Reconciling wind tunnel data with real performance: influence of freestream turbulence intensity and large-scale unsteadiness

风洞数据与实际性能的协调：自由流湍流强度和大规模不定常的影响

• 批准号: 2889141
• 金额: --
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2889141
• 关键词: Reconciling; wind; tunnel; data; real

Our current inability to reconcile test data with actual performance of land, sea, and air vehicles, especially under the unsteady conditions which they often encounter in the real world represents a major barrier in improving designs for the energy efficiency of large platforms. Many forms of transportation vehicles face unsteady or turbulent scenarios and without the understanding of what effects this has on the vehicle, there is no way of confidently improving the vehicles design and its efficiency. Prior to the development of CFD tools, model test data pertaining to vehicle performance and their flow fields was almost always acquired in wind-tunnels (or water-tunnels) with various technical methods used to acquire physical measurements. Typically, these flow facilities incorporated carefully designed flow conditioning devices to ensure that the vehicle model was subjected to steady uniform flow conditions with a purposely low free-stream turbulence (FST) intensity. These FST levels can then be deliberately increased using passive or active grids or a combination of the two.The role that FST, defined by both intensity and length scales (e.g. integral, Taylor, Kolmogorov), plays on boundary layer flows, particularly transition-to-turbulence, is still not fully understood. For example, even in the simplest case of flow over a smooth flat plate, the role that the FST intensity and integral length scale directly plays on boundary layer transitions has only recently been characterised. Beyond this canonical case, the role of FST and, indeed inflow unsteadiness in general on applied aero- and hydrodynamic applications requires further investigation. With the rapid growth and development of additive manufacturing, the research community now has at its disposal the ability to rapidly create prototypes and therefore rapidly test different flow conditioning devices with various intricate geometries far being simple screens and grids. This can create conditions, whether steady or unsteady, within a wind tunnel at lower cost and more rapidly than with conventional fabrication technologies.This project leverages pre-existing physical infrastructure in addition to new equipment designed for the specifics of the problems researched. The project will facilitate the design, build and test of a wind-tunnel flow conditioning device, specifically to elevate the turbulence intensity in addition to being able to induce a level of shear flow. This will lead to 'extreme' testing of various bluff-body vehicles on test models representative of land, sea and air vehicles. This data will then serve as computational fluid dynamics (CFD) validation cases and will allow insight gains leading to improved empirical models and improved platform designs. The initial premise of this project is to use a simplistic bluff body model such as the Ahmed body to conduct high-fidelity flow and performance measurements on. Once this testing has been conducted the project will move onto more complex geometries.

我们目前无法将测试数据与土地，海洋和空中车辆的实际性能调和，尤其是在他们在现实世界中经常遇到的不稳定条件下，这是改善大型平台能源效率设计的主要障碍。许多形式的运输车辆面临着不稳定或动荡的场景，并且没有了解这对车辆的影响，因此无法自信地改善车辆的设计及其效率。在开发CFD工具之前，与车辆性能及其流场有关的模型测试数据几乎总是以风核（或水刺）的形式获得，并使用用于获取物理测量的各种技术方法。通常，这些流动设施合并了精心设计的流动调节装置，以确保车辆模型具有稳定的均匀流动条件，并有目的地自由流湍流（FST）强度。然后，可以使用被动或主动网格或两者的组合故意提高这些FST水平。由强度和长度尺度定义的FST（例如Integral，Taylor，Kolmogorov）在边界层流中扮演，尤其是过渡到扰动的作用，尚未完全理解。例如，即使在平滑平板上流过的最简单的情况下，FST强度和积分长度尺度直接在边界层跃迁上扮演的角色才被最近表征。除了这种规范的情况外，FST的作用以及总体上不稳定在应用的空气和水动力应用中的作用还需要进一步研究。随着添加剂制造的快速增长和开发，研究界现在具有快速创建原型的能力，因此可以快速测试具有各种复杂几何形状的不同流条件设备，这是简单的屏幕和网格。这可以在风洞内以较低的成本和传统制造技术更快的速度创造条件，无论是稳定的还是不稳定的。除了针对研究的问题的具体细节外，该项目利用了预先存在的物理基础设施的预先存在的物理基础设施。该项目将促进风能隧道流量调节装置的设计，构建和测试，特别是为了提高湍流强度，除了能够诱导一定程度的剪切流。这将导致对代表土地，海洋和空中车辆的测试模型上各种虚张声势车辆的“极端”测试。然后，这些数据将用作计算流体动力学（CFD）验证案例，并允许洞察力获得，从而改善经验模型和改进的平台设计。该项目的最初前提是使用诸如艾哈迈德身体等简单的虚张声势身体模型来进行高保真流程和绩效测量。一旦进行了测试，该项目将转移到更复杂的几何形状上。