scholarly journals Effect of Blade Curvature on Fan Integration in Engine Cooling Module

Acoustics ◽  
2020 ◽  
Vol 2 (4) ◽  
pp. 776-790
Author(s):  
Manuel Henner ◽  
Bruno Demory ◽  
Mohamed Alaoui ◽  
Maxime Laurent ◽  
Benjamin Behey
Keyword(s):  
Heat Exchangers ◽  
Sound Pressure ◽  
Sound Propagation ◽  
Density Fluctuations ◽  
Pressure Level ◽  
Good Efficiency ◽  
Vortical Structures ◽  
Engine Cooling ◽  
Blade Tip ◽  
Cooling Module

Two blade curvatures representative of those found in automotive fans are compared. Measured performances are analyzed for forward and backward curved blades, either with or without heat-exchangers placed in front of them. The backward fan demonstrated good efficiency but poor acoustics, whereas it is the contrary for the forward fan. Investigations are completed by a numerical analysis of the flow in the cooling module. Different integration effects are highlighted depending on the blade curvature, showing variation in pressure, torque and efficiency. Analyses of blade loadings show that the flow is more homogeneous with a forward curved fan and it produces less unsteadiness at the blade tip. Post-processing of detached eddy simulations (DES) shows density fluctuations on the blade wall and confirms the correlation between the large vortical structures and the acoustic sources for both fans. In addition, with the forward fan, the sound propagation is less directed towards the axis of rotation and it yields up to −3.6 dB of sound pressure level (SPL) measured in front of the cooling module. As a conclusion, any choice for a fan must result from a compromise between aerodynamics and aeroacoustics, and the final performances must be carefully checked on the module.

scholarly journals Leakage Noise and Related Flow Pattern in a Low-Speed Axial Fan with Rotating Shroud

2019 ◽  
Vol 4 (3) ◽  
pp. 17 ◽  
Author(s):  
Edward Canepa ◽  
Andrea Cattanei ◽  
Fabio Mazzocut Zecchin
Keyword(s):  
Flow Separation ◽  
Sound Pressure Level ◽  
Rotational Speed ◽  
Sound Pressure ◽  
Pressure Level ◽  
Leakage Flow ◽  
Axial Fan ◽  
Blade Loading ◽  
Flow Noise ◽  
Blade Tip

The effect of rotational speed and pressure rise on the leakage flow noise radiated by a low-speed axial fan, provided with rotating shroud, has been systematically investigated. The flow in the gap region has been studied by means of particle image velocimetry (PIV) measurements taken in the meridional plane. At low blade loading, the leakage flow is restrained close to the rotor ring and, at higher loading, it forms a wide recirculation zone. In the latter conditions, an unsteady flow separation likely takes place in the blade tip region which may be observed in the instantaneous flow field only. The leakage flow noise generally increases with the blade loading, but is non-monotonic, as the overall sound pressure level (OASPL) growth is interrupted by local minima; such a trend is qualitatively independent of the rotational speed. As the loading increases, the sound pressure level (SPL) spectrum shows important modifications, since the characteristic frequency of the subharmonic narrowband humps related to the leakage noise decreases; furthermore, height and width of the humps vary non-monotonically. Such a complicated behavior is likely related to the modifications in the leakage flow pattern and also to the appearance of the flow separation at the blade tip.

scholarly journals Experimental verification of design calculations of the internal combustion engine cooling system

2019 ◽  
Vol 179 (4) ◽  
pp. 132-135
Author(s):  
Barbara WORSZTYNOWICZ
Keyword(s):  
Heat Exchangers ◽  
Cooling System ◽  
Combustion Engine ◽  
Special Purpose Vehicle ◽  
Engine Cooling ◽  
Measurement Results ◽  
Calculation Results ◽  
Cooling Module ◽  
Design Calculations ◽  
Made In

The article presents a comparative analysis of calculation results and measurement results of cooling module built on the basis of design calculations. The computations were made in software dedicated to the calculations of heat exchangers. The measurements were performed on a cooling system mounted in a special purpose vehicle together with a combustion engine, which was loaded by an engine dynamometer. Based on the comparison between input data for calculations and results of measurements, differences were found, therefore changes were proposed to be made in the model.

