scholarly journals Acoustic analysis of selected sacred buildings in Szczecin

2021 ◽  
Vol 20 (4) ◽  
pp. 017-036
Author(s):  
Agata Stolarska ◽  
Jarosław Strzałkowski ◽  
Agata Kandybowicz
Keyword(s):  
Pressure Drop ◽  
Research Methodology ◽  
Basic Parameter ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Liturgical Music ◽  
Reverberation Time ◽  
Organ Music ◽  
Response Method ◽  
Better Than

The aim of this study was to assess acoustically selected sacred buildings located in Szczecin. The research part contains the research methodology and the results obtained. The research was carried out using two methods. The first one is the integrated impulse response method, where, using a bursting balloon, the time of sound pressure drop was measured at selected points of the object. In the interrupted noise method, the sound pressure drop was measured after the noise generated by the omnidirectional loudspeaker had ceased. Reverberation time was calculated for the results obtained, which is the main and basic parameter determining the interior acoustics. On the basis of the above-mentioned measurements, the reverberation indicators for the temples were also calculated. When analyzing the components of the reverberation indicator, it was noticed that poor acoustics in the sanctuary concerns speech, while interior acoustics is good for the reception of organ music. In the analyzed church, the reception of liturgical music is also better than the reception of speech, but the differences between these values are small.

Thermohydraulics of Laminar Flow Through Rectangular and Square Ducts With Transverse Ribs and Twisted Tapes

2006 ◽  
Vol 128 (10) ◽  
pp. 1070-1080 ◽  
Author(s):  
Debashis Pramanik ◽  
Sujoy K. Saha
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Laminar Flows ◽  
Short Length ◽  
Full Length ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Square Ducts ◽  
Better Than

The heat transfer and the pressure drop characteristics of laminar flow of viscous oil through rectangular and square ducts with internal transverse rib turbulators on two opposite surfaces of the ducts and fitted with twisted tapes have been studied experimentally. The tapes have been full length, short length, and regularly spaced types. The transverse ribs in combination with full-length twisted tapes have been found to perform better than either ribs or twisted tapes acting alone. The heat transfer and the pressure drop measurements have been taken in separate test sections. Heat transfer tests were carried out in electrically heated stainless steel ducts incorporating uniform wall heat flux boundary conditions. Pressure drop tests were carried out in acrylic ducts. The flow was periodically fully developed in the regularly spaced twisted-tape elements case and decaying swirl flow in the short-length twisted tapes case. The flow characteristics are governed by twist ratio, space ratio, and length of twisted tape, Reynolds number, Prandtl number, rod-to-tube diameter ratio, duct aspect ratio, rib height, and rib spacing. Correlations developed for friction factor and Nusselt number have predicted the experimental data satisfactorily. The performance of the geometry under investigation has been evaluated. It has been found that on the basis of both constant pumping power and constant heat duty, the regularly spaced twisted-tape elements in specific cases perform marginally better than their full-length counterparts. However, the short-length twisted-tape performance is worse than the full-length twisted tapes. Therefore, full-length twisted tapes and regularly spaced twisted-tape elements in combination with transverse ribs are recommended for laminar flows. However, the short-length twisted tapes are not recommended.

Evaluation Analysis of Prediction Methods for Two-Phase Flow Pressure Drop in Mini-Channels

2008 ◽  
Author(s):  
Licheng Sun ◽  
Kaichiro Mishima
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Turbulent Region ◽  
Frictional Pressure Drop ◽  
New Correlation ◽  
Mini Channels ◽  
Flow Pressure ◽  
Better Than

2092 data of two-phase flow pressure drop were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12mm; Relo from 10 to 37000, and Rego from 3 to 4×105. 11 correlations and models for calculating the two-phase frictional pressure drop were evaluated based upon these data. The results show that the accuracy of the Lockhart-Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correalion in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. A modified Chisholm correlation was proposed, which is better than all of the evaluated correlations in the turbulent region and its mean relative error is about 29%. For refrigerants only, the new correlation and Muller-Steinhagen and Heck correlation are very close to each other and give better agreement than the other evaluated correlations.

scholarly journals ACOUSTIC ANALYSIS AND MEASUREMENTS OF MEGA YACHTS DURING CONSTRUCTION

