms from the distroted model experiments with the bed forms from the 1/50-scale undistorted model experiments, which were performed by the Hokkaido Development Bureau (H. D. B.), Japan, to examine the tentative plan for the improvement of a low-flow channel in the Chubetsu River, which is a tributary of the Ishikari River. It is considered that the distorted model experiments to be valid with either sand or lightweight bed material. [WT5”HZ]

Three-Dimensional Shaking Table Test of 1/10 Scale Model of Reinforced Concrete Frame Structure

A l/10 scale model of reinforced concrete (R C ) frame structure was tested on the 15t-shaking table of State Key Laboratory, Tongji University The structural prototype was a 10-storey office building that was damaged in the 1985 Mexico major earthquake[1] The original acceleration records in the earthquake were applied as the input waves in the test The dynamical test model was designed according to the general law of similarity, and the effect of the shortage of artificial quality was considered The model was carefully made of fine gravel concrete and galvanized iron wire The damage of test model is in good agreement with that of archetypal building in the experiment