Design of a Freely Rotating Wind Tunnel Test Bench for Measurements of Dynamic Coefficients

TL;DR

This paper introduces a novel wind tunnel test bench called MiRo that uses stereovision and a freely-rotating setup to accurately measure aerodynamic stability and damping coefficients of projectiles, improving aerodynamic testing methods.

Contribution

The paper presents a new measurement methodology combining stereovision and a three-axis rotating bench for simultaneous, non-intrusive aerodynamic coefficient determination in wind tunnel tests.

Findings

MiRo provides reliable and repeatable measurements.

The method shows good agreement with traditional measurement techniques.

It enhances the accuracy of aerodynamic coefficient measurements.

Abstract

The needs to improve performances of artillery projectiles require accurate aerodynamic investigation methods. The aerodynamic design of a projectile usually starts from numerical analyses, mostly including semiempirical methods and/or Computational Fluid Dynamics (CFD), up to experimental techniques composed of wind-tunnel measurements or free-flight validations. In the frame, the present paper proposes a dedicated measurement methodology able to simultaneously determine the stability derivative C m$\alpha$ and the pitch damping coefficient sum Cmq + Cm$\alpha$ in a wind tunnel by means of a single and almost non-intrusive metrological setup called MiRo. This method is based on the stereovision principle and a three-axis freely-rotating mechanical test bench. In order to assess the reliability, repeatability and accuracy of this technique, the MiRo wind tunnel measurements are compared to other sources like aerodynamic balance measurements, alternative wind tunnel measurements, Ludwieg tube measurements, free-flight measurements and CFD simulations.