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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Propulsion Engineers
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Journal DOI :
The Korean Society of Propulsion Engineers
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Volume & Issues
Volume 1, Issue 2 - Dec 1997
Volume 1, Issue 1 - Jun 1997
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A Study on the Interaction Effect Between Spray Fan Formed by Gas/Liquid Swirl Injector
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 1~7
Experimental study was carried out to investigate the interaction effect between spray fan formed by gas/liquid swirl injector. Test variables were supply pressure and injector distance. Water and air were the simulant for the experiment. For water supply only; Collected water mass was concentrated at the lower part of the two spray fan, but this effect was reduced with increasing supply pressure. Both air and water supply1; Collected water mass was again concentrated at the lower part of the impingement point, but this effect was reduced when air/water supply pressure ratio was increased.
Numerical Simulation of the Experimental Investigation of the Two Dimensional Ram Accelerator Combustion Flow Field
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 8~23
Steady and unsteady numerical simulations are conducted for the comparison with the experiments performed to investigate the ram accelerator flow field by using an expansion tube facility in Stanford University. Wavier-Stokes equations for chemically reacting flows are analyzed by fully implicit and time accurate numerical methods with Jachimowski's detailed chemistry model for hydrogen-air combustion involving 9 species and 19 reaction steps. Although the steady state numerical simulation shows a good agreement with the experimental schlieren and OH PLIF images for the case of
fails in reproducing the combustion region behind the shock intersection point shown in the case of
mixture. Therefore, an unsteady numerical simulation is conducted for this case and the result shows all the detailed flow stabilization process. From the result of unsteady numerical simulation, the experimental result seems to be an instantaneous state during the flow stabilization process. The combustion behind the shock intersection point is the result of a normal detonation formed by the intersection of strong oblique shocks that exist at early stage of the stabilization process. At final stage, the combustion region behind the shock intersection point disappears and the steady state result is retained. The time required for stabilization of the reacting flow in the model ram accelerator is found to be very long in comparison with the experimental test time.
A Dynamic Simulation and LQR Control for Performance Improvement of Small Gas Turbine Engine
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 24~32
A nonlinear dynamic simulation of a small gas turbine engine was performed by using DYNGEN program with various environmental conditions. It was observed that the effect of the bleed air flow rate changed to overall engine performance. The real time linear model which was a function of engine rotor speed was resulted to be close to nonlinear simulation results. For optimal LQR controller, it was considered only fuel flow rate or both fuel flow rate and bleed air rate as inputs. In the comparison of both results, the LQR controller with multi input had better performance than that with single input.
Experimental Studies on Flow Characteristics and Thrust Vectoring of Controlled Axisymmetric Jets
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 33~45
Axisymmetric shear layers around a free jet is forced by co-flowing and counter-flowing secondary jets from/to an annular tube around the jet nozzle. The jet potential core extends far downstream with co-flowing secondary jets due to inhibited vortex developing and pairing. For counter-flowing cases, the axisymmetric shear layer around the jet transits from convective instability to absolute instability for velocity ratios R＝1.3～l.65 for the uniform velocity jets. Consequently, the jet potential core length increases and the turbulence level in the jet core is reduced significantly. The jets are controlled better with extension collars attached to the outer nozzle exit because the annular secondary flow is guided well by the extension collars. For the vectoring of jet, the annular tube around the jet is divided in two parts and the only one part is used for suction. The half suction makes the different shear layer around the jet and vectoring the jet by Coanda effect. The vectoring and turbulent components are varied significantly by the suction ratio. The experiments are carried out to investigate the characteristics of forced free jets using flow visualization, velocity and turbulence measurements.
An Analytical Study on Supersonic Under-Expanded Jet
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 46~54
Based upon the results of numerical calculation, empirical scaling equations were made for supersonic under-expanded jets in both axisymmetric and two dimensional flows. The objective of the present study is to find a straightforward method that can predict the under-expanded supersonic jets issuing from various kinds of nozzles. The present empirical equations were agreed with the calculation results of total variation diminishing difference scheme. The supersonic under-expanded jets operating at a given pressure ratio could be well predicted by the present scaling equations.
Analytical Study on Compressible Plow through Abrupt Enlargement and Contraction
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 55~63
The empirical factor and reaction force based on published data were involved to investigate compressible flows through sudden enlargement and sudden contraction passages. Analytical solutions of engineering interest were obtained from one-dimensional steady compressible gas dynamic equations. The effects of com- pressibility, cross-sectional area ratio, and inlet Mach number on the air flows were discussed with regards to the total pressure loss and flow choking. The present results provide available information necessary to design the compressible pipe flow systems.
