A Quantitative Evaluation Method for Impeller-Volute Tongue Interaction and Application to Squirrel Cage Fan With Bionic Volute Tongue

Abstract

The impeller–volute tongue interaction strongly influences the aerodynamic performance of squirrel cage fan. To quantitatively evaluate the level of impeller–volute tongue interaction, we propose two parameters, i.e., recirculated flow coefficient and reversed flow coefficient based on a careful inspection of flow pattern near the volute tongue of a squirrel cage fan. Inspired by the good aerodynamic characteristics of owl wing, particular effort is made to develop a bionic design of volute tongue to improve the impeller–volute tongue match. The aerodynamic performances of both the squirrel cage fans with original volute tongue (OVT) and bionic volute tongue (BVT) are numerically and experimentally analyzed. The results show that, by employing the bionic design of volute tongue, the squirrel cage fan can achieve higher aerodynamic performance than that with OVT. Better match between impeller and volute tongue is obtained with smaller recirculated flow coefficient and reversed flow coefficient, validating the effectiveness of the proposed parameters to quantitatively evaluate the level of impeller–volute tongue interaction. In addition, the bionic design of volute tongue is beneficial for the improvement of flow quality and for the relief of abrupt pressure variation and axial nonuniformity of flow near the volute tongue. This work is helpful for a deep understanding of complex flow pattern in squirrel cage fan.