Many Small Unmanned Aerial Vehicles (SUAV) are driven by small scale, fixed blade propellers. Flow produced by the propeller can have a significant impact on the aerodynamics of a SUAV. Therefore, in Computational Fluid Dynamic (CFD) simulations, it is often necessary to simulate the SUAV and propeller coupled together. For computational efficiency, the propeller can be modeled in a steady-state view by using momentum source terms to add the thrust and swirl produced by the propeller to the flow field. Many momentum source term models are based on blade element theory. Blade element theory divides the blade into element sections in the spanwise direction and assumes each element to operate independently as a two-dimensional (2D) airfoil. Blade Element Momentum Theory (BEMT) for two small scale propellers are compared to high-fidelity, time-dependent 3D Reynolds Averaged Navier-Stokes (RANS) CFD simulations to determine the accuracy of approximating the complicated 3D flow associated with small scale propellers. Results show that BEMT acceptably predicts thrust when the propeller operates with little separation and the blade has a high aspect ratio with little or no chord variation. However, in large regions of separated flow and blades of lower aspect ratio and chord variation, the accuracy of BEMT diminishes. A secondary goal of this work is to create a basis for developing a more accurate steady-state surrogate model for the momentum imparted to the flow based on high-fidelity, time-dependent, 3D RANS CFD propeller blade simulations. An overview of this surrogate modeling process is briefly discussed.
展开▼
机译：许多小型无人驾驶车辆（SUAV）由小规模，固定刀片螺旋桨驱动。由螺旋桨产生的流动可能对苏瓦的空气动力产生显着影响。因此，在计算流体动态（CFD）模拟中，通常需要模拟苏瓦和螺旋桨耦合在一起。为了计算效率，螺旋桨可以通过使用动量源术语在稳态视图中建模，以将由螺旋桨产生的推力和旋流加到流场中。许多动量源术语模型基于刀片元素理论。叶片元件理论将刀片分成翼叶方向的元件部分，并假定每个元件以独立地操作，作为二维（2D）翼型。两种小型螺旋桨的刀片元素动量理论（BEMT）与高保真，时间依赖3D雷诺平均捕获量（RAN）CFD模拟，以确定近似与小尺度螺旋桨相关的复杂的3D流程的准确性。结果表明，当螺旋桨用几乎没有分离时，BEMT可接受地预测推力，并且刀片具有很少或没有弦变化的高纵横比。然而，在具有较低纵横比和弦变化的分离流和叶片的大区域中，BEMT的准确性减小。这项工作的次要目的是为开发更准确的稳态代理模型，为基于高保真，时间依赖，3D RAN CFD螺旋桨刀片模拟来开发更准确的稳态替代模型。简要讨论了此代理建模过程的概述。
展开▼
