基于推力数值计算的喷水推进船快速性预报与验证

为实现对喷水推进船航速的快速、精准预报,基于ANSYS-CFX软件平台建立喷水推进器推力的计算流体力学(CFD)模型,采用分块六面体结构化网格离散计算域,采用稳态多参考系法求解雷诺时均的Navier-Stokes方程和SST湍流模型,对喷水推进器内的流场进行数值模拟.采用壁面积分法获取喷水推进器的等转速推力曲线,将其与船阻力曲线相叠加,通过求曲线的交点预报航速.选取可提供推进特性图谱的船A、带双级轴流式喷水推进器的船B和带混流式喷水推进器的船C为例,验证该方法的准确性.结果表明:船A配置的喷水推进器的推力计算值和航速预报值与厂商提供的数值吻合良好,船B和船C的航速预报结果均与实船试航值比较接近,最大偏差小于0.5 kn.结果验证了计算模型的可信性和适用性,进一步表明该方法可较好地指导喷水推进器厂商根据船舶所有人的需求便捷地选出合适型号的喷水推进器.

Prediction and verification of waterejt boat speed based on thrust numerical calculation

In order to predict the speed of a waterjet propulsion ship accurately and quickly, a numerical model for calculating the thrust of the waterjet propulsion is established based on CFD method. A block hexahedral structured grid is used to discretize the computational domain, and the Reynolds-averaged Navier-Stokes equation and SST turbulence model are solved by the steady-state multi-reference system method to numerically simulate the flow field in the waterjet propulsion. The equal speed thrust curve of the water jet propeller is obtained by using the direct-thrust-integration method, and the intersection point is calculated by superposing it with the ship resistance curve to predict the speed. The thrust calculation value and speed prediction value of the water jet propeller configured by ship A are in good agreement with those provided by the manufacturer. The speed prediction results of ship B and ship C are close to the actual ship trial values, with the maximum deviation less than 0.5 knots. The possible causes of forecast errors are analyzed. Therefore, the credibility of the numerical model is verified, which can guide the waterjet manufacturers to conveniently select the appropriate type of waterjet according to the needs of ship owners, and can also provide a basis for the ship to formulate a reasonable working system.