Wyniki wyszukiwania - BazTech

1

Evaluation of vibration and noise characteristics of a compression-ignition engine fuelled with natural gas-biodiesel dual fuel

Stravinskas Saulius, Rimkus Alfredas, Matijošius Jonas

Transport Problems

|

2023

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T. 18, z. 1

67--74

EN

As environmental requirements become more stringent and the planet becomes more polluted, the replacement of conventional diesel is attracting more interest. For alternative fuels, such as biodiesel and natural gas, to be used, their effects must be examined not only in terms of the engine’s environmental indicators but also in terms of engine vibrations and sound pressure. This study examined the influence of dual fuel – biodiesel and natural gas – on vibrations and sound pressure of a compression-ignition (CI) engine. Conventional diesel or hydrotreated vegetable oil biodiesel was used as a pilot fuel for gas ignition. The gaseous fuel was natural gas, which was injected into the intake manifold with different energy shares of the gaseous fuel (40%, 60% and 80%). Tests were performed at a constant engine crankshaft speed and a fixed start of pilot fuel injection of 6° BTDC while the fuel composition and engine load were changed. This experiment revealed correlations between gas energy share (GES) in liquid fuel and ecological and energy indicators of a CI engine.

2

Impact of gear rim narrowing angle on the temperature and sound pressure of Beveloid gear pair made of polymeric materials

Strojny Piotr

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

|

Vol. 69, nr 5

art. no. e138818

EN

The paper contains a description of the geometry of Beveloid gears. It describes the distribution of forces in a Beveloid gear with a straight tooth line and a helical tooth line. The paper presents research on the experimentally determined parameters of transmission operation, including the sound pressure level and the amount of heat emitted during operation. The design and construction of the test stand were presented. The research methodology was described. Operational tests are carried out on household appliances with Beveloid gears: Grinder and Jam mixer. Thanks to an appropriately selected narrowing angle, estimated values of service life extension of the above-mentioned transmissions are given.

3

Acoustic analysis of selected sacred buildings in Szczecin

Stolarska Agata, Strzałkowski Jarosław, Kandybowicz Agata

Budownictwo i Architektura

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2021

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Vol. 20, no 4

17--35

EN

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.

4

Power affects to the sound pressure of a four-stroke engine

Kilikevičienė Kristina, Kilikevičius Artūras, Matijošius Jonas, Rimkus Alfredas

Archiwum Motoryzacji

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2019

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Vol. 86, nr 4

143--150

EN

The noise generated by the four-stroke S320 Andoria internal combustion engine is a complex field of study because the total sound pressure is the sum of the sound pressures produced by each engine component. The noise level and sound frequency of diesel engines used in agricultural machinery are highly dependent on fuel combustion. The standard diesel fuel conforming to EN 115 was used in the tests. Sound pressure was measured with the Bruel & Kjear equipment. Investigations show the dynamics of the dynamic parameters of the four-stroke engine, which must be evaluated when operating agricultural machinery. Experimental research of power influence on sound pressure of four-stroke diesel engine was performed. The dependence of the sound pressure level on the variation of the motor power was determined. Studies have shown that as the engine power increases from 2.63 to 9.48 kW, the sound pressure standard deviation increases by about 0.041 Pa.

5

Monitoring of the Noise Emitted by Machine Tools in Industrial Conditions

Józwik J., Wac-Włodarczyk A., Michałowska J., Kłoczko M.

Journal of Ecological Engineering

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2018

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Vol. 19, nr 1

83--93

EN

The paper presents an analysis of noise emitted by selected machine tools in a production hall (under industrial conditions). Noise monitoring is a fundamental task for maintaining workplaces which are safe and healthy. This paper presents the noise measurements obtained for several machine tools, performed in accordance with the PN ISO 230–5:2002 standard. The identification of noise sources and levels was conducted by means of the UNIT 352 measurement system for DMU 50, BGO-CNC/RV/R, FU 251, FW 801, FWC 25/H. Detection of noise sources in the tested machine tools allows to maintain safety of workers and effective means of noise reduction, which are highly significant from the perspective of minimising noise at various workstations. The method of performing noise measurements at workstations using specific machines is normalised, so that the results of such measurements for different machines could be compared. The test results were presented in the form of diagrams and tables. The results of the tests are concluded by a detailed recommendation for the CNC machine tool operators to use hearing protection when at work. The results showed that the level of noise at the operator’s workstation significantly exceeds the standard at certain machining parameters.

