TY - GEN
T1 - On the unsteadiness of ship airwakes subject to atmospheric boundary-layer inflow from a helicopter operation perspective
AU - Thedin, Regis
AU - Murman, Scott M.
AU - Horn, Joseph
AU - Schmitz, Sven
N1 - Funding Information:
This research is partly supported by the Government under Agreement No. W911W6-17-2-0003. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Aviation Development Directorate or the U.S. Government. Many thanks are directed to Dr. William Chan, Dr. Marie Deninson, and Dr. Anirban Garai from NASA Ames for their help generating the overset grids. Discussions with Dr. Jim Coder are also appreciated. Simulations were made possible on the Pleiades supercomputer at NASA Ames Research Center, and the HPC infrastructure available in the Department of Aerospace Engineering at Penn State.
Publisher Copyright:
© 2019 American Institute of Aeronautics and Astronautics. All rights reserved.
PY - 2019
Y1 - 2019
N2 - 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.
AB - 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.
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U2 - 10.2514/6.2019-3032
DO - 10.2514/6.2019-3032
M3 - Conference contribution
AN - SCOPUS:85099069350
SN - 9781624105890
T3 - AIAA Aviation 2019 Forum
SP - 1
EP - 17
BT - AIAA Aviation 2019 Forum
PB - American Institute of Aeronautics and Astronautics Inc, AIAA
T2 - AIAA Aviation 2019 Forum
Y2 - 17 June 2019 through 21 June 2019
ER -