Numerical investigation on the self-induced unsteadiness in tip leakage flow of a micro-axial fan rotor

2015 ◽  
Vol 24 (4) ◽  
pp. 334-343 ◽  
Author(s):  
Jinxin Chen ◽  
Huanxin Lai
Keyword(s):  
Numerical Investigation ◽  
The Self ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Axial Fan ◽  
Tip Leakage

Numerical Investigation on the Self-Induced Unsteadiness in Tip Leakage Flow for a Transonic Fan Rotor

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Juan Du ◽  
Feng Lin ◽  
Hongwu Zhang ◽  
Jingyi Chen
Keyword(s):  
Numerical Investigation ◽  
Driving Forces ◽  
Main Flow ◽  
Tip Clearance ◽  
The Self ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Blade Loading ◽  
Tip Leakage ◽  
Transonic Fan

A numerical investigation on the self-induced unsteadiness in tip leakage flow is presented for a transonic fan rotor. NASA Rotor 67 is chosen as the computational model. It is found that under certain conditions the self-induced unsteadiness can be originated from the interaction of two important driving “forces:” the incoming main flow and the tip leakage flow. Among all the simulated cases, the self-induced unsteadiness exists when the size of the tip clearance is equal to or larger than the design tip clearance. The originating mechanism of the unsteadiness is clarified through time-dependent internal flow patterns in the rotor tip region. It is demonstrated that when strong enough, the tip leakage flow impinges the pressure side of neighboring blade and alters the blade loading significantly. The blade loading in turn changes the strength of the tip leakage flow and results in a flow oscillation with a typical signature frequency. This periodic process is further illustrated by the time-space relation between the driving forces. A correlation based on the momentum ratio of tip leakage flow over the incoming main flow at the tip region is used as an indicator for the onset of the self-induced unsteadiness in tip leakage flow. It is discussed that the interaction between shock wave and tip leakage vortex does not initiate the self-induced unsteadiness, but might be the cause of other types of unsteadiness, such as broad-banded turbulence unsteadiness.

Numerical Investigation on the Originating Mechanism of Unsteadiness in Tip Leakage Flow for a Transonic Fan Rotor

2008 ◽  
Author(s):  
Juan Du ◽  
Feng Lin ◽  
Hongwu Zhang ◽  
Jingyi Chen
Keyword(s):  
Computational Model ◽  
Numerical Investigation ◽  
Main Flow ◽  
Tip Clearance ◽  
The Self ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Leakage Flows ◽  
Tip Leakage Flows

Despite the fact that the importance of steady tip leakage flows in rotor efficiency and stability has been long recognized and extensively studied, the unsteadiness of tip leakage flows became an interesting research topic only about 10 years ago. Many issues, such as its onset conditions, its role in compressor instability, etc. need to be further explored. In this paper, we present a numerical investigation on the influences of two important driving “forces”, the incoming main flow and the tip leakage flow, to clarify the originating mechanism of self-induced unsteadiness in transonic compressors. NASA Rotor 67 is chosen as the computational model. It is found that among all the simulated cases, the self-induced unsteadiness exists when the size of the tip clearance equals or larger than design tip clearance of the computational model. The time-dependent flow pattern in the rotor tip region is provided to illustrate that the main unsteady regions are on the blade’s pressure side that happens to be under the alternate influence of tip leakage flow and the incoming main flow. It is found the self-induced unsteady mechanism in the transonic rotor is the same as that in previously studied low-speed rotor. The interaction between shock wave and tip leakage vortex does not initiate the self-induced unsteadiness, but might be the cause of other unsteadiness, such as turbulent unsteadiness. A correlation based on the momentum ratio of tip leakage flow over the main incoming flow at the tip region is used as an indicator for the onset of the self-induced unsteadiness in tip leakage flow.

Analysis of tip-leakage flow in an axial fan at varying tip-gap sizes and operating conditions

2019 ◽  
Vol 183 ◽  
pp. 107-129 ◽  
Author(s):  
Seyed Mohsen Alavi Moghadam ◽  
Matthias Meinke ◽  
Wolfgang Schröder
Keyword(s):  
Operating Conditions ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Axial Fan ◽  
Tip Leakage

Tip leakage flow and aeroacoustics analysis of a low-speed axial fan

2020 ◽  
Vol 98 ◽  
pp. 105700 ◽  
Author(s):  
Bo Luo ◽  
Wuli Chu ◽  
Haoguang Zhang
Keyword(s):  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Axial Fan ◽  
Low Speed ◽  
Tip Leakage

Numerical Study on the Response of Tip Leakage Flow Unsteadiness to Micro Tip Injection in a Low-Speed Isolated Compressor Rotor

2007 ◽  
Author(s):  
Shaojuan Geng ◽  
Hongwu Zhang ◽  
Jingyi Chen ◽  
Weiguang Huang
Keyword(s):  
Numerical Study ◽  
The Self ◽  
Axial Position ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Low Speed ◽  
Tip Leakage ◽  
Flow Unsteadiness ◽  
Compressor Rotor ◽  
Tip Injection

A numerical study on the unsteady tip leakage flow with discrete micro tip injection from casing shroud in a low-speed isolated axial compressor rotor is presented. The main target is to clarify the flow mechanism of how the stall control measures act on the tip leakage flow typified by its self-induced unsteady flow characteristics. At operating condition near stall point, a series of calculations have been carried out for different axial position of injector and different injected mass flow rate. The computation results of flow field near rotor tip region show that under the influence of injected flow, the transient pressure distribution fluctuates along blade chord on both pressure and suction sides with respect to the relative position of injector and rotor. The pressure difference across the pressure and suction sides of compressor blade changes correspondingly, thus introduces a forced flow unsteadiness interacting with the unsteady tip leakage flow. When the injection is relatively strong and able to meet the tip leakage flow at its origination, the self-induced unsteadiness of tip leakage flow can be suppressed completely. In most cases, both frequency components of the self-induced unsteadiness and forced-induced unsteadiness are co-existing. The corresponding transient flow contours show that a local high pressure spot appears near blade pressure side, which moves downstream and shifts the tip leakage flow trajectory with less or without touching the neighboring pressure surface of the blade. Based on this understanding of discrete tip injection as force-induced flow unsteadiness, the numerical results are also analyzed to optimize the effect of injection in changing the route of tip leakage flow trajectories and therefore the chance of stability improvement of the compressor rotor.

The Self-induced unsteadiness of tip leakage flow in an axial low-speed compressor with single circumferential casing groove

2013 ◽  
Vol 22 (6) ◽  
pp. 565-572 ◽  
Author(s):  
Juan Du ◽  
Jichao Li ◽  
Kai Wang ◽  
Feng Lin ◽  
Chaoqun Nie
Keyword(s):  
The Self ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Low Speed ◽  
Tip Leakage

Experimental and numerical investigation of the unsteady tip leakage flow in axial compressor cascade

2013 ◽  
Vol 22 (2) ◽  
pp. 103-110 ◽  
Author(s):  
Chengqing Li ◽  
Tingfeng Ke ◽  
Jingxuan Zhang ◽  
Hongwu Zhang ◽  
Weiguang Huang
Keyword(s):  
Numerical Investigation ◽  
Axial Compressor ◽  
Leakage Flow ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Tip Leakage
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