6

Sound Radiation by a Cylindrical Open Cavity with a Surface Source at the Bottom

Szemela K.

Archives of Acoustics

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2018

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Vol. 43, No. 1

49--60

EN

The rigorous solution describing the sound radiation by an arbitrary surface source located at the bottom of a cylindrical open cavity embedded in a flat baffle has been obtained. The open cavities of different shapes can be found in some architectural structures as well as are components of sensors, musical instruments and vehicles. The presented formulas have been expressed in the form of Infinite sums. To use them, the infinite sums have to be truncated to the finite number of terms. Therefore, in practice, the results obtain based on the proposed solution are not exact and their accuracy is determined by the truncation error. The use of presented formulas is an alternative method for the finite element method (FEM). However, taking into account that the calculation efficiency of FEM rapidly decrease when a volume of considered region increases, the obtained in this study solution can be more useful in some practical cases. The approximated formula of a high computational efficiency has been presented for the sound pressure in the far field. The sound radiation has been analyzed for a rectangular piston as a sound source. The influence of cavity depth ratio on the radiation efficiency has been investigated. The cases for which the cavity radiation efficiency can be approximately calculated from the formula valid for a baffled sound source have been determined.

7

Podstawowe pojęcia akustyczne

Nowoświat A., Dulak L.

Izolacje

|

2016

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R. 21, nr 1

28--32

PL

W artykule wytłumaczono podstawowe pojęcia z akustyki budowlanej. Wprowadzono pojęcia miar amplitudowych i względnych. Pokazano, jak sumować źródła hałasu. Wprowadzono także zagadnienie analizy widmowej.

EN

The article explains the key concepts of sound and acoustics in construction. Amplitude and relative measures are introduced. The method of summarizing sources of noise is presented. In addition, there is presentation of spectral analysis.

8

Modele dynamiczne rozkładu poziomu dźwięku wewnątrz kabin lokomotyw spalinowych SM42

Komorski P., Szymański G. M.

Logistyka

|

2015

|

nr 4

4130--4136, CD2

PL

W artykule przedstawiono analizę propagacji hałasu wewnątrz kabin maszynistów lokomotyw spalinowych serii SM42. Przeprowadzono badania polegające na pomiarach poziomów ciśnienia akustycznego we wnętrzu wybranych typów pojazdów szynowych. Pomiary były wykonywane podczas postoju pojazdu z włączonym silnikiem oraz podczas jazdy manewrowej. Na podstawie przeprowadzonych badań i założeń metody niestacjonarnej transformacji przestrzennej pola dźwiękowego (STSF), opracowano modele dynamiczne rozkładu poziomówciśnienia akustycznego. Analiza modeli dynamicznych polegała na prezentowaniu poszczególnych map akustycznych przedstawiających rozkład poziomów ciśnienia akustycznego w kabinach lokomotyw. Przedziałom poziomów dźwięku były przyporządkowane odpowiednie gamy barw.Celem badań byłaanaliza zmian wartości chwilowych i średnich poziomów dźwięku wewnątrz kabin oraz ustalenie źródeł hałasu w pojazdach.

EN

The article presents an analysis of noise propagation inside the driver's cab internal combustion locomotives series SM42. The research consisted on measurements sound pressure levels in several selected types of rail vehicles. The measurements were carried out in two different situation; while vehicles idling and shunting. Based on measurements and the main assumptions of non-stationary spatial transformation of sound field (STSF) method, several dynamic model of sound propagation were elaborated.Analysis of dynamic models was based on presenting the acoustic maps which are showing the distribution of the sound pressure levels in the cabs of locomotives. Compartments of the sound levels were assigned to the appropriate range of colors. The aim of the research was to analyze the changes in the instantaneous and average sound pressure levels inside the vehicles and identify the sources of noise in internal combustion locomotives.

9

Sound Radiation from a Surface Source Located at the Bottom of the Wedge Region

Szemela K.

