Sound power is one of the most important elements to predict and evaluate the noise emitted from the noise sources. But it has been used developing the indirect method to calculate the sound power by using the sound pressure levels measured by lots of...
Sound power is one of the most important elements to predict and evaluate the noise emitted from the noise sources. But it has been used developing the indirect method to calculate the sound power by using the sound pressure levels measured by lots of researchers because it is impossible to measure the sound power directly during the running of rolling stock. This method, however, is not considered the emission characteristics for each type of noise sources so, it should calculated the sound power considering the emission characteristics for each type of noise sources in order to calculate the precise value of the sound power emitted from the noise sources. This thesis measured the running noise of EMU, Mugunghwa, KTX trains operating domestically, selected the propulsion noise and rolling noise among the main noises in the whole noises emitted from rolling stocks, suggested the way to assume the sound power reflecting the emission characteristics and modelling suitable for each rolling stock characteristics, checked out the validity through the comparison of the assumption method, and concluded the following results next below.
Rolling noise depending on the contact between wheel and rail modeling as the form of point source listed continuously noise source for rolling stock and the propulsion noise depending on the propulsion equipment such as engines & motors are separated and then we suggested the way to assume the sound power about each type of noise source considering the emission characteristics for each noise source.
As a result of the calculation of the sound power about the domestic rolling stocks using the assumption method of sound power suggested by this study, we figured it out that the sound power was ranked by Mugunghwa, EMU, KTX in sequence in the range of the same speed. The reason why was the sound power of diesel engine was bigger than electric propulsion equipment like motor block and the rolling stock structure & design difference just like the main cause of the rolling noise such as the number of bogies and difference of suspension was analyzed.
As a result of the sound power, Mugunghwa train has big propulsion noise emitted from diesel engine compared to rolling noise, KTX train has the big propulsion noise since the sound power of motor block compared with diesel engine is low relatively and has a number of noise sources of propulsion.
We checked it out that the sound power considering the moving effect of noise sources while high speed rolling stock like KTX was running at the rate of 300km/h should be calculated and then the results are united.
Using the noise measurement of domestic rolling stocks & analysis result, this study showed the validity of the assumption method of the sound power showing the identical result after reviewing the calculation method of sound power according to the assumption method of the sound power suggested and foreign experience.