Добірка наукової літератури з теми "Racing Motors Exhaust systems Noise"

Most buildings such as hospitals, hotels, governmental offices, data processing rooms, etc, are equipped with internal combustion engines, diesel motors and generators to supply energy in emergencies. These same IC engines are used for industrial applications, building services and transportation. Exhaust noise are the predominant noise source with most internal combustion engines and thus exhaust systems incorporating mufflers have been designed to reduce the noise. This paper describes the analysis of several configurations of mufflers and also presents comparisons between the results for the transmission loss obtained by numerical modelling (FEM), Transfer Matrix Method (TMM) and measurements.

The article presents the results of developing and evaluating the effectiveness of the silencer of outboard motor SEA PRO 2.5 made in China. The experiments were carried out in a large experimental pool of Astrakhan State Technical University, with the use of a noise meter-spectrum analyzer Ecophysics-110 of the first class, with the software Signal+3G Light. In the theoretical analysis of the development, it has been suggested that the efficiency of silencers of exhaust systems of outboard motors could have a smaller effect than with cars, since at underwater exhaust the noise reduction will occur from the water layer when the motor is submerged. It has been proved that using a silencer in underwater exhaust systems of outboard motors can increase the aerodynamic drag for gases and reduce power. To test the theoretical assumptions, there was made a silencer for the gas exhaust system of the outboard motor SEA PRO 2.5 from stainless steel perforated sponge. It was determined that the net effect of the silencer (excluding water silencing) could be heard at low frequencies (up to 125 Hz) and makes up to 12.7 dba at full speed of the motor. The average equivalent sound level is reduced up to 4.5 dba at low speed, and at full speed of the outboard motor is practically not evident. In addition, the outboard motor noise level was reduced by water and made at full speed up to 22 dba for frequencies over 2000 Hz; for average equivalent noise level it made 15 dba. The combination of noise reduction by water and by a silencer helps to reduce noise at low and high sound frequencies, which is a positive effect of the developed device.

Abstract The development and growing availability of modern technologies, along with more and more severe environment protection standards which frequently take a form of legal regulations, are the reason why attempts are made to find a quiet and economical propulsion system not only for newly built watercraft units, but also for modernised ones. Correct selection of the propulsion and supply system for a given vessel affects significantly not only the energy efficiency of the propulsions system but also the environment - as this selection is crucial for the noise and exhaust emission levels. The paper presents results of experimental examination of ship power demand performed on a historic passenger ship of 25 m in length. Two variants, referred to as serial and parallel hybrid propulsion systems, were examined with respect to the maximum length of the single-day route covered by the ship. The recorded power demands and environmental impact were compared with those characteristic for the already installed conventional propulsion system. Taking into account a high safety level expected to be ensured on a passenger ship, the serial hybrid system was based on two electric motors working in parallel and supplied from two separate sets of batteries. This solution ensures higher reliability, along with relatively high energy efficiency. The results of the performed examination have revealed that the serial propulsion system is the least harmful to the environment, but its investment cost is the highest. In this context, the optimum solution for the ship owner seems to be a parallel hybrid system of diesel-electric type

The purpose of the present study is to improve the on-street exhaust noise measurement technique for regulating vehicles that emit unacceptably large exhaust noise. The method under development uses racing operation of engines with a wide-open throttle on a standing vehicle. In contrast, the engine operation condition considered in the conventional on-street measurement technique considers operation at 75% of rated power followed by the throttle valve being released to its original position. The current regulation considers the maximum noise level during this engine operation condition. Accordingly, the engine is not loaded during testing. This loading condition provides unsatisfactory correlation between the exhaust noise level measured by the on-street method and the ISO vehicle acceleration noise under the wide-open throttle condition. The present paper reports the advantages of the proposed method as well as some important factors in the proper application of the newly proposed method. In the present study, we perform noise measurement along highways, a vehicle experiment in an anechoic chassis dynamometer, and computer simulations. The results revealed that the proposed on-street measurement method can be used to approximately determine the exhaust noise level during full acceleration for most vehicle types. In addition, the sensitivities of the measured noise levels for the testing conditions were clarified. The second item in this study is efficient engine speed measurement using exhaust sound signal only without electric wire harnessing. A survey of the measurement systems proposed by three different companies revealed that the measurement principles of two of these systems have potential application to on-street exhaust measurement. The last item investigated herein is better indices of exhaust noise evaluation. Loudness defined by ISO was found to be much better than the conventional dB(A) scale in terms of correlation with subjective evaluation results.