2019 ◽  
Author(s):  
M Insel ◽  
S Gokcay ◽  
Z Saydam ◽  
T Soyaslan ◽  
C Soyaslan
Keyword(s):  
Final Stage ◽  
Critical Parameter ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Prediction Tool ◽  
Transmission Losses ◽  
Sea Trial ◽  
Airborne Noise ◽  
Building Project

Noise is a critical parameter for super/mega yachts which can be verified only in the final stage of a mega yacht building project. Although there are more and more advanced methods to predict noise prior to the sea trials, verification has to be delayed until the noise survey is conducted during the sea trial. A new methodology is proposed based on measurements during construction to determine the transmission losses of both airborne and structure borne noise and propagation of the sound from the source to the receiver using these measurements. A 66 meter mega yacht case study is presented with measurements of airborne noise emitted through an omni-directional dodecahedron loudspeaker and measurements of structure borne noise generated by a tapping device. Both sound pressure levels and vibrations are measured to derive the transmission losses. A source-path-receiver method-based prediction tool, SNoPP, is employed to project the measurements into the final noise predictions. Comparisons between the measurements and the predictions are also presented.

scholarly journals CO2 Pipeline Design: A Review

2018 ◽  
Author(s):  
Suoton P. Peletiri ◽  
Nejat Rahmanian ◽  
Iqbal M. Mujtaba
Keyword(s):  
Pressure Drop ◽  
Flow Equation ◽  
Aspen Hysys ◽  
Resultant Velocity ◽  
Velocity Flow ◽  
Effect Of Impurities ◽  
Paris Climate Agreement ◽  
Second Category ◽  
Pipeline Design ◽  
Better Than

There is need to accurately design pipelines to transport the expected increase of CO2 captured from industrial processes after the signing of the Paris Climate Agreement in 2016. This paper reviews several aspects of CO2 pipeline design with emphasis on pressure drop and models for the calculation of pipeline diameter. Two categories of pipeline equations were identified. The first category is independent of pipeline length and has two different equations. This category is used to specify adequate pipeline diameter for the volume of fluid transported. The optimum economic pipe diameter equation (Eq. 17) with nearly uniform resultant velocity values at different flow rates performed better than the standard velocity flow equation (Eq. 20). The second category has four different equations and is used to calculate pipeline pressure drop or pipeline distance for the installation of booster stations after specifying minimum and maximum pipeline pressures. The hydraulic equation is preferred because it gave better resultant velocity values and the closest diameter value obtained using Aspen HYSYS (V.10) simulation. The effect of impurities on the pressure behaviour and optimal pipeline diameter and pressure loss due to acceleration were ignored in the development of the models. Further work is ongoing to incorporate these effects into the models.

scholarly journals Sound, Noise and Speech at the 9000-Seat Holy Trinity Church in Fatima, Portugal

2010 ◽  
Vol 35 (2) ◽  
pp. 145-156 ◽  
Author(s):  
António Carvalho ◽  
Pedro Silva
Keyword(s):  
Sound Pressure ◽  
Measured Data ◽  
Reverberation Time ◽  
Index Method ◽  
Sound System ◽  
Holy Trinity ◽  
Acoustic Quality ◽  
Design Values

Abstract This paper presents the interior acoustical characterization of the 9,000-seat church of the Holy Trinity in the Sanctuary of Fátima, Portugal, inaugurated in 2007. In situ measurements were held regarding interior sound pressure levels (with and without the HVAC equipment working), NC curves, RASTI (with and without the installed sound system) and reverberation time. The results are presented and commented according to the design values. A comparison is made with other churches in the world, also with a very large volume (for instance the Basilica Mariacka in Gdańsk). The measured data are also used to calculate a global index of this church acoustic quality using Engel's and Kosała's Index Method.

Two-step computational aeroacoustics approach for underhood cooling fan application

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.

Clinical oxygen transfer comparison of the Terumo Capiox SX18 and SX25 membrane oxygenators

Perfusion ◽  
1998 ◽  
Vol 13 (2) ◽  
pp. 119-127 ◽  
Author(s):  
David W Fried ◽  
Theodore L Zombolas ◽  
Joseph J Leo ◽  
Hasratt Mohamed ◽  
Gabriel J Mattioni
Keyword(s):  
Pressure Drop ◽  
Oxygen Transfer ◽  
Membrane Surface ◽  
Shunt Fraction ◽  
Flow Rates ◽  
Membrane Surface Area ◽  
Blood Flows ◽  
Side Pressure ◽  
Membrane Oxygenators ◽  
Better Than

