Effect of pipe geometry and material properties on flow characteristics and thermal performance of a conical Hartmann–Sprenger tube

Abstract

The Hartmann–Sprenger resonance tube is an acoustic device which is the basic part of acoustic igniters with no moving part or electrical spark. In this paper, effects of some design specifications on internal oscillatory flow and thermal performance of a conical Hartmann–Sprenger resonance tube are studied using both experimental and numerical methods. For numerical simulations, an implicit density-based 2D model with second-order upwind scheme is applied. To study the effects of geometrical and material specifications, a set of six different case studies with conical shapes is defined. The conical shape of the tube is selected due to its higher thermal effects and its extreme usage in thermal applications. The parameters to be changed here are pipe material, pipe length, gap distance, and the end wall condition which could be closed or perforated for hot gas extraction. Diagrams of temperature vs.entropy are plotted and compared with each other for all cases in which temperature rise is observed. The results indicated that as the gap distance changes, no oscillatory flow and no sensible temperature rise happens. A tiny hole on the tube end wall reduces the temperature inside the tube, as the shorter tube does. For longer tubes, the frequency of oscillations is proportional to the tube fundamental resonance frequency. Using materials with lower thermal conductivity in the tube wall could produce higher temperatures inside the tube. Here, maximum temperature is achieved in longer closed-end tube with lower thermal conductivity material.