• Title/Summary/Keyword: High enthalpy flow

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Experimental study on flow field behind backward-facing step using detonation-driven shock tunnel

  • Kim, T.H.;Yoshikawa, M.;Narita, M.;Obara, T.;Ohyagi, S.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.85-92
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    • 2004
  • As a research to develop a SCRAM jet engine is actively conducted, a necessity to produce a high-enthalpy flow in a laboratory is increasing. In order to develop the SCRAM-jet engine, stabilized combustion in a supersonic flow-field should be attained, in which a duration time of flow is extremely short. Therefore, a mixing process of breathed air and fuel, which is injected into supersonic flow-fields is one of the most important problem. Since, the flow inside SCRAM jet engine has high-enthalpy, an experimental facility is required to produce such high-enthalpy flow-field. In this study, a detonation-driven shock tunnel was built and was used to produce high-enthalpy flow. Further-more, SCRAM jet engine model equipped backward-facing step was installed at test section and flow-fields were visualized using color-schlieren technique and high speed video camera. The fuel was injected perpendicular to the flow of Mach number three behind backward-facing step. The height of the step, distance of injection and injection pressure were changed to investigate the effects of step on a mixing characteristic between air and fuel. The schlieren photograph and pressure histories show that the fuel was ignited behind the step.

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AN ACCURATE AND EFFICIENT CALCULATION OF HIGH ENTHALPY FLOWS USING A HIGH ORDER NEW LIMITING PROCESS

  • Noh, Sung-Jun;Lee, Kyung-Rock;Park, Jung-Ho;Kim, Kyu-Hong
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.15 no.1
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    • pp.67-82
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    • 2011
  • Calculation of accurate wall heat flux for high enthalpy flows requires a dense grid system, which leads to significantly large computational time. A high-order scheme can improve the efficiency of calculation because wall heat flux can be obtained accurately even with a relatively coarse grid system. However, conventional high order schemes have some drawbacks such as oscillations near a discontinuity and instability in multi-dimensional problem. To resolve these problems, enhanced Multi-dimensional Limiting Process(e-MLP) was applied as a high-order scheme. It could provide robust and accurate solutions with high order accuracy in calculation of high enthalpy flows within a short time. We could confirm the efficiency of the high order e-MLP scheme through grid convergence tests with different grid densities in a hypersonic blunt nose problem.

Experimental Analysis of a Supersonic Plasma Wind Tunnel Using a Segmented Arc Heater with the Power Level of 0.4 MW (0.4 MW 급 분절형 아크 히터를 이용한 초음속 플라즈마 풍동 특성 실험)

  • Kim, Min-Ho;Lee, Mi-Yeon;Kim, Jeong-Soo;Choi, Chea-Hong;Seo, Jun-Ho;Moon, Se-Yeon;Hong, Bong-Guen
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.9
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    • pp.700-707
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    • 2013
  • Experimental analyses on a supersonic plasma wind tunnel of CBNU (Chonbuk National University) were carried out. In these experiments, a segmented arc heater was employed as a plasma source and operated at the gas flow rates of 16.3 g/s and the total currents of 300 A. The input power reached ~350 kW with the torch efficiency of 51.4 %, which is defined as the ratio of total exit enthalpy to the input power. The pressure of plasma gas in the arc heater was measured up to 4 bar while it was down to ~45 mbar in a vacuum chamber through a Laval nozzle. During this conversion process, the generated supersonic plasma was expected to have a total enthalpy of ~11 MJ/kg from the measured input power and torch efficiency. In addition to the measurement of total enthalpy, a cone type probe was inserted into the supersonic plasma flow in order to estimate the angle between shock layer and surface of the probe. From these measurements, the temperature and the Mach number of the supersonic plasma were predicted as ~2,950 K and ~3.7, respectively.

Determination of Enthalpy in the High Temperature Test Facility (고온 시험장치에서의 엔탈피 결정)

  • Na, Jae-Jeong;Lee, Jung-Min;Kang, Kyung-Taik
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.224-227
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    • 2011
  • In order to determine the enthalpy profile in the high temperature transpiration cooling test facility for the air-breating engine compartments, theoretical calculation and measurement for the flow of the test section are performed. The mass averaged enthalpy value determined by the heat balance and sonic throat methods is 10 MJ/kg. The centerline enthalpy value measured using the slug type copper calorimeter is 15 MJ/kg. Typically, the ratio of centerline and mass averaged enthalpy should be varies from 1.4 to 4. This facility has lower bound of enthalpy profile. It will be effective in testing of high temperature transpiration cooling.

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Performance Characteristics of 0.4 MW Class Arc-Heated Plasma Wind Tunnel (0.4 MW 급 아크가열 플라즈마 풍동의 성능특성)

  • Oh, Philyong;Chinnaraj, Rajesh Kumar;Hong, Seong Min;Shin, Eui Sup;Choi, Seong Man
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.5
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    • pp.115-124
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    • 2018
  • Thermal protection materials (TPMs) are very crucial for the survival of any re-entry space vehicles. One of the systems used for rigorous validation of TPMs is an enhanced Huel type segmented arc-heated plasma wind tunnel. A 0.4 MW class arc-heated plasma wind tunnel has been constructed at Chonbuk National University which is capable of producing high enthalpy supersonic flow. In this paper we have studied the characteristics of plasma flow according to power and mass flow parameters.

