舰载直升机着舰风限图计算

 基于动量源计算流体力学（CFD）方法，建立了一个适合前飞状态舰载直升机着舰风限图计算的新模型。在该模型中，控制方程采用惯性坐标系下的非定常Euler主控方程，空间离散采用有限体积法，时间推进采用5步显式Runge－Kutta迭代，来模拟舰船复杂紊流场环境下直升机着舰过程中的旋翼/机身/舰体耦合气动特性；为显著提高计算效率，使用动量源模型模拟旋翼流场的作用；同时考虑着舰飞行状态下的直升机平衡计算，在此基础上确定风限图。以UH-60为研究对象，选取风向角为0°、60°和300°三种状态进行了直升机的平衡计算，并与得到的试验数据进行对比分析，验证了结合CFD的平衡计算方法的可靠性。应用所建立的方法，以旋翼操纵量、尾桨操纵量、直升机姿态角和全机需用功率为判断标准，给出了算例直升机的着舰风限图。结果表明基于CFD的着舰风限图计算方法可以有效地用于舰载直升机着舰风限图的确定。

Calculation of shipboard helicopter's landing operating envelope by CFD method

In this paper, a new model for calculating shipboard helicopter's landing operating envelope at forward fight condition is established by means of the momentum-source CFD method. In the new model, unsteady Euler equations in inertial coordinate system are used as governing equations, finite volume method (FVM) is employed in spatial discretization, and a five-stage Runge-Kutta explicit time iteration algorithm is adopted in temporal discretization, which all can help well simulate the rotor/fuselage/ship coupled aerodynamic characteristics in a complex turbulent flowfield environment during landing on the ship. To improve efficiency significantly, momentumsource model is chosen to represent the effect of rotor on its flowfield. In addition, the helicopter's trim calculation is also considered determine the operating envelope. Then, a Helicopter UH-60 is selected as the research object, and the wind azimuths of 0, 60 and 300 degrees are chosen for trim calculations. By using the available test data, the capability of the present trim method combined with CFD model is examined. With this method, the sample helicopter's landing operating envelope is calculated based on the judging criteria determined by the main rotor and tail rotor's control, helicopter's attitude angle and required power. Results show that the present method is suitable for determining shipboard helicopter's landing operating envelope.