Human CFD(Complement factor D) ELISA Kit

The objective of this work is to evaluate the surge characteristics of an axial compressor operating under surge conditions, by using a hybrid BDF/harmonic balance method. During a surge event, a large amount of backflow occurs in the compressor. Consequently, the airflow oscillates along the axial direction at a low frequency, which can considerably damage the compressor. In this paper, a numerical investigation is performed to examine the effects of the system volume and average mass flow on the surge characteristics of a transonic high speed single stage axial compressor (stage 35) designed and evaluated at the NASA Glenn Center. The results show that the oscillation frequency of the airflow in the compressor generally ranges from 14.32-26.04 Hz during surge conditions, and both the system volume and average mass flow considerably influence the surge characteristics. For a constant average mass flow, as the system volume decreases, the oscillation frequency of the airflow in the compressor increases slightly, while the oscillation amplitude of the exit static pressure decreases significantly, and the maximum static pressure at the outlet remains nearly constant. In the case of a constant system volume, with the decrease in the average mass flow, the oscillation frequency of the airflow in the compressor gradually decreases, and the oscillation amplitude of the exit pressure increases significantly. With a further decrease in the average mass flow, the oscillation frequency stabilizes at a certain point and does not change thenceforth. Furthermore, the surge frequency obtained using the numerical method shows a same tendency with the Helmholtz frequency, but there is a considerable difference between them. (C) 2020 Elsevier Masson SAS. All rights reserved.

Fan-wing thrusters are primarily used for aircraft propulsion, but their potential for underwater applications has also been demonstrated. Although many achievements have been made through experimentation, there still remains much work to be done in mechanism and hydrodynamic analyses, especially for the underwater fan-wing thruster (UFT). In this work, experiments are designed and carried out for a UFT. Both self-driving and towing experiments are conducted with a custom-made experiment device. In the self-driving experiments, vertical force and velocity are measured at different rotational speeds of the cross-flow fan. Then, for studying the hydrodynamic performance, specific towing experiments and computational fluid dynamics (CFD) simulations are carried out. Simulation results are in good agreement with the towing experiment results. On the basis of the CFD simulation results, specific unique characteristics are identified. Finally, a physical model is built and analyzed, and the mechanism and distinctive characteristics are explained by the physical model. (c) 2020 Elsevier Ltd. All rights reserved.