Đang chuẩn bị liên kết để tải về tài liệu:
MODERN HELICOPTER AERODYNAMICS phần 1

Khí động học máy bay trực thăng hiện đại là một thách thức bởi vì các trường dòng chảy được tạo ra bởi máy bay trực thăng là cực kỳ phức tạp và khó khăn để đo lường, mô hình, và dự đoán, hơn nữa, các thí nghiệm tốn kém và khó khăn để tiến hành. Trong bài viết này, chúng tôi thảo luận về các nguyên tắc cơ bản của khí động học máy bay trực thăng hiện đại. | o MODERN HELICOPTER AERODYNAMICS A. T. Conlisk Department of Mechanical Engineering The Ohio State University Columbus Ohio 43210-1107 KEY WORDS rotor aerodynamics vortex wakes tip-vortex computational fluid dynamics experiments dynamic stall blade-vortex interaction Abstract Modern helicopter aerodynamics is challenging because the flow field generated by a helicopter is extremely complicated and difficult to measure model and predict moreover experiments are expensive and difficult to conduct. In this article we discuss the basic principles of modern helicopter aerodynamics. Many sophisticated experimental and computational techniques have been employed in an effort to predict performance parameters. Of particular interest is the structure of the rotor wake which is highly three-dimensional and unsteady and the rotor-blade pressure distribution which is significantly affected by the strength and position of the wake. We describe the various modern methods of computation and experiment which span the range from vortex techniques to full three-dimensional Navier-Stokes computations and from classical probe methods to laser velocimetry techniques. Typical results for the structure of the wake and the blade pressure distribution in both hover and forward flight are presented. Despite the complexity of the helicopter flow significant progress has been made within the last ten years and the future will likely bring marked advances. 1. INTRODUCTION For over 40 years the helicopter has played an important role in both military and civilian air transportation. In this article we discuss the basic principles of modern helicopter aerodynamics. In the past the term helicopter aerodynamics has been used synonymously with rotor-blade aerodynamics for the most part in this article we will consider this to be the case. However as will 515 0066-4189 97 0115-0515 08.00 516 CONLISK be noted later the term helicopter aerodynamics is now expanding to include interactions between many