PRACTICAL BOUNDARY IN HELICOPTER VORTEX-RING STATE

摘要

A reasonable criterion of vortex-ring state boundary for helicopter is acquired based on model rotor tests. According to this criterion a non-dimensional vortex-ring state boundary is presented for general application. To validate the boundary, flight tests are carried out and some new conclusions are drawn. Combined theoretical and experimental research with the flight test results, the concept of two curves & three regions is brought out, which makes the chart of vortex-ring boundary more reasonable and practical.