Archives of Acoustics

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2015

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Vol. 40, No. 2

223--234

EN

Applying rigorous analytical methods, formulas describing the sound radiation have been obtained for the wedge region bounded by two transverse baffles with a common edge and bottom. It has been assumed that the surface sound source is located at the bottom. The presented formulas can be used to calculate the sound pressure and power inside the wedge region. They are valid for any value of the wedge angle and represent a generalization of the formulas describing the sound radiation inside the two and three-wall corner region. Moreover, the presented formulas can be easily adapted for any case when more than one sound source is located at the bottom. To demonstrate their practical application, the distribution of the sound pressure modulus and the sound power have been analyzed in the case of a rectangular piston located at the wedge’s bottom. The influence of the transverse baffle on the sound power has been investigated. Based on the obtained formulas, the behaviour of acoustic fields inside a wedge can be predicted.

10

Izolacyjność akustyczna ścian w salkach do prób w szkole muzycznej

Zastawna-Rumin A., Zębala K.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

|

2014

|

z. 61, nr 3/II

531--540

PL

W artykule zawarto wyniki badań izolacyjności akustycznej przegród w salach do prób w szkole muzycznej. Analiza wyników przeprowadzona została w odniesieniu do aktualnych przepisów oraz w aspekcie odczuwania komfortu. Aby sprawdzić, czy ujęte w normach wymagania dotyczące izolacyjności przegród w szkołach są wystarczające, aby komfortowo uczyć się gry na instrumentach, dokonano pomiarów izolacyjności akustycznej ścian i drzwi w salkach do prób w jednej ze szkół muzycznych. Kolejnym elementem analizy w aspekcie izolacyjności akustycznej było określenie wpływu przedsionka na warunki akustyczne w salach prób. Izolacyjność akustyczna zarówno ścian pomiędzy salami jak i ścian z drzwiami prowadzącymi do przedsionka spełniają wymagania dotyczące izolacyjności od dźwięków powietrznych ale tylko w odniesieniu do szkół tradycyjnych. Pomimo spełnienia warunków dotyczących izolacyjności od dźwięków powietrznych dla ścian analizowanych pomieszczeń, komfort akustyczny w tych salach nie jest wystarczający. Obserwacje oraz wywiad z użytkownikami sal wskazuje na wzajemne zakłócenia dźwięków w przypadku jednoczesnego korzystania z sąsiadujących sal. Autorzy artykułu postulują zatem konieczność stworzenia takich wymagań normowych, aby szkoły muzyczne i inne temu podobne instytucje, zapewniały komfort nauki gry na instrumentach i śpiewu. W analizowanym budynku szkoły muzycznej zaprojektowanie przedsionków było właściwym rozwiązaniem, skutkującym znacznym zwiększeniem izolacyjności od dźwięków powietrznych generowanych na korytarzu. Ochrona od dźwięków generowanych w sąsiedniej sali jest zbyt niska – nie stwarza warunków komfortowych do nauki muzyki. Sytuacja, w której każda sala posiadałaby oddzielny przedsionek, byłaby rozwiązaniem bardziej korzystnym.

EN

The article contains the results of acoustic tests of the insulation provided by the barriers located in a rehearsal room of the music school. The analysis of the results was carried out in relation to the current legislation and to the relative comfortable feeling. To check whether the requirements for the barrier insulation that are included in the standards are sufficient for the comfortable learning to play instruments, measurements were made of sound insulation of the walls and doors in the rehearsal hall in one of the music schools. Another element of the analysis in aspect of sound insulation was to determine the effect of the atrium on the acoustic rehearsal rooms. The sound insulation in both the walls between the rooms and the walls with a door leading to the vestibule meet all the requirements for airborne sound insulation but only in relation to traditional schools. Despite the fact that the airborne sound insulation of the walls in the rooms fulfilled the requirements of the standards, the acoustic comfort in these rooms was not preserved. The observations and the interview with room occupants have shown the presence of sound disruptions in cases where adjacent rooms are simultaneously used. Therefore, there is a need to define standards for music schools and other similar institutions, in order to provide comfort to learn to playing instruments and singing. In the music school where the investigations were conducted, the creation of a vestibule in each room was the right solution that significantly increased the insulation from the airborne sound generated in the hallway. The protection against the sounds generated in the adjacent rooms is too low – it does not ensure comfortable conditions for learning music. If every room had its separate vestibule, the situation would look much better.

