Flutter of a Fan Blade in Supersonic Axial Flow

1989 ◽  
Vol 111 (4) ◽  
pp. 462-467 ◽  
Author(s):  
R. E. Kielb ◽  
J. K. Ramsey
Keyword(s):  
Mode Coupling ◽  
Axial Flow ◽  
Axial Flow Fan ◽  
Compressor Blades ◽  
Torsional Mode ◽  
Aerodynamic Loads ◽  
Aeroelastic Model ◽  
Parametric Studies ◽  
Fan Blade ◽  
Stagger Angle

An application of a simple aeroelastic model to an advanced supersonic axial flow fan is presented. Lane’s cascade theory is used to determine the unsteady aerodynamic loads. Parametric studies are performed to determine the effects of mode coupling, Mach number, damping, pitching axis location, solidity, stagger angle, and mistuning. The results show that supersonic axial flow fan and compressor blades are susceptible to a strong torsional mode flutter having critical reduced velocities that can be less than one.

Optimization of Stacking Line and Blade Profile for Design of Axial Flow Fan Blade

2008 ◽  
Author(s):  
Abdus Samad ◽  
Ki-Sang Lee ◽  
Kwang-Yong Kim
Keyword(s):  
Objective Function ◽  
Surrogate Model ◽  
Stokes Equations ◽  
Axial Flow ◽  
Weighted Average ◽  
Optimization Procedure ◽  
Total Efficiency ◽  
Blade Profile ◽  
Axial Flow Fan ◽  
Fan Blade

This work presents a numerical optimization procedure for a low-speed axial flow fan blade with weighted average surrogate model. Reynolds-averaged Navier-Stokes equations with SST turbulence model are discretized by finite volume approximations and solved on hexahedral grids for flow analyses. The blade profile as well as stacking line is modified to enhance blade total efficiency, i.e., the objective function. Six design variables related to blade lean and blade profile are selected, and a design of experiments technique produces design points where flow analyses are performed to obtain values of the objective function. PBA model is employed as a surrogate model for optimization. A search algorithm is used to find the optimal design in the design space from the constructed surrogate model for the objective function. As a main result, the efficiency is increased effectively by the present optimization procedure.

Discrete Frequency Noise Generation From an Axial Flow Fan Blade Row

1970 ◽  
Vol 92 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Ramani Mani
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Acoustic Energy ◽  
Frequency Noise ◽  
Noise Generation ◽  
Two Dimensional ◽  
Axial Flow Fan ◽  
Fan Noise ◽  
Blade Row ◽  
Fan Blade

An analysis is presented which treats the noise generation from an axial flow fan row by given forces including the effects of a moving medium. The linearization of Euler’s equations to yield tractable problems for fan noise is discussed. The three-dimensional problem is decomposed into several two-dimensional problems. Finally, full details are given of a two-dimensional analysis to predict the amounts of acoustic energy, at the blade passing frequency and its harmonics, radiated up and downstream of a blade row due to its interaction with a neighboring row.

Application of casing treatment to an industrial axial-flow fan

1998 ◽  
Vol 212 (4) ◽  
pp. 225-233 ◽  
Author(s):  
S D Hill ◽  
R L Elder ◽  
A B McKenzie
Keyword(s):  
Axial Flow ◽  
Rotating Stall ◽  
Strain Gauges ◽  
Axial Flow Fan ◽  
Fan Noise ◽  
Flow Measurements ◽  
Casing Treatment ◽  
Blade Tip ◽  
Fan Blade ◽  
Insight Into

This paper deals with an experimental investigation into the influence of a vaned recess casing treatment on the performance of an industrial-type axial-flow fan with a hub-tip ratio of 0.4. The treatment has been tested in a variety of configurations relative to the fan, with an emphasis on the amount of fan blade tip exposure to the treatment. Two sets of blading, one of which is of the fully reversible type, have been investigated. Detailed flow measurements have been carried out with a slanted hot wire probe to provide an insight into the operation of the device and into the nature of the rotating stall in the solid casing configuration. Strain gauges have been employed to enable blade stresses to be recorded and an in-duct microphone to enable comparative tests on fan noise has also been used.

