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박호일(Hoil Park),서주봉(Jubong Seo),홍성유(Sungyou Hong),강수영(Suyoung Kang),김장균(Janggyeun Kim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
A flow noise radiating from a compressor housing of a vehicle turbocharge was investigated. The noise was induced by a vortex around the intake area of the compressor wheels - a intake flow noise, realized to be largely affected by a combination of the shape of the compressor scroll and that of compressor wheels by tests. And, its frequency did not increase proportionally to the turbocharger speed, and was located around the range of 1.6㎑ and 1.8㎑ to the whole working area of the turbocharger. Some countermeasures were tried to reduce the noise - helmholtz resonators, the change of the diffuser, the smaller compressor scroll, and a groove around the intake area of the compressor wheels. The smaller compressor scroll could effectively reduced the noise, but was not adopted because of the deterioration of the compressor performance. For the noise reduction, the groove was chosen because it could sufficiently reduce the noise and maintain the performance.
박호일(Hoil Park),엄상봉(Sangbong Eom),황준영(Junyoung Hwang),윤태진(Taejin Yoon) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
A noise map has been developed for globally analyzing special noises radiating from automotive turbochargers. This map could be obtained by replacing the efficiency with noise data in a compressor performance map. The characteristics of a special noise could be easily understood from it since the noise distribution was shown on their operating area. Turbochargers were generally operated under constant speeds for measuring their performance. This paper compared two additional operation modes to the constant speed for the noise map. First, it was operated for almost constant volumetric flow rates in a compressor. Second, it was done for constant pressure ratios. In addition, it was investigated how the maps would be changed by the different sweeping times of surge-to-choke at the constant speeds, 1/2 and 1/4 times of the reference period.
박호일(Hoil Park),김형진(Hyungjin Kim),강수영(Suyoung Kang),엄상봉(Sangbong Eom) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
A noise map drawing technology was developed for analyzing noises radiating from turbochargers of vehicles engines. The map was obtained by superposing turbocharger noise data onto a compressor performance map. The characteristics of a special noise could be easily understood with it since the noise distribution was shown on the turbocharger operation area. It was shown on the map for the turbocharger of a passenger car engine that the special noise were abruptly increased over a certain turbocharger speed, and the range of the high level noise became wider as the speed increased. It was possible to analyze engine operation area causing the turbocharger noise problem by plotting an engine operation line to the noise map. Furthermore, the map could propose a proper engine operation line not causing the noise problem by comparing it and turbocharger noise contours. This paper showed that a turbocharger noise problem could be solved by limiting an engine operation line with the turbocharger noise map and the line plotted on the map.
박호일(Hoil Park),최성배(Sungbae Choi),장성식(Seongsik Jang),황준영(Junyoung Hwang) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
There are several flow noises induced from compressors of automotive turbochargers. In the previous study, the flow noise was analyzed to be around 1.6k~1.8kHz from gasbench tests, and could be reduced by machining a proper rectangular groove around compressor inlet before its main blades. The groove was shown to be very effective for removing the noise under the small difference of compressor performance. It was all right because the engine performance was high enough to cover the difference. This study was interested in another flow noise, rather the higher and wider frequency band, 4k~6kHz ? the 3<SUP>rd</SUP> order of turbocharger speed, and proposed an optimal configuration of the groove, lowering the noise and maintaining the performance. A best shape was proposed, and was confirmed to be satisfied with the performance on an engine dynamometer and the noise target on a vehicle.
박호일(Hoil Park),임상봉(Sangbong Eom),서주봉(Jubong Seo),이승현(Seunghyun Lee) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4
Automotive turbochargers have become common in gasoline engines as well as diesel engines. They are excellent devices to effectively increase fuel efficiency and power of the engines, but they unfortunately cause several noise problems. The noises are classified into mechanical noises induced from movement of a rotating shaft and aerodynamic noises by air flow in turbochargers. The mechanical noises are whine and howling noises, and the aerodynamic noises are BPF (blade-passing frequency), pulsation, surge, some special frequency noises. These noises are bothering passengers because their levels are higher or their frequencies are clearly separated from engine or vehicle noises. The noise investigated in this paper is a BPF noise induced by compressor wheels, whose frequency is the multiplication of the number of compressor wheel blades and its rotational speed. The noise is strongly dependent upon the geometry of wheels and the number of blades. This study tried to apply a groove close to the inlet side of compressor wheels in order to reduce the BPF noise. The groove has successfully reduced the noise of narrow band frequency of a turbocharger. It shows that the groove could reduce the wide band frequency noise, the compressor BPF noise with a best shape of the groove.