Fan Noise Source Diagnostic Test- LDV Measured Flow Field Results

Abstract Applying a two-dimensional (2D) divergence-free (DF) interpolation to a one-person deployable unmanned underwater vehicle’s (UUV) noisy moving-vessel acoustic Doppler current profiler (MV-ADCP) measurements improves the results and increases the utility of the UUV in tidal environments. For a 3.5-h MV-ACDP simulation that spatially and temporally varies with the M2 tide, the 2D DF-estimated velocity magnitude and orientation improves by approximately 85%. Next the 2D DF method was applied to velocity data obtained from two UUVs that repeatedly performed seven 1-h survey tracks in Bear Cut Inlet, Miami, Florida. The DF method provides a more realistic and consistent representation of the ADCP measured flow field, improving magnitude and orientation estimates by approximately 25%. The improvement increases for lower flow velocities, when the ADCP measurements have low environmental signal-to-noise ratio. However, near slack tide when flow reversal occurs, the DF estimates are invalid because the flows are not steady state within the survey circuit.

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Two-step computational aeroacoustics approach for underhood cooling fan application

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-2467 ◽

2021 ◽

Vol 263 (3) ◽

pp. 3615-3624

Author(s):

Parag Chaudhari ◽

Jose Magalhaes ◽

Aparna Salunkhe

Keyword(s):

Flow Field ◽

Sound Pressure ◽

Acoustic Analysis ◽

Air Flow ◽

Computational Aeroacoustics ◽

Noise Sources ◽

Fan Noise ◽

Cooling Fan ◽

Sound Pressure Levels ◽

One Step

Aeroacoustic noise is one of the important characteristics of the fan design. Computational Aeroacoustics (CAA) can provide better design options without relying on physical prototypes and reduce the development time and cost. There are two ways of performing CAA analysis; one-step and two-step approach. In one-step CAA, air flow and acoustic analysis are carried out in a single software. In two-step approach, air flow and acoustic analysis are carried out in separate software. Two-step CAA approach can expedite the calculation process and can be implemented in larger and complex domain problems. For the work presented in this paper, a mockup of an underhood cooling fan was designed. The sound pressure levels were measured for different installation configurations. The sound pressure level for one of the configurations was calculated with two-step approach and compared with test data. The compressible fluid flow field was first computed in a commercially available computational fluid dynamics software. This flow field was imported in a separate software where fan noise sources were computed and further used to predict the sound pressure levels at various microphone locations. The results show an excellent correlation between test and simulation for both tonal and broadband components of the fan noise.

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Fan noise visualization and noise source identification by using nearfield acoustical holography.

The Journal of the Acoustical Society of America ◽

10.1121/1.3508467 ◽

2010 ◽

Vol 128 (4) ◽

pp. 2381-2381

Author(s):

Yaying Niu ◽

Yong‐Joe Kim

Keyword(s):

Source Identification ◽

Noise Source ◽

Fan Noise ◽

Noise Source Identification ◽

Acoustical Holography ◽

Nearfield Acoustical Holography

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Measurement of 3D Flow Structure of Viscoelastic Fluid Using Digital Holographic Microscope

Volume 2: Fora ◽

10.1115/ajkfluids2015-10310 ◽

2015 ◽

Author(s):

Xiao-Bin Li ◽

Masamichi Oishi ◽

Tsukasa Matsuo ◽

Marie Oshima ◽

Feng-Chen Li ◽

...

Keyword(s):

Flow Field ◽

Real Time ◽

Viscoelastic Fluid ◽

Three Dimensional ◽

Complex Flow ◽

Micro Particle Image Velocimetry ◽

Dimensional Measurement ◽

Tracer Particles ◽

Three Dimensional Measurement ◽

Measured Flow

This paper aims to develop a three-dimensional measurement approach to investigate the flow structures of viscoelastic fluid in the curved microchannel by using digital holographic microscope (DHM). With the advantage of DHM, the real-time three-dimensional measurement for the complex flow field can be accomplished. The measurment system uses off-axis holographic / interferometric optical setup for the target, and 3D3C particle tracking velocimetry (PTV) can be achieved based on the analysis of phase information of holograms. To diagnose the chaotic flow inside the microchannel, the 3D temporal positions of tracer particles in the volume of 282μm × 282μm × 60μm have been detected and real-time velocity vectors were calculated based on the PTV algorithm. The measured flow field was then compared with the results obtained by using confocal micro particle image velocimetry (PIV). This technique is proven to be successful for the measurements of microfluidic flow, especially for the truly real-time 3D motions.

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Three-Dimensional Flow Field in Rocket Pump Inducers—Part 1: Measured Flow Field Inside the Rotating Blade Passage and at the Exit

Journal of Fluids Engineering ◽

10.1115/1.3447071 ◽

1973 ◽

Vol 95 (4) ◽

pp. 567-578 ◽

Cited By ~ 2

Author(s):

B. Lakshminarayana

Keyword(s):

Flow Field ◽

Three Dimensional ◽

Layer Growth ◽

Surface Boundary ◽

Suction Surface ◽

Flow Losses ◽

Rotating Blade ◽

Order Of Magnitude ◽

Measured Flow ◽

Boundary Layer Growth

The measurement of the flow field within the rotating passages as well as three-dimensional characteristics of the exit flow of an inducer model is reported in this paper. The flow within the inducer is probed by means of rotating pitot probe and pressure transfer device and at the exit by means of three hot wires located in three coordinate directions. In a high solidity inducer (4 bladed), considerable boundary layer growth is observed from hub to mid radius, while the flow from mid radius to tip is found to be highly complex, due to interaction of pressure and suction surface boundary layers and the resulting radial inward flow. The flow losses and wall shear stress derived from these measurements are found to be considerably higher than the corresponding stationary channel. The radial velocities are found to be of the same order of magnitude as axial velocities. Considerable improvement in the flow field is observed when the number of blades is decreased from four to three.

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