고속 평면제트에 의한 쐐기음의 특성 연구

권영필,이근희,장욱,김욱,Kwon, Young-Pil,Lee, Geun-Hee,Jang, Wook,Kim, Wook 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.12

The impinging tones by high-speed plane jets are experimentally investigated to study the edgetone characteristics. Experiment used a slit nozzle and a wedge system to generate edgetones. The jet in the experiment is varied from low to high subsonic speed to obtain the effect of the speed on the frequency characteristics of impinging tones. The experimental data obtained previously fur edgetones and platetones by various nozzles are compared with the present edgetone data. And the condition of tone generation, the frequency ranges, the effective source point and the sound pressure level are compared and discussed. It is found that the jet speed has no diect influence on the impinging tone characteristics. Regardless of the jet speed, the effective source point is about a quarter wavelength downstream from the edge tip. With increase in jet speed, the influence of the nozzle configuration is decreased and the operating frequencies show good coincidences by normalized parameters based on the slit thickness.

표면 연소기의 연소진동음의 발생조건

권영필,이주원,이동훈,Kwon, Y.P.,Lee, J.W.,Lee, D.H. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.2

A strong combustion-driven sound from a surface burner made of a perforated metal fiber plate for premixed gas was investigated to clarify the physical mechanism of its generation. A simple model was developed for the acoustic power generation in terms of the heat transfer response function and the acoustic impedance of the burner. The acoustic impedance of the perforated metal fiber placed on the open exit was measured and the heat release response of the burner to the oscillating flow associated with the acoustic disturbance was expressed in terms of a response function. It was found that the power is generated by the heat release in response to the downstream particle velocity, in contrast to the upstream velocity in the case of the Rijke oscillation driven by a heater placed in the lower half of a columm with upstream flow. The measured frequencies of the oscillation were in agreement with the estimated resonance frequencies and their excitation was varied with the combustion conditions. For the same fuel rate, the excited frequency increases with the air ratio if it is low but decreases with the ratio if not so low. Such frequency characteristics were explained by assuming a heat release response function with a time constant and it was shown that the excited frequency decreases as the time constant increases.

설비소음제어의 개요

권영필,Kwon, Y.P. 대한설비공학회 1997 설비저널 Vol.26 No.6

단면 변화가 있는 기주의 열음향진동에 관한 연구

권영필,홍하표,Kwon, Young Pil,Hong, Ha Pyo 대한설비공학회 1988 설비저널 Vol.17 No.2

The thermoacoustic oscillation induced in an air column with variable cross section area is investigated theoretically and experimentally. The onset condition of the oscillation is derived by equating the acoustic power production to the power dissipation. The power production at the heater is predicted by using the efficiency factor obtained by heat transfer analysis for a single wire in a uniform cross flow and considering the interference between heater wires. The power dissipation is estimated by measuring the attenuating coefficient from the pressure decay curve. The theoretical prediction to the onset condition of the oscillation is confirmed experimentally. The effect of the variation of the column cross section area on the onset condition is presented.

맥동류에 놓인 구로부터의 열전달

권영필,이계철,Kwon Young-Pil,Lee Kye-Cheul 대한설비공학회 1987 설비저널 Vol.16 No.2

The heat transfer characteristics from a solid sphere in a fluctuating air flow is simulated numerically in the range of the Reynolds numbers, $1\;{\leqslant}\;Re\;{\leqslant}\;40.$ Such a situation may be encountered in forced convection from a heated spherical particle in a sound field or oscillat-ing flow. The amplitude and phase delay in the heat transfer response to the flow oscillation are computed for a small amplitude flow. The instantaneous response of heat transfer is simulated for the large amplitude oscillation and compared with the quasi-steady response. The effect of the oscillation on the time - mean value in the local and overall heat transfer rate is discussed along with the change in the flow .field.