Transonic Fan Blade Redesign Approach to Attenuate Nonsynchronous Vibration

2020 ◽  
Author(s):  
Yaozhi Lu ◽  
Bharat Lad ◽  
Mehdi Vahdati
Keyword(s):  
High Cycle Fatigue ◽  
Wave Pattern ◽  
Travelling Wave ◽  
Peak Efficiency ◽  
Aerodynamic Loads ◽  
Manufacturing Tolerance ◽  
Unsteady Effect ◽  
Fan Blade ◽  
Transonic Fan ◽  
Stagger Angle

Abstract Due to manufacturing tolerance and deterioration during operation, different blades in a fan assembly exhibit geometric variability. This leads to asymmetry which will be amplified in the running geometry by centrifugal and aerodynamic loads. This study investigates a phenomenon known as Alternate Passage Divergence (APD), where the blade untwist creates an alternating pattern in passage geometry and stagger angle around the circumference. After the formation of alternating tip stagger pattern, APD’s unsteady effect, APD-induced Non-Synchronous Vibration (APD-NSV), can cause the blades from one group to switch to the other creating a travelling wave pattern around the circumference. Thus, it can potentially lead to high cycle fatigue issues. More importantly, this phenomenon occurs close to, or at, peak efficiency conditions and can significantly reduce overall efficiency. Therefore, it is vital to attenuate the NSV behaviour. In this study, an redesign approach is investigated.

Characterization of Glass/Jute Hybrid Fibre Reinforced Epoxy Composite for Axial Flow Fan Blade

2019 ◽  
pp. 32-43
Author(s):  
Venkata sushma chinta ◽  
P. Ravinder Reddy ◽  
Koorapati Eshwara Prasad ◽  
Krishna Sai Vadapally ◽  
Sathola Anand ◽  
...  
Keyword(s):  
Epoxy Composite ◽  
Axial Flow ◽  
Axial Flow Fan ◽  
Hybrid Fibre ◽  
Fan Blade

Influence of Rotating Instability on Stall Inception Patterns in a Variable-Pitch Axial-Flow Fan

2006 ◽  
Author(s):  
Takahiro Nishioka ◽  
Shuuji Kuroda ◽  
Tsukasa Nagano ◽  
Hiroshi Hayami
Keyword(s):  
Rotor Blade ◽  
Axial Flow ◽  
Pressure Rise ◽  
Leading Edge ◽  
Rotating Stall ◽  
Axial Flow Fan ◽  
Tip Leakage Vortex ◽  
Stall Inception ◽  
Tip Leakage ◽  
Stagger Angle

An experimental study was conducted to investigate the inception patterns of rotating stall at different rotor blade stagger-angle settings with the aim of extending the stable operating range for a variable-pitch axial-flow fan. Pressure and velocity fluctuations were measured for a low-speed axial-flow fan with a relatively large tip clearance. Two stagger-angle settings were tested, the design setting, and a high setting which was 10 degrees greater than the design setting. Rotating instability (RI) was first observed near the peak pressure-rise point at both settings. It propagated in the rotation direction at about 40 to 50% of the rotor rotation speed, and its wavelength was about one rotor-blade pitch. However, the stall-inception patterns differed between the two settings. At the design stagger-angle setting, leading edge separation occurred near the stall-inception point, and this separation induced a strong tip leakage vortex that moved upstream of the rotor. This leakage vortex simultaneously induced a spike and a RI. The conditions for stall inception were consistent with the simple model of the spike-type proposed by Camp and Day. At the high stagger-angle setting, leading edge separation did not occur, and the tip leakage vortex did not move upstream of the rotor. Therefore, a spike did not appear although RI developed at the maximum pressure-rise point. This RI induced a large end-wall blockage that extended into the entire blade passage downstream of the rotor. This large blockage rapidly increased the rotor blade loading and directly induced a long length-scale stall cell before a spike or modal disturbance appeared. The conditions for stall inception were not consistent with the simple models of the spike or modal-type. These findings indicate that the movement of the tip leakage vortex associated with the rotor blade loading affects the development of a spike and RI and that the inception pattern of a rotating stall depends on the stagger-angle setting of the rotor blades.

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