• Title/Summary/Keyword: Pressure Resonance

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A Study on the Presure Resonance with Combustion Chamber Geometry for a Spark Ignition Engine (스파크 점화기관의 연소실 형상에 따른 공진현상 해석에 관한 연구)

  • Park, Kyoung-Suk;Jang, Seok-Hyung
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.890-895
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    • 2001
  • Pressure resonance frequency that is caused in the combustion chamber can be interpreted to acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(fine element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The reduce error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To make the experimental results equal we could know that the speed of sound that satisfies Draper's equation was selected 13% higher than all the pent-roof type combustion considered.

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A Study on the Pressure Resonance with Combustion Chamber Geometry for a Spark Ignition Engine (스파크 점화기관의 연소실 형상에 따른 공진현상 해석에 관한 연구)

  • Park, Gyeong-Seok;Jang, Seok-Hyeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.12
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    • pp.1905-1910
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    • 2001
  • Pressure resonance frequency that is caused in the combustion chamber can be interpreted by acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(finite element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To match the experimental results, the speed of sound that satisfies Draper's equation is selected 13% higher than the value for pent-roof type combustion chamber.

Effects of Flow Resonance on Heat Transfer Enhancement and Pressure Drop in a Plate Heat Exchanger (유동공진이 판형 열교환기의 열전달 향상과 압력강하에 미치는 영향)

  • Han Sang Kyu;Kang Byung Ha
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.2
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    • pp.165-172
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    • 2005
  • Heat transfer enhancement of three types of brazed plate heat exchangers has been evaluated experimentally. The effects of flow resonance in a plate heat exchanger on the heat transfer rate and pressure drop have been investigated in a wide range of mass flow rates in detail. The problem is of particular interest in the innovative design of a plate heat exchanger by flow resonance. The results obtained indicate that both heat transfer coefficient and pressure drop are increased as mass flow rate is increased, as expected. It is also found that the heat transfer enhancement is increased with an increase in the plate pitch, while the heat transfer is decreased with a decrease in the chevron angle. Pressure drop also increased with an increase in the plate pitch and with a decrease in the chevron angle. Heat transfer enhancement in the plate heat exchangers is maximized by flow resonance and the resonance frequency of the present plate heat exchangers is found to be in the range of $10~15\;Hz$.

A Telemetry Silicon Pressure Sensor of LC Resonance Type (LC공진을 이용한 원격측정용 압력센서의 제작 및 실험)

  • Kim, Hak-Jin;Kim, Soon-Young;Yang, Sang-Sik
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1872-1874
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    • 2001
  • This paper presents an implantable telemetry LC resonance-type pressure sensor to measure the cerebral ventricle pressure. The sensor consists of an inductor and a capacitor. The LC resonant circuit consists of the sensor and an external antenna coil that are coupled magnetically. The resonance frequency of the circuit decreases as the applied pressure increases the capacitance of the sensor. The sensor is designed in consideration of the biocompatibility and long lifetime for continuous monitoring of the ventricle pressure. The sensor is simple to fabricate and small in comparison with others reported previously. The inductor is fabricated by electroplating and the variable capacitor is constructed with a flexible p+ diaphragm. Also, the deflection of the diaphragm, the variation of the capacitance and the resonance frequency are analyzed and calculated.

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Telemetry Silicon Pressure Sensor Using LC Resonance (LC 공진을 이용한 원격측정용 실리콘 압력센서)

  • Kim, Soon-Young;Pak, Jean-Sung;Yang, Sang-Sik
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.2254-2256
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    • 2000
  • This paper presents an implantable telemetry LC resonance-type pressure sensor for the measurement of the ventricle pressure. This sensor consists of a capacitor and an inductor. This resonant circuit is magnetically coupled with an external antenna coil. The resonance frequency of the circuit decreases as the sensor capacitance is increased by the applied pressure. The inductance and the capacitance are 428nH and 0.98${\mu}F$, respectively. The resonance frequency is 245.7MHz when the differential pressure is zero. The sensitivity of the sensor is 9.477kHz/Pa.

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Research of Synthetic Resonance Characteristics for Electrohydraulic Thrust Vector Control Actuation System (전기-유압식 추력벡터제어 구동장치시스템의 합성공진 특성 연구)

  • Min, Byeong-Joo;Choi, Hyung-Don;Kang, E-Sok
    • Aerospace Engineering and Technology
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    • v.7 no.1
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    • pp.151-160
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    • 2008
  • In this paper, the analysis results of synthetic resonance characteristics are described for the electrohydraulic thrust vector control actuation system. The synthetic resonance is induced by integration of position servo actuation system on the flexible launch vehicle mounting structure. The new resonance mode is synthesized due to composition of hydraulic resonance for electrohydraulic position servo system with inertia load condition and structural resonance for flexible mounting structure. This synthetic resonance can make stability of control system worse by feedback and amplification of control system. The exact nonlinear analysis model of this phenomenon is developed to predict and design a control algorithm for improvement characteristics. The DPF (Dynamic Pressure Feedback) control algorithm has been designed and has excellent resonance suppression capability.

