Purpose

This paper aims to propose a dedicated measurement methodology able to simultaneously determine the stability derivative C_mα̇ and the pitch damping coefficient sum C_mq + C_mα̇ in a wind tunnel using a single and almost non-intrusive metrological setup called MiRo.

Design/methodology/approach

To assess the MiRo method’s reliability, repeatability and accuracy, the measurements obtained with this technique are compared to other sources like aerodynamic balance measurements, alternative wind tunnel measurements, Ludwieg tube measurements, free-flight measurements and computational fluid dynamics (CFD) simulations. Two different numerical approaches are compared and used to validate the MiRo method. The first numerical method forces the projectile to describe a pure oscillation motion with small amplitude along the pitch axis during a rectilinear flight, whereas the second numerical approach couples the one degrees of freedom simulation motion equations with CFD methods.

Findings

MiRo, a novel and almost non-intrusive technique for dynamic wind tunnel measurements, has been validated by comparison with five other experimental and numerical methodologies. Despite two completely different approaches, both numerical methods give almost identical results and show that the holding system has nearly no impact on the dynamic aerodynamic coefficients. Therefore, it could be assessed that the attitude of MiRo model in the wind tunnel is very close to the free-flight one.

Originality/value

The MiRo method allows studying the attitude of a projectile in a wind tunnel with the least possible impact on the flow around a model.

中文翻译：

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使用自由旋转试验台进行动态空气动力系数的风洞测量

目的

本文旨在提出一种专用测量方法，该方法能够使用称为 MiRo 的单一且几乎非侵入式计量装置在风洞中同时确定稳定性导数C _mα̇和俯仰阻尼系数总和C _mq + C _{mα̇ 。}

设计/方法/途径

为了评估 MiRo 方法的可靠性、可重复性和准确性，将使用该技术获得的测量结果与其他来源（如空气动力学平衡测量、替代风洞测量、路德维格管测量、自由飞行测量和计算流体动力学 (CFD) 模拟）进行比较。比较了两种不同的数值方法，并使用它们来验证 MiRo 方法。第一种数值方法迫使弹丸在直线飞行期间沿俯仰轴描述小振幅的纯振荡运动，而第二种数值方法将单自由度模拟运动方程与 CFD 方法耦合。

发现

MiRo 是一种新颖且几乎非侵入式的动态风洞测量技术，已通过与其他五种实验和数值方法的比较得到验证。尽管采用了两种完全不同的方法，但两种数值方法都给出了几乎相同的结果，并表明固定系统对动态空气动力系数几乎没有影响。因此，可以评估MiRo模型在风洞中的姿态与自由飞行非常接近。

原创性/价值

MiRo 方法允许在风洞中研究射弹的姿态，同时尽可能减少对模型周围流动的影响。