• Title/Summary/Keyword: Shock pressure

Search Result 1,012, Processing Time 0.024 seconds

A Study on the Characteristics of the Pulse Wave Impinging upon a Flat Plate (평판에 충돌하는 펄스파의 특성에 관한 연구)

  • Kim, H.D.;Lee, D.H.
    • Proceedings of the KSME Conference
    • /
    • 2000.11b
    • /
    • pp.562-567
    • /
    • 2000
  • The Impingement of a weak shock wave discharged from the open end of a shock tube upon a flat plate was investigated using shock tube experiments and numerical simulations. Harten-Yee Total Variation Diminishing method was used to solve axisymmetric, unsteady, compressible flow governing equations. Experiments were carried out to validate the present computations. The effects of the flat plate and baffle plate sizes on the impinging flow field over the flat plate were investigated. Shock Mach number was vaned in the range from 1.05 to 1.20. The distance between the plate and shock tube was changed to investigate the effect on the peak pressure. From both the results of experiments and computations we obtained a good empirical equation to predict the peak pressure on the flat plate.

  • PDF

Study on Analysis of Two-dimensional Compressible Waves by Lattice Boltzmann Method (격자볼츠만법을 이용한 2차원 압축성 충격파의 유동현상에 관한 수치계산)

  • Kang Ho-Keun;Ro Ki-Deok;Son Kang-Pil;Choi Min-Sun;Lee Young-Ho
    • Proceedings of the KSME Conference
    • /
    • 2002.08a
    • /
    • pp.557-560
    • /
    • 2002
  • In this study, simulation of weak shock waves are peformed by a two-dimensional thermal fluid or compressible fluid model of the lattice Boltzmann method. The shock wave represents an abrupt change in fluids properties, in which finite variations in pressure, internal energies, and density occur over the shock thickness. The characteristics of the proposed model with a simple distribution function is verified by calculation of the sound speeds, and the shock tube problem. The reflection of a weak shock wave by wedge propagating in a channel is performed. The results agree well with those by finite difference method or by experiment. In the simulation of unsteady shock wave diffraction around a sharp corner, we show a flow field of vortical structure near the comer.

  • PDF

An Experimental Study on Micro Shock Tube Flow (Micro Shock Tube 유동에 관한 실험적 연구)

  • Park, Jin-Ouk;Kim, Gyu-Wan;Kim, Heuy-Dong
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.16 no.5
    • /
    • pp.74-80
    • /
    • 2012
  • Past few years have seen the growing importance of micro shock tubes in various engineering applications like micro combution, micro propulsion, particle delivery systems. But in order to efficiently apply Micro Shock Tube to such areas require the detailed knowledge of shock characteristics and flow field inside a micro shock tube. Due to many factors such as boundary layer, low Reynolds number and high Knudsen number shock propagation inside micro shock tubes will be quite different from that of the well established macro shock tubes. In the present study, experimental studies were carried out on micro shock tubes of two diameters to investigate flow characteristics and shock propagation. Pressure values were measured at different locations inside the driven section. From the experimental values other parameters like shock velocity, shock strength were found and shock wave diagram was constructed.

Implosion Analysis of Circular Cylinder using Simplified Model (간이물리모델을 이용한 원통형 압력용기의 내파해석)

  • Nho, In Sik;Cho, Sang Rai;Kim, Yong Yook;Han, Soonhung;Cho, Yoon Sik
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.57 no.1
    • /
    • pp.8-14
    • /
    • 2020
  • The implosion phenomena of pressure vessels operating in deep water under extremely high external pressure have been well known. The drastic energy release to ambient field in the form of pressure pulse is accompanied with catastrophic collapse of shell structure. Such a proximity shock wave could be a serious threat to the structural integrity of adjacent submerged body and several suspected accidents have been reported. In this study, basic research for the occurrence and development of shock wave due to implosion was carried out. The mechanism of pressure pulse generation and energy dissipation were investigated, and a simplified kinematic model to approximate the collapse modes of circular tubes which can be generated by external pressure and implosion was examined. Using the simplified kinematic model, the process of energy dissipation was formulated, and the magnitude of released pressure shock wave was estimated quantitatively. To investigate the validity of developed kinematic model and shock wave estimation process, the results from a nonlinear FE analysis code and collapse test carried out using pressure chamber were compared with the results from the developed kinematic model.

