(A) study on a cable suspension and balance system for effective wind tunnel tests

Abstract

The main objective of the present study is to propose a new type of model support in order to reduce the support interference and vibration, which are often problematic in wind tunnel tests. Based on the cable-driven parallel robot (CDPR) formulations, a cable suspension and balance system (CSBS) is developed. The CSBS is designed to serve as both a model support and a balance in wind tunnel tests. In addition, this study suggests two novel methodologies to improve the CSBS performance, one for more accurate motion control and the other for improved load measurement. The motion control correction is implemented by applying a multivariate polynomial function that adjusts motion commands to generate the required response utilizing the measured motion data. For more accurate load measurement, a multi-layer perceptron (MLP) is proposed as a correction function. This MLP is trained to provide corrected three force and three moment components according to the reference balance data. Several motion tests, loading tests, and statistical analyses were carried out before and after the corrections to investigate the effectiveness of newly suggested methodologies. The polynomial correction dramatically reduced differences between the motion command and response, and the MLP learning methodology effectively enhanced the load measurement accuracy of the CSBS. Using both of the suggested corrections, the developed CSBS is equipped with the enhanced motion control and the load measurement performance. Several wind tunnel tests were conducted to examine the reliability of a CSBS as a model support and load measurement system, and test results showed good agreement with reference data for a cylinder model and a NACA0015 airfoil model. Finally, the effectiveness of a CSBS application against an aerodynamic interference and vibration was experimentally demonstrated through comparative wind tunnel tests with a rear sting model support.