The purpose of this current study was to compare the Terumo Capiox SX18 (1.8 m2) with the recently released Capiox SX25 (2.5 m2). Specifically, their oxygen transfer slopes, degree of blood shunting, extrapolated maximum oxygen transfer, blood side pressure drop and oxygen transfer consistency were compared. The lower intercept value (0.209 vs 0.236) coupled with the flatter slope (0.00171 vs 0.00225) of the oxygen transfer line for the SX25 is consistent with improved oxygen transfer performance. A lower FiO2 value would be predicted for the SX25, to achieve a specific PaO2 value, when the oxygen transfer requirement is equal for both devices. Extrapolated maximum oxygen transfer for the SX25 (462.6 ml O2/min) was 36.2% higher than that for the SX18 (339.6 ml O2/min). When indexed to membrane surface area, the SX18 (188.7 ml O2/m2/min performed 2.0% better than the SX25 (185.0 ml O2/m2/min). Both the slope (3.110 vs 3.744) and the intercept (4.595 vs 6.223) of the shunt fraction line were lower for the SX25, indicating that a lower shunt fraction would be predicted for all clinical blood flow rates. The slope (23.934 vs 22.443) and intercept values (-28.388 vs -22.650) of the pressure drop lines for the two devices indicate that the blood side pressure drop, over the range of clinical blood flows, were within 2% of each other. Oxygen transfer consistency, when expressed as the standard deviation of the oxygenator performance index and the percentage of predicted shunt, was not statistically different for the two devices.

scholarly journals Prediction and Reduction of Aerodynamic Noise of the Multiblade Centrifugal Fan

2014 ◽  
Vol 6 ◽  
pp. 712421 ◽  
Author(s):  
Shuiqing Zhou ◽  
Jun Wang
Keyword(s):  
Flow Field ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Low Noise ◽  
Aerodynamic Noise ◽  
Hybrid Technique ◽  
Field Calculation ◽  
Pressure Amplitude ◽  
Centrifugal Fan ◽  
Hybrid Techniques

An aerodynamic and aeroacoustic investigation of the multiblade centrifugal fan is proposed in this paper, and a hybrid technique of combining flow field calculation and acoustic analysis is applied to solve the aeroacoustic problem of multiblade centrifugal fan. The unsteady flow field of the multiblade centrifugal fan is predicted by solving the incompressible Reynolds-averaged Navier-Stokes (RANS) equations with conventional computing techniques for fluid dynamics. The principal noise source induced is extracted from the calculation of the flow field by using acoustic principles, and the modeled sources on inner and outer surfaces of the volute are calculated with multiregional boundary element method (BEM). Through qualitative analysis, the sound pressure amplitude distribution of the multiblade centrifugal fan in near field is given and the sound pressure level (SPL) spectrum diagram of monitoring points in far field is obtained. Based on the analysis results, the volute tongue structure is adjusted and then a low-noise design for the centrifugal fan is proposed. The comparison of noise tests shows the noise reduction of improved fan model is more obvious, which is in good agreement with the prediction using the hybrid techniques.

A Comparison of Measurement Standard Methods for the Sound Insulation of Building Façades

2012 ◽  
Vol 19 (4) ◽  
pp. 267-282 ◽  
Author(s):  
Umberto Berardi
Keyword(s):  
Sound Pressure ◽  
External Source ◽  
National Standards ◽  
Sound Insulation ◽  
Reverberation Time ◽  
Measurement Standard ◽  
Low Frequencies ◽  
Standard Methods ◽  
Building Facades ◽  
Future Version

This paper focuses on the limits of measurement of the sound insulation of building façades at low frequencies. Three standard methods are compared mainly for the position of the equipment. In particular, the positions proposed by the international standard ISO 140-5 and the national standards ASTM E 966 (USA) and JIS A 1430 (Japan) are considered. The limits of measurement of the sound pressure level in front of the façade are investigated. Different placements of the external source and receiver are considered. Moreover, different placements of the receiver inside small rooms are compared by focusing on corner vs. center room positions. The uncertainties of room averaged sound pressure levels measured according to different standards are discussed. The problems of measurement of the reverberation time in small rooms and of sound insulation in irregular shaped rooms are introduced because these measurements present several critical challenges. Finally, suggestions to improve the future version of the ISO 140-5 are reported.

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