Effect of aspect ratio variation on subsonic aerodynamics of cascade type grid fin at different gap-to-chord ratios

Abstract

This paper dwells upon investigating the effect of aspect ratio (AR) variation on the aerodynamic performance of unconventional control surfaces called grid fins by virtue of a series of subsonic experiments on a simplified grid fin variant called the cascade fin. Wind tunnel tests were performed for different AR (variable span) grid fins. The same had been investigated for different gap-to-chord ratio (g/c) variants. Results demonstrated a tangible increase in the aerodynamic efficiency as well as stall angle reduction for higher AR. Moreover, higher AR leads to increased pitching moment, which emphasizes elevated hinge moment requirements. The study ensued the presence of higher deviation between the low AR fins, that is $AR<2$ compared to the pertinent deviations between the high AR fins, that is $AR\geq2$ . The effect associated with these variations was termed as span effect in this paper. It was established that, the deviations arising due to this phenomena were lesser for higher g/c and higher AR. The analysis of AR variation for different g/c presented a limiting value of AR reduction for stall performance enhancement. Thus, optimised selection of the g/c and AR values can lead to enhanced aerodynamic efficiency alongside an improved stalling characteristic.

Improved Particle Swarm Optimization-Extreme Learning Machine Modeling Strategies for the Accurate Lithium-ion Battery State of Health Estimation and High-adaptability Remaining Useful Life Prediction

“…[33][34][35][36] The virtues of AR are low computational effort and low complexity, but the demerits are that the accuracy of the outcomes decreases over time. 37 The drawbacks of NN are that vast amounts of comprehensive sample data are requested. 38 The battery side reactions will contribute to the performance degradation of the battery, 39 which is macroscopically manifested as capacity decline and internal resistance enhancement, thus degrading the lifetime of the battery.…”