11

Zastosowanie metod MLS i Swept Sine do pomiarów akustycznych w warunkach wysokiego tła akustycznego

Tomczyk P.

Prace Instytutu Techniki Budowlanej

|

2010

|

R. 39, nr 4

27-52

PL

Przedstawiono ogólne informacje na temat metod pomiarowych z wykorzystaniem odpowiedzi impulsowej, opisano wymagania nowych metod pomiarowych oraz podano wyniki pomiarów przeprowadzonych z zastosowaniem nowych technik (MLS, Swept Sine), a także dokonano porównania wyników otrzymanych przy użyciu nowych technik z wynikami otrzymywanymi metodami klasycznymi.

EN

This paper includes general information on measurement methods with the use of impulse response. Requirements concerning new measurement techniques have been described and results of measurements conducted using new methods (MLS, Swept Sine) have been presented. Results achieved by the use of new techniques and those achieved by classical methods have been compared.

12

Acoustic power radiated into the quarter-space by a circular membrane with an asymmetric excitation

Rdzanek W. P., Rdzanek W. J., Szemela K.

Archives of Acoustics

|

2009

|

Vol. 34, No. 1

75-94

EN

A circular membrane excited asymmetricaly is vibrating and radiating acoustic waves into the quarter-space limited by two rigid baffles arranged perpendicularly to one another. These processes are time harmonic. The classical Neumann boundary value problem has been solved using the complete eigenfunctions system together with the corresponding coupling matrix and including the acoustic attenuation effect.

13

Weld transference modes identification through sound pressure level in GMAW process

Cayo E. H., Absi Alfaro S. C.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

|

Vol. 29, nr 1

57-62

EN

Purpose: One of the most used processes in the industry is GMAW, in this welding process there is physical phenomena such as the temperature, electromagnetic field, luminosity and sound pressure. It is known that GMAW weld specialized techinicisian combine visual and sound at the work to garantee the process stability. It is important to improve the final weld quality; therefore, the quantification of electrical and acoustical behaviour-within the audible bands, offer an information that is important to comprehend his impirical rules. Design/methodology/approach: With these he can identify the transfer mode, instabilities in the process, determine defects and evaluate the weld quality along the weld bead. The sound signal is captured simultaneously with the arc voltage and current signals. Was proved that first derived from the instantaneous power of the electrical arc presents a behaviour similar to the acoustical with a delay, because the measured sound is airborne. Findings: This relation was corroborated by the comparison between the sound pressure level calculated by electrical signals and by acoustical signals. This relation presented a similarity between the calculated signals greater than that between the sound and the power first derived. Practical implications: Besides that, with the sound pressure level it is possible to identify process instabilities that is not so trivial to realize with the sound pressure signal. In spite of it, the identification of instabilities for the globular and spray tranfer modes displays greater difficulty than that for the short circuit transfer mode. It was shown that the acoustical weld sensing offers information about the behaviour of the tranfer mode and the process stability. Originality/value: The sound quantification would be applied as a control variable for the weld process. Thus, it would be possible to develop similar control strategies as those applied by specialized workers.

14

Sound pressure radiation of a circular piston located at a two- and three-wall corners

Rdzanek W. P., Szemela K., Pieczonka D.

Archives of Acoustics

|

2007

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Vol. 32, No. 4

883--893

EN

This paper focuses on the far eld approximation of the steady state sound pressure radiated by a at circular piston into the region bounded by some at rigid bafes. The two Neumann boundary value problems have been considered for the regions of two- and three-wall corners, separately. The Green function in its Fourier representation has been used together with the Sommerfeld radiation condition which has given the sound pressure approximation in the form of some useful elementary formulations. The boundary value problems often appear in the situation when the sound source is located in the vicinity of the Earth and some vertical walls, e.g. the sound barriers, the building walls, etc.

15

Numerické modelování šířeni hluku

Biskup M.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

|

2002

|

z. 19

13-16

EN

This paper is concerned in modeling of noise propagation of a small end-fixed plate. The excitation was harmonic in range of audibility region. The modeling of noise propagation is made in MATLAB r.6. The noise propagation is calculated in ANSYS 5.7 because of comparing. The analysis of size of acoustic field in effect on a sound pressure level in case of model without boundary elements in the border of acoustic field is made.