Rijke 관에서 나선형 가열기에 의한 열음향 파워의 생성

권영필,Kwon, Young-Pil 한국음향학회 2010 韓國音響學會誌 Vol.29 No.8

Thermoacoustic power generation by a spiral heater in the Rijke tube was analyzed numerically. In the analysis, variables were normalized by the angular frequency of the sound and the thermal diffusivity of the air. The effect of the heater wire diameter d, the spacing between wires P-d, and the air-current velocity $U_0$, upon the power generation was obtained and discussed. When the spacing is broad enough, the normalized velocity is $U_0{\approx}0.8$ and the diameter is $d{\approx}4$ for the maximum power generation. With decrease of the spacing, however, the power generation increases more than 5 times and becomes maximum around $d{\approx}2$, $P-d{\approx}3$. And the velocity $U_0{\approx}0.8$ for the maximum power generation is almost independent of the wire spacing. Rijke관에 놓인 나선형 가열기에 의하여 생성되는 열음향 파워를 수치해로 구하였다. 음장의 각진동수와 공기의 열확산계수에 의하여 무차원화한 가열선의 지름 d, 간격 P-d 및 유속 $U_0$가 음향 파워 생성에 미치는 영향을 구하고 고찰하였다. 가열선 간격이 충분히 클 때 무차원 유속이 $U_0{\approx}0.8$, 무차원 지름이 d.4일 때 가장 큰 열음향파워가 생성된다. 그러나 가열선 사이의 간격이 가까워지면 음향 파워 생성이 크게 증가하며 $d{\approx}2$, $P-d{\approx}3$에서 최대로 되며, 간격이 충분히 먼 경우의 최대값의 5배 이상이 될 수 있다. 최대 음향파워를 생성하는 유속은 가열선 간격에 관계없이 $U_0{\approx}0.8$일 때이다.

탄화규소 불투명화재와 세라믹섬유가 Fumed 실리카 단열재의 열전도도에 미치는 영향

권영필,권혁천,박성,이재춘,Kwon, Young-Pil,Kwon, Hyuk-Chon,Park, Sung,Lee, Jae-Chun 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.12

The thermal conductivities of nano-sized fumed silica-based insulation media were investigated by varying a mean particle size of the silicon carbide opacifiers and ceramic fiber content. Opacifying effect of ceramic fiber and silicon carbide powders was discussed in terms of their content and the mean particle size of them. As the fiber contents increased from 10 wt% to 30 wt% in a material, its thermal conductivity at temperatures of about $620^{\circ}C$ decreased from 0.171 $Wm^{-1}K^{-1}$ to 0.121 $Wm^{-1}K^{-1}$. Meanwhile, the thermal conductivity at temperatures of about $625^{\circ}C$ decreased from 0.128 $Wm^{-1}K^{-1}$ to 0.092 $Wm^{-l}K^{-1}$ as the mean SiC particle size decreased from $31{\mu}m$ to $10{\mu}m$.

다공 초음속 분류소음에 관한 실험적 연구

권영필,서기원,Kwon, Y.P.,Suh, K.W. 대한설비공학회 1992 설비공학 논문집 Vol.4 No.2

The objective of this paper is to study experimentally on the noise characteristics of supersonic jet from multihole orifice in the range of jet pressure from $at_g$ to $at_g$ in the reverberation room. At first, the single orifice jets are investigated for various hole diameter from 3.8mm to 10mm. Through the noise spectrum, the turbulent mixing noise and the shock associated noise is analyzed. The noise for confined jets into a tube of diameter 30mm or 90mm with length 2m is investigated in comparision with that for the free jets. The sound power level is measured and compared with thoretical models for free jet. At second, multihole orifice jets are investigated to study the effect of multijet on noise reduction. The spectrum and power level of multijets are measured and compared with single jets. The multi-jets in a confined pipe are also investigated. It is found that the noise spectrum is significantly altered by increasing the number of jet with decrease in jet diameter and also by confining the jet into tube.

원형 덕트용 VAV 댐퍼의 성능 비교

권영필(Youngpil Kwon) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.9

The performance of the typical VAV dampers; blade type, venturi type and blade-orifice type, for the circular duct, is obtained by measuring the volume flow rate as a function of the opening degree. The performance features are discussed by comparing the volume flow rate of each damper. It is shown that the blade-orifice type damper, recently developed, is excellent in its linearity of the performance and that it is worse than the blade type but much better than the venturi type in its flow resistance.

원형 CAV 댐퍼의 개발에 관한 연구

권영필(Youngpil Kwon) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.11

A circular CAV damper has been developed, based on the investigation of the pressure loss, and the flow-resisting moment by the damper blade. When a torsional spring is attached to the damper axle, and the setting angle is adjusted to around 82°, the volume rate across the damper is almost independent of the static pressure. Such a CAV characteristic appears at an opening angle between 40° and 60°, where the normalized moment decreases linearly with the angle. In addition, by adjusting the setting angle, the volume rate can be controlled to within 10% error, regardless of the pressure loss.