Accession Number:
ADA238638
Title:
Control of Flow Over a Backward Facing Step
Descriptive Note:
Master's Thesis
Corporate Author:
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
Personal Author(s):
Report Date:
1990-09-01
Pagination or Media Count:
93.0
Abstract:
The poor aerodynamic design of the superstructures of todays Navy ships create a highly turbulent airwake that can make shipboard helicopter operations quite hazardous. This study is part of a longer-term project to tailor airflow over a ships helicopter deck in order to improve the poor quality of the airflow. This airflow is thought to be largely responsible for several costly blade strike mishaps involving H-46 helicopters during start-up and shut down. Numerous computer simulations were conducted using the Phoenics Computational Fluid Dynamics code to simulate airflow over a backward-facing- step. The latter represents a simple 2-d model of flow behind a typical hangar flight deck combination. In each run a deflector of different size, orientation or porosity was placed in a specific location in an attempt to reduce the size of the recirculation zone, the velocities and the turbulence levels. Of the studies involved, a vertical deflector offset downstream with its lower edge at the top of the step produced the best overall results.
Descriptors:
Subject Categories:
- Aerodynamics
- Fluid Mechanics