Plume Structure Analysis of an Axisymmetric Supersonic Micro-nozzle at the Various Pressure Ratios (압력비가 변할 때 축대칭 초음속 노즐의 플룸 구조 해석)

  • Kwon, Soon-Duk;Kim, Sung-Cho;Kim, Jeong-Soo;Choi, Jong-Wook;Kim, Yong-Sseok
    • Proceedings of the KSME Conference
    • /
    • 2007.05b
    • /
    • pp.2862-2867
    • /
    • 2007
  • The steady non-reacted compressible flow field in a symmetric micro-thruster, which is used for the accurate attitude control of a satellite, is analyzed varying the nozzle pressure ratio (NPR) to investigate the plume characteristics. The nozzle throat diameter is 0.06 inch and the area ratio is 56. The recirculation region is found just behind the normal shock at the several NPRs due to the locally adverse pressure gradient along the nozzle centerline when the environmental pressure is atmospheric. This phenomenon, the cause of flow loss, is similar to the flow behind a blunt body. As NPR increases the location of Mach disk, characteristics of the normal shock, moves downstream and its strength increases. The Mach number distribution appears in a wave-type patter after the normal shock because oblique shocks are reflected on the shock boundaries especially when NPRs are very high.

  • PDF

Numerical Visualization of the Pseudo-Shock Waves using LES (LES를 이용한 Pseudo-Shock Waves의 가시화)

  • Deng, Ruoyu;Jin, Yingzi;Kim, Heuy Dong
    • Journal of the Korean Society of Visualization
    • /
    • v.13 no.3
    • /
    • pp.29-34
    • /
    • 2015
  • The interaction between a normal shock wave and a boundary layer along a wall surface in internal compressible flows causes a very complicated flow. This interaction region containing shock train and mixing region is called as pseudo-shock waves. Pseudo-shock waves in the divergent part of a rectangular nozzle have been investigated by using large-eddy simulation (LES). LES studies have been done for the complex flow phenomena of three-dimensional pseudo-shock waves. The LES results have been validated against experimental wall-pressure measurements. The LES results are in good agreement with experimental results. Pseudo-shock length and corner separation have been studied in three-dimensional LES model. Comparison of centerline pressure measurement and 3D visualization measurement has been discussed for the corner separation position. It has been concluded that the pseudo-shock length should be measured by using 3D visualization measurement.

Experimental Study of the Shock Wave Dynamics in Micro Shock Tube (Micro Shock Tube에서 발생하는 충격파 실험)

  • Park, Jinouk;Kim, Gyuwan;Kim, Heuydong
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.17 no.5
    • /
    • pp.54-59
    • /
    • 2013
  • Micro shock tubes are now-a-days used for a variety engineering applications such as in the field of aerospace, combustion technology and drug delivery systems. But the flow characteristics of micro shock tube will be different from that of well established conventional macro shock tube under the influence of very low Reynolds number and high Knudsen number formed due to smaller diameter. In present study, experimental studies were carried out to a closed end (downstream) Micro Shock Tube with two different diameters were investigated to understand the flow characteristics. Pressure values were measured at different locations inside the driver and driven section. The results obtained show that with the increase in diameter the shock propagation velocity increases as well as the effect of reflected shock wave will be more significant under the same diaphragm rupture pressure.