Numerical Study on the Two-Dimensional Heat Flow in High-Power Density Welding Process (고에너지밀도용접 과정에서의 2차원 열유동에 대한 수치해석적 연구)

  • Park, Kun-Joong;Jang, Kyung-Chun;Kim, Charn-Jung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.9
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    • pp.1166-1174
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    • 2000
  • This work presents a two-dimensional quasi-steady state model to study the fluid flow and heat transfer in high-power density welding process of thin AISI-304 stainless steel plates. The enthalpy method and the finite volume method were used for a numerical analysis of the mushy region phase change as well as the heat flow at the weld pool and the heat-affected zone. The results show that the mushy region distributed around the weld pool becomes wider downstream and the surface heat losses by convection and radiation can be significant factors in welding process especially when a welding speed is relatively low.

Quasi 1D Nonequilibrium Analysis and Validation for Hypersonic Nozzle Design of Shock Tunnel (충격파 풍동의 극초음속 노즐 설계를 위한 Quasi 1D 비평형 해석 및 검증)

  • Kim, Seihwan;Lee, Hyoung Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.8
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    • pp.652-661
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    • 2018
  • It is necessary to resolve the absolute velocity as well as Mach number to reflect the high temperature effect in high speed flow. So this region is classified as high enthalpy flows distinguished from high speed flows. Many facilities, such as arc-jet, shock tunnel, etc. has been used to obtain the high enthalpy flows at the ground level. However, it is difficult to define the exact test condition in this type of facilities, because some chemical reactions and energy transfer take place during the experiments. In the present study, a quasi 1D code considering the thermochemical non-equilibrium effect is developed to effectively estimate the test condition of a shock tunnel. Results show that the code gives reasonable solution compared with the results from the known experiments and 2D axisymmetric simulations.

Analysis of BNNT(Boron Nitride Nano Tube) synthesis by using Ar/N2/H2 60KW RF ICP plasma in the difference of working pressure and H2 flow rate

  • Cho, I Hyun;Yoo, Hee Il;Kim, Ho Seok;Moon, Se Youn;Cho, Hyun Jin;Kim, Myung Jong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.179-179
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    • 2016
  • A radio-frequency (RF) Inductively Coupled Plasma (ICP) torch system was used for boron-nitride nano-tube (BNNT) synthesis. Because of electrodeless plasma generation, no electrode pollution and effective heating transfer during nano-material synthesis can be realized. For stable plasma generation, argon and nitrogen gases were injected with 60 kW grid power in the difference pressure from 200 Torr to 630 Torr. Varying hydrogen gas flow rate from 0 to 20 slpm, the electrical and optical plasma properties were investigated. Through the spectroscopic analysis of atomic argon line, hydrogen line and nitrogen molecular band, we investigated the plasma electron excitation temperature, gas temperature and electron density. Based on the plasma characterization, we performed the synthesis of BNNT by inserting 0.5~1 um hexagonal-boron nitride (h-BN) powder into the plasma. We analysis the structure characterization of BNNT by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), also grasp the ingredient of BNNT by EELS (Electron Energy Loss Spectroscopy) and Raman spectroscopy. We treated bundles of BNNT with the atmospheric pressure plasma, so that we grow the surface morphology in the water attachment of BNNT. We reduce the advancing contact angle to purity bundles of BNNT.

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Supersonic Mach Disk Characteristics in a Plasma Wind Tunnel (플라즈마 풍동의 초음속 마하 디스크 특성)

  • Chinnaraj, Rajesh Kumar;Oh, Philyong;Choi, Seongman
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.1
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    • pp.61-70
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    • 2019
  • A primary investigation on the underexpanded flow generated in a 0.4 MW class high enthalpy supersonic arc-heated plasma wind tunnel is conducted experimentally. The diameter and the position of the Mach disk from the nozzle exit is measured for overall pressure ratios ranging from 200 to 30. The empirical correlations for Mach disk diameter and position are determined which show very good agreement with experimental results.

Internal Flow Aerodynamic Test of a Mach 5 Scramjet Engine (마하 5 스크램젯 엔진의 내부 유동 공력 시험)

  • Yang, In-Young;Lee, Yang-Ji;Kim, Young-Moon;Lee, Kyung-Jae;Kang, Sang-Hoon;Yang, Soo-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.584-587
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    • 2011
  • An internal flow aerodynamic test was performed for a Mach 5 scramjet engine. The test was done without fuel injection, as a preliminary test for the combustion test. Test engine is an engineering model with intake cross-section of $70mm{\times}200mm$ and total length of 1.7m. Test facility is a blowdown-type, high enthalpy, hypersonic facility. 19 pressures were measured through the holes on the model surface along the engine internal flow passage. It was found that the facility start is possible, and also supersonic flow is maintained inside the engine.

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