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A Study on Frequency-Modulated Methods for Reducing Acoustic Resonance in HID Lamp (고압방전램프의 음향공명감소를 위한 주파수변조에 관한 연구)

  • Kim, Gi-Jung
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.50 no.12
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    • pp.622-626
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    • 2001
  • HID(high intensity discharge)lamps are high pressure mercury lamp, high pressure sodium lamp and metalhalide lamp. metalhalide lamp among these lamps has considered to be one of the most effective artificial light sources and this lamp has good efficiency, good color rendition and good focusing capability, But the shortcorning of metalhalide lamp is known as acoustic resonance phenomena in the discharge tube when lighted by electronic ballast and then acoustic resonance cause various problems such as the arc instability, light output fluctuations. In this paper, to reduce the acoustic resonence phenomena, the electronic ballast was designed by three methods for high frequency operation wish frequency-modulated sinusodial waves in acoustic resonance frequency band. These frequency-modulated methods are resonance frequency and resonance frequency, resonance frequency and non-resonance frequency non-resonance frequency and non-resonance frequency Experiment results could't show the Presence of acoustic resonance visually and it proved that the resonance-generating conditions can be avoided by continuously changing the two operating frequencies in acoustic resonance band (20.59kHz∼94.2kHz).

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A Study on Measurement and Reduction of Cavity Resonance Based on the Internal Acoustic Modeling of Compressor (공조용 압축기의 Cavity Resonance의 측정 및 저감에 관한 연구)

  • Ahn, B.H.
    • Journal of Power System Engineering
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    • v.3 no.2
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    • pp.26-33
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    • 1999
  • Pressure pulsation Inside the discharge and suction cavity of rotary and scroll compressor are often a major source of objectionable noise and vibration. The key factor of these noise and vibration is due to the cavity resonance. It is not only necessary to understanding the characteristics of pulsation in order to reduce the excitation force of gas to the cavity but also to verifying the phenomena of cavity resonance. For the purpose of these understandings, measurement and simulation of cavity resonance can lead to a better understandings how they occur and be very important to identify the ways to reduce the noise efficiently. In this paper, modeling of the cavity(internal acoustics inside the shell) is discussed and simulated using FEM. Results from the simulation are compared with those measurement in experiments. In describing of cavity mode by experiments, it is very important to specify the exact conditions under which they are measured. Finally, this paper shows the one example of reduced cavity resonance in the compressor.

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A Characteristics of pressure Propagation According to Frequency Changes in a Hydraulic Pipeline (유압관로의 주파수변화 따른 압력전파특성)

  • 유영태;나기대;김지환
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.2
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    • pp.71-79
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    • 2002
  • In this paper, an oil hydraulic pipeline is terminated by both rotary sinusoidal flow generator at upstream oriffice at down stream. The pulsating pressure wave from generated by the rotary sinusoidal flow generator, is measured by using sensor. In the analysis of this paper, a component of the fundamental frequency is obtained by using Laplace transformation.. The experimental and analytical results make clear that (1) viscosity is significant role in hydraulic pipe. (2) When pulsating frequency is matched with the natural frequency, resonance frequency occured periodically. According to the study proposed here, dynamic pressure in a circular oil pipe is expressed in propagation of pressure wave with respect to frequency and Bessel function. The resonance at oil temperature $20^{\circ}$$0^{\circ}C$ in this study. The abrupt change of gain value is due to effect of resonance frequency. The results of experiment are compared with the calculated results, and agreement of both results is fairly good.

Rotordynamic Characteristics of High Pressure Multistage Pump (고압 다단펌프 축계 진동 특성 고찰)

  • Song, Ae Hee;Song, Jin Dae;Lim, Woo Seop;Yang, Bo Suk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2012.10a
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    • pp.592-596
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    • 2012
  • This paper presents numerical analysis result of rotor-bearing system of a multi-stage high pressure pump. Especially resonance possibility, stability and damping factor are estimated for a selected commercial multi-stage high pressure pump. The result shows that it is not easy to avoid resonance of rotor-bearing system against main excitation forces which are residual unbalance force and pressure pulsation. This makes damping effect be more important.

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