Innovative Modeling of Explosive Shock Wave Assisted Drug Delivery (고에너지물질에 의한 약물 전달 시스템 연구)

  • Yoh, Jai-Ick;Kim, Ki-Hong;Lee, Kyung-Cheol;Lee, Hyun-Hee;Park, Kyoung-Jin
    • Journal of the Korean Society of Combustion
    • /
    • v.11 no.4
    • /
    • pp.9-13
    • /
    • 2006
  • Recent advances in energetic materials modeling and high-resolution hydrocode simulation enable enhanced computational analysis of bio-medical treatments that utilize high-pressure shock waves. Of particular interest is in designing devices that use such technology in medical treatments. For example, the generated micro shock waves with peak pressure on orders of 10 GPa can be used for treatments such as kidney stone removal, transdermal micro-particle delivery, and cancer cell removal. In this work, we present a new computational methodology for applying the high explosive dynamics to bio-medical treatments by making use of high pressure shock physics and multi-material wave interactions. The preliminary calculations conducted by the in-house code, GIBBS2D, captures various features that are observed from the actual experiments under the similar test conditions. We expect to gain novel insights in applying explosive shock wave physics to the bio-medical science involving drug injection. Our forthcoming papers will illustrate the quantitative comparison of the modeled results against the experimental data.

  • PDF

Innovative Modeling of Explosive Shock Wave Assisted Drug Delivery (고에너지물질에 의한 약물 전달 시스템 연구)

  • Yoh, Jai-Ick;Kim, Ki-Hong;Lee, Kyung-Cheol;Lee, Hyun-Hee;Park, Kyoung-Jin
    • 한국연소학회:학술대회논문집
    • /
    • 2006.04a
    • /
    • pp.213-217
    • /
    • 2006
  • Recent advances in energetic materials modeling and high-resolution hydrocode simulation enable enhanced computational analysis of bio-medical treatments that utilize high-pressure shock waves. Of particular interest is in designing devices that use such technology in medical treatments. For example, the generated micro shock waves with peak pressure on orders of 10 GPa can be used for treatments such as kidney stone removal, trans-dermal micro-particle delivery. and cancer cell removal. In this work, we present a new computational methodology for applying the high explosive dynamics to bio-medical treatments by making use of high pressure shock physics and multi-material wave interactions. The preliminary calculations conducted by the in-house code, GIBBS2D, captures various features that are observed from the actual experiments under the similar test conditions. We expect to gain novel insights in applying explosive shock wave physics to the bio-medical science involving drug injection. Our forthcoming papers will illustrate the quantitative comparison of the modeled results against the experimental data.

  • PDF

Shock Associated Jet Noise Reduction by a Microjet on the Centerline of the Main Jet (노즐 중심에 설치한 마이크로 제트에 의한 충격파 관련소음 저감)

  • 김진화;유정열
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2003.11a
    • /
    • pp.92-97
    • /
    • 2003
  • By using a centerbody injection, an effort to reduce shock assoicated noise is made in an underexpanded sonic nozzle with an exit diameter of 10mm. The centerbody or micro nozzle, aligned with the axis of the main jet has an o.d. of 2mm and i.d. of 1.5mm. When measured at 90$^{\circ}$ relative to the main jet the farfield noise spectra showed that the screech tones and broadband shock associated noise can be significantly reduced simply by varying the length of the centerbody and/or mass fraction of the microjet. The maximum reduction in overall sound pressure level (OASPL) was as much as 9 and 4 ㏈ at fully expanded jet Mach numbers Mi of 1.3 and 1.5, respectively, when the length of the centerbody was varied from 0 to 4 main nozzle diameters without blowing. With the aid of the blowing, the maximum reduction in OASPL increased to 12 and 7 ㏈ at M$\sub$j/=1.3 and 1.5, respectively. The impact pressure field in the main jet plume strongly suggested that the reduced periodic pressure distribution in the shear layers and/or centerline is responsible for the reduced screech and broadband shock associated noise. Therefore, the steady blowing by a micro centerbody is a promising technique for shock noise reduction in a supersonic jet.

  • PDF