Visualization and Analysis of V/STOL Twin Jet
Flow
Yasser M El-Okda
Engineering
Science and Mechanics Department
The Vertical Short Take-off and
Landing (VSTOL) aircraft is one of the promising aircraft configurations. They are
expected to play an important part in Military missions as well as in transportation
industry in the future. As the name implies, this Aircraft is designed to
take-off, hover, and land vertically like a helicopter. However, it has the
advantage over the helicopter that it can fly with the speed, range, and
efficiency of a fixed-wing airplane. There are a few configurations of the
lift power source. Some of the V/STOL models have twin jet engine in a
tandem arrangement with respect to the flow. The Jets are mounted so that they can rotate 90 degrees between vertical
and horizontal positions. The thrust of the vertical jets provides for vertical
take-off and vertical landing. Rotating the jets to assume the horizontal
position, they provide the V/STOL aircraft with a sufficient accelerating thrust
in order to
achieve high speed cruse. Other models adapt the same twin for only the vertical
STOL operation. An example of that is the Boeing version of the Joint
Strike Fighter (JSF) aircraft. On the other side The Lockheed Martin JSF
version exploits two successive vertical trust jets to achieve the
vertical STOL operation in which the rear jet is rotated to assume the
horizontal position to accelerate the aircraft.
The flow of the jets , with tandem arrangement with respect to the flow, when positioned vertically is
investigated. A model
of a plate with two jets impinging against the floor of the water tunnel in the
ESM Dept. Fluid Mechanics Laboratory. The flow of the jets and the their
interaction with the ground (the tunnel floor) is investigated. The jet flow was
investigated with and without free stream velocity.
This investigation
aims to prove that there is natural unsteadiness of the up wash flow
arising from the impingement of the tandem jet arrangement on the
ground.
Particle Image Velocimetry Technique is one of the greatest facilities in
the ESM fluid Mechanics Laboratory. The technique is useful in both flow
visualization and velocity measurement. The date is to be collected as flow
images for both the visualization and the analysis. Then, Processing the
images will be done by the a retail software package to extract the
velocity field. Post processing will be done by C++ code for calculation
of different flow field properties. With TechPlot retail software,
animations and images extraction together with different plots will be
done.
