شبكة التخطيط العمراني بسم الله الرحمن الرحيم
للكاتبين :
A.M. El-Zahaby, A. Khalil, E.A. El-Shenawy and M.I. Amr
Department of Mechanical Power Engineering, Tanta University, Egypt
ABSTRACT
The internal flow structure in a centrifugal pump impeller is investigated using Particle Image
Velocimetry (PIV). The measurements are performed in a Perspex model of an industrial centrifugal
impeller employing fluorescent seeding particles to give full access to near-wall flows. A large number
of velocity vector maps are acquired by conditional sampling in a vertical constant-width plane
between hub and shroud of the impeller. The field of view in effect is the full impeller passages.
Instantaneous and ensemble-averaged velocity vector maps are transformed to the moving frame and
analyzed for the purpose of identifying steady and unsteady flow phenomena at different flow rates
with the main focus on off-design conditions as well as the cavitation conditions. High levels of
turbulence are confined to near-wall regions along the inlet and outlet surfaces of the impeller.
Experimental results from PIV system, concerning pump characteristics and performance breakdown,
were compared at different flow conditions. Appearing types of cavitation and the spatial distribution
of vapor structure within the runner are also analyzed. Analysis of the obtained data concerning
cavitating flow, turbulent kinetic energy or turbulence intensity may be taken as a parameter for
detecting cavitation. The significance of this study appears in understanding the turbulence
characteristics inside the centrifugal pump impeller. Moreover, it can help in developing flow
prediction codes.