求翻译：本文是对直升机噪声特性的总结分析以及预测技术发展综述。分析了旋翼气动噪声的分类及产生的机理，并且指出旋翼气动噪声分析中的热点及难点。同时对气动噪声的预测技术的发展进行了简要的总结，国外发展相对较成熟，已经形成了可以用于工程实际分析的大型软件；而国内发展起步较晚，目前很多都属于方法的研究阶段，有很多独特的观点和方法，对旋翼噪声分析具有实际意义。是什么意思？

This article is a summary of the characteristics of helicopter noise analysis and prediction of Technology and Development. The classification of the rotor aerodynamic noise generation mechanism, and noted that the rotor aerodynamic noise analysis of hotspots and difficult. A brief summary of the de

This article is to summarize the helicopter noise characteristics, as well as forecasting analysis technology development overview. Analysis of the pneumatic rotary-wing of the classification and the resulting noise of the machines, pneumatic rotary wing and noted that the noise analysis of hot spot

This article is a summary analysis of helicopter noise characteristics and prediction technology review. Analysis of the rotor classification and generation mechanism of aerodynamic noise, and pointed out that hot and difficult points of the rotor in analysis of aerodynamic noise. Prediction of aero