Sound propagation i gas-filled capillary-tube-type orous media was investigated. The capillary tubes were taken to be nominally straight with very small pores in the walls of the capillary tubes. The complex wave number and the characteristic mpedance of such media were evaluated. Application to ceramic samples having capillary pores with square cross sections and porous walls is developed as a...

In this paper, a mathematical model of leakage sound propagation through a heat exchanger tubes array in boilers is established, which is based on the Twersky’s sound scattering theory, transmission grating diffraction theory, Fabry-Perot’s interference principle, and algebraic iteration method. The tubes array is made up of large number periodically arranged tubes immersed in air. Its acoustic...

A preliminary study of the feasibility of using piezo-transducer arrays, for detecting flaws in flat aluminum plates and steel tubing, is being performed at The University of Tennessee. The sensor arrays are designed for embedding in aluminum plates and brass tubes. Various forms of defects are placed on the test specimens. Preliminary experiments are carried out using both flat aluminum plate ...

In a multi-cylinder type liquid piston Stirling engine (MCLPSE), columns in U-shaped tubes play the role of solid pistons mechanical engine. Besides straightforward structure, advantages MCLPSE are relatively low operation temperature difference below 100 K and use harmless working fluids air water. This study presents mass spring model for MCLPSE, from which we determine geometrical parameters...

Sound generation by confined stationary jets is of interest to the study of voice and speech production, among other applications. The generation of sound by low Mach number, confined, stationary circular jets was investigated. Experiments were performed using a quiet flow supply, muffler-terminated rigid uniform tubes, and acrylic orifice plates. A spectral decomposition method based on a line...

This paper studies the acoustic backscattering of short ultrasonic pulses by air-filled stainless steel-solid polymer two-layer cylindrical tubes immersed in water. The stainless steel one-layer tube is taken as a reference. The focus of this paper is on revealing the effects of physical characteristics of the solid polymer on the scattering phenomenon. The work is done from the calculation of ...

This paper investigates the mechanical erosion of the metal tubes in bagasse-fired boilers with the aid of the acoustic emission technique. By studying the material removal under various collision conditions, the paper analyzes the dependence of the erosion wear upon the impact angle, velocity, size and concentration of the particles. It was found that the material removal mechanisms were mainl...

Thermoacoustic instabilities can arise in systems where unsteady heat release is favorably coupled with acoustic pressure oscillations. A modified Rijke tube with segments having different sections is found to have lower threshold levels of heat addition rate needed for exciting the fundamental acoustic mode of the tube. Experiments indicate that about 115 W of heating power is required to prod...