Marine engine external exhaust noise suppressor with swim platform

In this paper, we demonstrate how to reduce the noise level of expanded air from pneumatic tools. Instead of a muffler, we propose the expanded collecting system, where the air expands through the pneumatic tube and expansion collector. We have elaborated a mathematical model which illustrates the dynamics of the air flow, as well as the acoustic pressure at the end of the tube. The computational results were compared with experimental data to check the air dynamics and sound pressure. Moreover, the study presents the methodology of noise measurement generated in a pneumatic screwdriver in a quiet back room and on a window-fitting stand in a production hall. In addition, we have performed noise measurements for the pneumatic screwdriver and the pneumatic screwdriver on an industrial scale. These measurements prove the noise reduction of the pneumatic tools when the expanded collecting system is used. When the expanded collecting system was applied to the screwdriver, the measured Sound Pressure Level (SPL) decreased from 87 to 80 dB(A).

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A Numerical Study on the Combustion Process and Emission Characteristics of a Natural Gas-Diesel Dual-Fuel Marine Engine at Full Load

Energies ◽

10.3390/en14051342 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1342

Author(s):

Van Chien Pham ◽

Jae-Hyuk Choi ◽

Beom-Seok Rho ◽

Jun-Soo Kim ◽

Kyunam Park ◽

...

Keyword(s):

Natural Gas ◽

Combustion Process ◽

Simulation Software ◽

Dual Fuel ◽

Injection Timing ◽

Emission Characteristics ◽

Cylinder Pressure ◽

Marine Engine ◽

Full Load ◽

Simulation Results

This paper presents research on the combustion and emission characteristics of a four-stroke Natural gas–Diesel dual-fuel marine engine at full load. The AVL FIRE R2018a (AVL List GmbH, Graz, Austria) simulation software was used to conduct three-dimensional simulations of the combustion process and emission formations inside the engine cylinder in both diesel and dual-fuel mode to analyze the in-cylinder pressure, temperature, and emission characteristics. The simulation results were then compared and showed a good agreement with the measured values reported in the engine’s shop test technical data. The simulation results showed reductions in the in-cylinder pressure and temperature peaks by 1.7% and 6.75%, while NO, soot, CO, and CO2 emissions were reduced up to 96%, 96%, 86%, and 15.9%, respectively, in the dual-fuel mode in comparison with the diesel mode. The results also show better and more uniform combustion at the late stage of the combustions inside the cylinder when operating the engine in the dual-fuel mode. Analyzing the emission characteristics and the engine performance when the injection timing varies shows that, operating the engine in the dual-fuel mode with an injection timing of 12 crank angle degrees before the top dead center is the best solution to reduce emissions while keeping the optimal engine power.

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Measurement of Noise inside the Compartment and Vibration on both Sides of Elastomeric Powertrain Mounts of Passenger Car

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.471.59 ◽

2013 ◽

Vol 471 ◽

pp. 59-63

Author(s):

Mohd Noor Arib Rejab ◽

Roslan Abd Rahman ◽

Raja Ishak Raja Hamzah ◽

Jawaid Iqbal Inayat Hussain ◽

Nazirah Ahmad ◽

...

Keyword(s):

Fast Response ◽

Sound Level ◽

Measurement Noise ◽

The Other ◽

Vibration Level ◽

Test Conditions ◽

Exhaust Noise ◽

Run Up ◽

Level Meter ◽

High Level

This paper presents an evaluation on elastomeric mount used to isolate vibration from powertrain to chassis or structure vehicle. The assessments started with measurement of noise inside compartment, and exhaust noise. This is followed by the measurement of vibration on both sides of elastomeric mounts. The noise in the compartment and exhaust noise is measured according to BS 6086: 1981 and BS ISO 5130: 2007. The noise in the compartment and vibration is tested in three conditions. Firstly, engine is run-up with load (driving at second gear); secondly, without load; and thirdly, without load but hanging. A microphone is fixed at the ear of the mannequin. The fast response and A weighting sound level meter were used for measurement noise in the compartment and exhaust noise. The vibration is measured in terms of acceleration on both sides of each elastomeric powertrain mounts. Two accelerometer transducers are fixed on both sides of powertrain elastomeric mounts. One side was identified as a source of vibration and the other as receiver of vibrations. The results showed that the pattern of overall vibration level on source and receiver increased from 1050 RPM (idling) to 4000 RPM on all test conditions. Vibration transmitted to chassis or receiver structure was analyzed using transmissibility concept. By evaluating test condition of engine run-up without load, informed that the front and rear mounts showed a high level transmissibility contributing to structure-borne noise.

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Acoustic Source Data for Medium Speed IC-Engines

Journal of Vibration and Acoustics ◽

10.1115/1.4006415 ◽

2012 ◽

Vol 134 (5) ◽

Cited By ~ 5

Author(s):

Antti Hynninen ◽

Raimo Turunen ◽

Mats Åbom ◽

Hans Bodén

Keyword(s):

High Frequency ◽

Internal Combustion Engines ◽

Low Frequency ◽

Acoustic Source ◽

Ic Engine ◽

Source Characteristics ◽

Medium Speed ◽

Source Data ◽

Exhaust Noise ◽

Ic Engines

Knowledge of the acoustic source characteristics of internal combustion engines (IC-engines) is of great importance when designing the exhaust duct system and its components to withstand the resulting dynamic loads and to reduce the exhaust noise emission. The goal of the present study is to numerically and experimentally investigate the medium speed IC-engine acoustic source characteristics, not only in the plane wave range but also in the high frequency range. The low frequency acoustic source characteristics were predicted by simulating the acoustic multiload measurements by using a one-dimensional process simulation code. The low frequency in-duct exhaust noise of a medium speed IC-engine can be quite accurately predicted. The high frequency source data is estimated by averaging the measured acoustic pressures with different methods; using the simple cross-spectra averaging method seems promising in this instance.

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