Unsteady Ignition in the Pulse Combustor with Counter Jet Flows
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 64~72
An analytical study has been performed to investigate the unsteady ignition characteristics of pulse combustion. In many combustion applications, strain rate of the flow can significantly affect the combustion features; ignition, extinction, and reignition. In the pulse combustion, two jets (hot combustion gases and fresh mixtures) coming from the opposite side of the combustor will collide in the combustor forming a stagnation region where the chemical reaction is suppressed by the strain rate until this becomes below the critical value. In this research, the method of large activation energy asymptotic is adopted with one step irreversible kinetics to examine the ignition response to the periodic variation of the strain rate of flow. The results show the variation of the maximum value of strain rate can determine whether the ignition or extinction occur.
Numerical Study on Turbulent Flow and Heat Transfer in the Rocket Nozzle
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 73~81
Numerical analysis on turbulent flow and heat transfer in the rocket nozzle has been studied using the mass-weighted-averaged full Navier-Stokes equations, the Morkovin hypothesis on turbulent flow, the
turbulence model with the wall function specially designed to be able to consider the effects of pressure gradients, heat transfer and compressibility, and the numerical scheme of Karki. The present results are in good agreement with the experiments of Back et al.
Microcracking of Motor Case with Fiberite 934/T300 Laminates under fatigue Loads
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 82~88
The goal is to assess the effect of fatigue loading on mechanical properties of Fiberite 934/T300 laminates of pressure vessel using the recent variational mechanics analysis. This analysis has been useful in providing fracture mechanics interpretation of matrix microcracking in cross-ply laminates. This paper describes using the new energy release rate analysis for a fracture mechanics based interpretation of microcrack formation during fatigue loading. The master plot by modified Paris-law gives a complete characterization of a material system's resistance to microcrack formation.
The Plastic Deformation of Combustion Chamber During the Flow Forming Process with Initial Preform Thickness
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 89~103
The flow forming process which is one of the technologies to manufacture the various missile propulsion combustion chambers, was analyzed using the rigid plasticity finite element modeling. The numerical analysis was performed using 3 rollers which forms the basic tools for the plastic deformation of the tubes. As a result of this study, the distribution of the plastic strain and the stress are obtained and compared. It was found that there exists a significant difference in the plastic deformation as well as the stress distribution due to the preform initial thickness as a result of these numerical experiments. Moreover, under ideal process condition, flow forming process results in a uniform plastic deformation in the radial direction.
Analysis and Measurement of Residual Stress of Al 7175 Ring Rolls after Quenching and stress Relieving
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 104~110
To predict the effect of ring expansion and ring compression on residual stress relief of Al 7175 ring rot]s, 2-D axisymmetric thermal analysis and elastoplastic analysis were performed. The residual stress distributions along the thickness of T73, T7351 and T7352 treated rings were measured using three step sectioning method. The measured results were compared to numerical ones for quenched and stress relieved rings. After quenching, calculated hoop and axial residual stresses were similar to measured ones for T73 treated rings. The residual stresses of T7351 and T7352 treated rings were decreased remarkably compared to T73 treated rings. The effect of axial residual stress relief was superior to that of hoop one, and also ring compression to ring expansion. It was concluded that ring compression is advantageous over ring expansion in view of stress relief effect and practicality, and vice versa in view of dimensional control and press power.
Strength and Failure Mode Prediction of Mechanically Fastened Carbon/Epoxy Joints
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 111~121
An investigation was performed to study the predicting the joint strength of mechanical fasteners. Bearing failure is most important failure mode for designing joint. So in this study, the prediction method in consideration with bearing failure was chosen. In the proposed method, the characteristic length is combined with the Yamada-Sun failure criterion, Tsai-Hill failure criterion and characteristic length for Tension and Compression is determined from investigation. Especially the length of compression is determined from the "bearing failure test" that newly conceived to take bearing failure into consideration. The proposed prediction method was applied to quasi-isotropic carbon/epoxy joint showing net-tension and bearing failure experimentally. Good agreement was found between the predicted and experimental result for each joint geometry. geometry.
Journal of the Korean Society of Propulsion Engineers, volume 1, issue 1, 1997, Pages 122~128