Experimental evaluation of the flow structure in a vertical conical diffuser with different air supply methods

Abstract

RELEVANCE of the study is determined by the fact that vertical conical diffusers are used as auxiliary devices in many technical applications in various industries (chemical industry, power engineering, technological devices, etc.).THE PURPOSE. The influence of the method (design) of air supply, the cross-sectional shape of the supply channels and nozzle tubes on the gas-dynamic structure of the flow in a vertical diffuser for different flow characteristics was assessed.METHODS. The structure (distribution) of the flow inside a vertical diffuser for supplying air using different designs of supply channels was studied on an experimental bench. Based on the thermal imaging method, the flow structure in a vertical diffuser was studied. In this study, two methods of supplying air to a vertical diffuser were studied: supplying air through one straight channel from the bottom and nozzle supplying air through four tubes. The channels and nozzles had cross sections in the shape of a circle, square and triangle. Accordingly, the influence of six air supply designs into a vertical diffuser and their influence on the gas-dynamic flow structure were studied.RESULTS. The experiments were carried out under stationary air flow conditions in the diffuser for air flow rates from 0.015 to 0.06 m3/s. The Reynolds number for the air flow at the outlet of the supply channel was in the range from 42500 to 150000. Thermograms of the flow structure in a vertical diffuser were obtained for different methods of air supply for different flow characteristics.CONCLUSION. Features of the flow structure in a vertical diffuser with traditional air supply from below through one channel consist in the formation of a pronounced central air flow along the vertical axis of the diffuser when using all channel configurations. In this case, the cross-sectional shape of the supply channel has a significant impact on the flow structure in the conical diffuser. Features of the flow structure in a vertical diffuser with nozzle air supply through four tubes are the absence of stagnant zones and a central air flow along the axis. At the same time, the use of square and triangular nozzle tubes leads to a more uniform distribution of air flow throughout the entire volume of the vertical diffuser.