Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Numerical loss analysis in a compressor cascade with leading edge tubercles

Zheng T., Qiang X.-Q., Teng J.-F., Teng J.-Z.

Journal of Theoretical and Applied Mechanics

2018

Vol. 56 nr 4

1083--1095

A numerical analysis of loss has been carried out to explore the loss mechanism of leading edge tubercles in a high speed compressor cascade. Taking the lead from flippers of the humpback whale, tubercles are passive structures of a blade for flow control. Evaluation of the overall performance in terms of entropy increase shows that the loss reduction is achieved both at high negative and high positive incidence angles, while a rise in the loss is obtained near the design point. And a smaller wave number as well as a smaller amplitude results in lower additional losses at the design point. Spanwise and streamwise distributions of pitchwise-averaged entropy increase combined with flow details have been presented to survey the loss development and, subsequently, to interpret the loss mechanism. The tubercle geometry results in the deflection flow and the consequent spanwise pressure gradient. This pressure gradient induces formation of counter-rotating streamwise vortices, transports away the low-momentum fluid near wall from crests towards troughs and leads to local high loss regions behind troughs as well as loss reduction behind the crests in comparison to the baseline. The interaction between these vortices and flow separation by momentum transfer leads to separation delay and the consequent loss reduction at the outlet.

Assessment of marine ecosystem health of Tianjin Offshore, China

Zheng T., You X. Y.

Oceanological and Hydrobiological Studies

2013

Vol. 42, No. 4

442--450

While the marine ecosystem health is damaged by economic activities, pollution and reclamation projects, the assessment of marine ecosystem health is strongly required to facilitate its maintenance, improvement and management. In this study, the health of the Tianjin marine ecosystem was quantitatively assessed using the ocean health index in which ten public goals are considered. The results indicated that the ocean health index for the Tianjin marine ecosystem is 66, which is higher than the global ocean health index of 60. This indicated that the overall health of the Tianjin marine ecosystem is barely good and the suitable environmental management and measures should be implemented carefully and effectively in the future.