Technical Note: Prediction of the Characteristics of Complicated Sound Fields in Long Enclosures by a Beam-Tracing Method

2002 ◽  
Vol 9 (2) ◽  
pp. 139-150 ◽  
Author(s):  
Xiangyang Zeng ◽  
Jincai Sun ◽  
Ke'an Chen
Keyword(s):  
Sound Pressure ◽  
Sound Propagation ◽  
Sound Field ◽  
Technical Note ◽  
Pressure Level ◽  
Reverberation Time ◽  
Complex Sound ◽  
Sound Fields ◽  
Sound Receiver ◽  
The Subject

The subject of this paper is the characterisation of the sound field in long enclosures. A beam-tracing computer model has been developed especially for the simulation of sound propagation throughout long enclosures. Surface diffusing reflection and air absorption are included in the model, which can predict the impulse response and acoustic indexes at arbitrary positions in the enclosure. This paper describes how the algorithm models the sound source, sound propagation and sound receiver. The algorithm was then tested in both common rooms and long enclosures by comparison of the measurement, theoretical calculation and prediction results. The characteristics of more complex sound fields in long enclosures, the prediction of reverberation time, early decay time and sound pressure level, etc, at individual points are discussed in terms of the algorithm. The results indicate that the primary characteristics of complicated sound fields in non-rectangular long enclosures are similar to those in rectangular ones.

The Effects of the Jet-Flow on Sound Propagation in Low-Speed Wind Tunnel

2012 ◽  
Vol 226-228 ◽  
pp. 368-373
Author(s):  
Yi Gang Wang ◽  
Jia Shun Yang ◽  
Yang Yang ◽  
Zhi Gang Yang
Keyword(s):  
Wind Tunnel ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Propagation ◽  
Prediction Method ◽  
Test Sample ◽  
Jet Flow ◽  
Pressure Level ◽  
High Frequency Signal ◽  
Low Speed Wind Tunnel

Based on the open-jet aero-acoustic wind tunnel, an experimental study was made to research the effects of the jet-flow on sound propagation. This study is focused on the changes of the direction of the sound propagation, the changes of the sound pressure level, the phenomenon of tone broadening and the availability of the existing prediction method for sound propagation in jet-flow. The results indicate that the influence of the jet-flow on the value of the noise source shift varies along the direction of the jet-flow and there is no regular influence on the sound pressure level. In addition, the flow around the test sample has affected the sound propagation, and the phenomenon of tone broadening exists when high frequency signal is used. The study also reveals the limitation of the application of the existing prediction method, because the model it used is too simple.

Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

2020 ◽  
Vol 63 (4) ◽  
pp. 931-947
Author(s):  
Teresa L. D. Hardy ◽  
Carol A. Boliek ◽  
Daniel Aalto ◽  
Justin Lewicke ◽  
Kristopher Wells ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Vocal Tract ◽  
Presentation Mode ◽  
Pressure Level ◽  
Presentation Modes ◽  
Audiovisual Stimuli ◽  
Vocal Tract Resonance ◽  
Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

Influence of the Acoustic Reflex on Vowel Recognition

1986 ◽  
Vol 29 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Michael Dorman ◽  
Ingrid Cedar ◽  
Maureen Hannley ◽  
Marjorie Leek ◽  
Julie Mapes Lindholm
Keyword(s):  
Auditory System ◽  
Sound Pressure ◽  
Dynamic Range ◽  
Recognition Accuracy ◽  
Pressure Level ◽  
Acoustic Reflex ◽  
The Poor ◽  
Stapedial Reflex ◽  
Vowel Recognition ◽  
High Sound

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

Sign in / Sign up

Export Citation Format

Share Document