The Effect of Water Quality Characteristics on Cavitation Noise
This study investigated the effects of seawater on cavitation noise using a water jet test, a two-dimensional wing test, and a three-dimensional wing test. A model propeller cavitation test was conducted in a cavitation tunnel using seawater, in order to determine the effects of propeller cavitation more precisely. In the cavitation tests, measured propeller performance for both cavitation noise inception and desinence, as well as the cavitation noise spectrum (see, for example, figure 7). On the basis of the results of the present propeller cavitation test and tests that were carried out previously, we discuss how to control the water quality in the cavitation tunnel to reproduce the cavitation phenomena, especially cavitation noise, in seawater (see, for example, figure 9).
Effect of Surface Material on the Cavitation Erosion Noise: Experimental Investigation
Cavitation includes the occurrence, growth and collapse of vapor bubbles in a liquid. Cavitation noise is the sound uttered during the cavitation progress, and it is mainly induced by the collapse of the bubbles. Under certain presuppositions, the micro-jet and micro-shockwave can be produced when the bubbles collapse. The impact of the microjet and micro-shockwave on the surface of material is strong enough to damage the structure of the material and finally erosion takes place. Accordingly, compared with cavitation, the sound emitted during the cavitation erosion progress has a more source that is induced by the vibration of the solid surface when it is attacked by the micro-jet. In this work, the effect of the surface material on the cavitation erosion noise has been studied. Spectrum characteristics obtained for different metal materials: stainless steel, aluminum bronze, bronze, brass (in the same experimental conditions) has also been presented in this paper. The purpose is to validate the contributions of the impact noise to the cavitation noise.
Exploring interculturally competent teaching in social sciences classrooms
Abstract This paper explores a grounded research-based framework for intercultural competence and discusses the implications of interculturally competent teaching in the classroom and beyond. Given the importance of teachers being interculturally competent in today’s diverse classrooms, a number of questions, based on the framework, are presented, which guide teachers in reflecting upon their own teaching practice and the ways in which they integrate aspects of intercultural competence into their classrooms. The paper also provides some examples from the USA of ways in which intercultural competence development is being addressed in teacher training.