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.

Subject Categories:

  • Aerodynamics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE