On the unsteadiness of ship airwakes subject to atmospheric boundary-layer inflow from a helicopter operation perspective

Regis Thedin, Scott M. Murman, Joseph Horn, Sven Schmitz

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


In the present work, unsteady effects present in a ship airwake are further analyzed. The effort is performed in the context of simulation of helicopter launch and recovery operations under a realistic atmospheric inflow. A ship airwake is formed as a combination of the natural wind speed and ship motion, and the incoming flow is turbulent due to the presence of an atmospheric boundary layer (ABL). On a helicopter-ship dynamic interface simulation, accounting for the effects of an ABL can be important. Atmospheric boundary layers are different than typical engineering boundary layers, such as one over a flat plate. While in a time-averaged sense such boundary layers are comparable, real ABLs contain important unsteady features that set them apart. This work separates and quantifies effects inherently due to the unsteady atmosphere, and effects due to a sheared profile without atmospheric turbulence. Two cases are compared: (1) a realistic time-resolved ABL, and (2) a steady sheared velocity profile. Using a frequency-domain analysis of the control input sticks, it is observed that the energy increase in an unsteady ABL is considerably higher than the increase found under a steady sheared ABL, suggesting increased pilot workload at the relevant frequencies.

Original languageEnglish (US)
Title of host publicationAIAA Aviation 2019 Forum
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
Number of pages17
ISBN (Print)9781624105890
StatePublished - 2019
EventAIAA Aviation 2019 Forum - Dallas, United States
Duration: Jun 17 2019Jun 21 2019

Publication series

NameAIAA Aviation 2019 Forum


ConferenceAIAA Aviation 2019 Forum
Country/TerritoryUnited States

All Science Journal Classification (ASJC) codes

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Aerospace Engineering


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