Unsteady Surface Pressure Characteristics on Aircraft Components and Far-Field Radiated Airframe Noise

1978 ◽  
Vol 15 (12) ◽  
pp. 809-815 ◽  
Author(s):  
Hanno H. Heller ◽  
Werner M. Dobrzynski
Keyword(s):  
Surface Pressure ◽  
Far Field ◽  
Airframe Noise ◽  
Unsteady Surface Pressure ◽  
Pressure Characteristics

Experimental and Unsteady Numerical Investigation of the Tip Clearance Noise of an Axial Fan

2013 ◽  
Author(s):  
Tao Zhu ◽  
Thomas H. Carolus
Keyword(s):  
Surface Pressure ◽  
Temporal Structure ◽  
Pressure Fluctuations ◽  
Tip Clearance ◽  
Tip Vortex ◽  
Far Field ◽  
Axial Fan ◽  
Clearance Ratio ◽  
Wall Pressure Fluctuations ◽  
Unsteady Surface Pressure

The aerodynamic and aeroacoustic performance of axial fans are strongly affected by the unavoidable tip clearance. Two identical fan impellers but with different tip clearance ratio were investigated. Unsteady wall pressure fluctuations in the tip region of the rotating blades and on the interior wall of the duct type shroud and the overall sound radiated were analysed by an unsteady numerical Scale-Adaptive Simulation (SAS) and unsteady surface pressure measurements in both, the stationary and rotating system. Based on SAS-predicted pressure fluctuations on the blade surfaces the acoustic analogy according to Ffowcs Williams and Hawkings (FWH) was employed to calculate the sound pressure in the far field. In general, experimentally and numerically determined unsteady flow were found to be a tendentially good agreement. The spatial and temporal structure of the tip vortex system and the resulting unsteady pressure distribution on the surfaces in the vicinity of the blade tips was revealed in good detail. The vortices’ strength and trajectories as well as the unsteadiness are controlled by the size of the tip clearance and the operating point: As tip clearance is increased blade/vortex interaction becomes more prevalent and with it the unsteady surface pressure and eventually the sound radiated into the far field. The broadband tip clearance noise was acceptably predicted from the simulation results, while the prediction at discrete frequency should still be improved in the further work.

Aeroacoustic analysis of slat tones

2021 ◽  
Vol 263 (1) ◽  
pp. 5650-5663
Author(s):  
Hasan Kamliya Jawahar ◽  
Syamir Alihan Showkat Ali ◽  
Mahdi Azarpeyvand
Keyword(s):  
Wavelet Transform ◽  
Surface Pressure ◽  
Wavelet Coefficient ◽  
Pressure Fluctuations ◽  
Low Frequency ◽  
Stream Velocity ◽  
High Lift ◽  
Unsteady Surface Pressure ◽  
Slat Noise ◽  
Generation Mechanisms

Experimental measurements were carried out to assess the aeroacoustic characteristics of a 30P30N high-lift device, with particular attention to slat tonal noise. Three different types of slat modifications, namely slat cove filler, serrated slat cusp, and slat finlets have been experimentally examined. The results are presented for an angle of attack of α = 18 at a free-stream velocity of U = 30 m/s, which corresponds to a chord-based Reynolds number of Re = 7 x 10. The unsteady surface pressure near the slat region and far-field noise were made simultaneously to gain a deeper understanding of the slat noise generation mechanisms. The nature of the low-frequency broadband hump and the slat tones were investigated using higher-order statistical approaches for the baseline 30P30N and modified slat configurations. Continuous wavelet transform of the unsteady surface pressure fluctuations along with secondary wavelet transform of the broadband hump and tones were carried out to analyze the intermittent events induced by the tone generating resonant mechanisms. Stochastic analysis of the wavelet coefficient modulus of the surface pressure fluctuations was also carried out to demonstrate the inherent differences of different tonal frequencies. An understanding into the nature of the noise generated from the slat will help design the new generation of quite high-lift devices.

Unsteady Pressure Measurement on Oscillating Blade in Transonic Flow Using Fast-Response Pressure-Sensitive Paint

2017 ◽  
Author(s):  
Toshinori Watanabe ◽  
Toshihiko Azuma ◽  
Seiji Uzawa ◽  
Takehiro Himeno ◽  
Chihiro Inoue
Keyword(s):  
Surface Pressure ◽  
Transonic Flow ◽  
Aerodynamic Force ◽  
Fast Response ◽  
Pressure Sensitive Paint ◽  
Unsteady Pressure ◽  
Pressure Distributions ◽  
Pressure Sensitive ◽  
Unsteady Surface Pressure ◽  
Response Pressure

A fast-response pressure-sensitive paint (PSP) technique was applied to the measurement of unsteady surface pressure of an oscillating cascade blade in a transonic flow. A linear cascade was used, and its central blade was oscillated in a translational manner. The unsteady pressure distributions of the oscillating blade and two stationary neighbors were measured using the fast-response PSP technique, and the unsteady aerodynamic force on the blade was obtained by integrating the data obtained on the pressures. The measurements made with the PSP technique were compared with those obtained by conventional methods for the purpose of validation. From the results, the PSP technique was revealed to be capable of measuring the unsteady surface pressure, which is used for flutter analysis in transonic conditions.

Surface pressure characteristics of a highly loaded turbine blade at design and off-design conditions; a CFD methodology

2017 ◽  
Vol 24 (3) ◽  
pp. 469-482
Author(s):  
S. Vakilipour ◽  
M. Habibnia ◽  
M. H. Sabour ◽  
R. Riazi ◽  
M. Mohammadi
Keyword(s):  
Turbine Blade ◽  
Surface Pressure ◽  
Highly Loaded ◽  
Pressure Characteristics

Full 3-D Unsteady Numerical Simulation of Control Stage in Partial Admission Turbine

2015 ◽  
Vol 741 ◽  
pp. 509-512
Author(s):  
Guo Ping Li ◽  
Ke Ke Gao ◽  
Ke Yang ◽  
Yong Hui Xie
Keyword(s):  
Numerical Simulation ◽  
Surface Pressure ◽  
Flow Parameters ◽  
Control Stage ◽  
Air Turbine ◽  
Unsteady Surface Pressure ◽  
Partial Admission ◽  
Unsteady Numerical Simulation ◽  
Pressure Changes ◽  
Mixing Losses

The unsteady flow parameters in control stage of partial admission are analyzed in details with full 3-D numerical simulation. The full annulus structure of air turbine in partial admission is modeled due to the unsymmetrical geometry. The partial admission is accomplished through the inlet blocked using segmental arc. The unsteady surface pressure changes of eight blades in the transition regions which demonstrate the power output ability are presented. That the entropy rise associated with the losses at different cross mainly caused by mixing losses and flow separation in partial admission is analyzed to estimate the efficiency distribution.

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