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Category :
Languages : en
Pages : 11
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The objective of this investigation is to evaluate the transient effects of a reaction control jet on the aerodynamic performance of a generic interceptor missile, Three dimensional computations of the highly turbulent flow field produced by a pulsed, lateral jet control thruster and the interaction of this jet with the supersonic free stream and missile boundary layer were completed for different altitudes and thruster conditions. A generic supersonic missile interceptor configuration consisting of a long, slender body (LID=14.1) containing fixed dorsal and tail fins was used in this study. Parametric computational fluid dynamic (CFD) solutions were obtained at two altitudes of 64.5 kft (19.7 km) and 115 kft (35.1 km). Computation of the flow field behaviors at each altitude were completed for the following assumptions: (1) steady state conditions, lateral control jet turned off, (2) steady-state conditions, lateral control jet turned on, (3) transient jet startup simulation, and (4) transient jet shutdown simulation. A thermally perfect gas (gamma=1.4) was assumed for the Mach number 5 free stream and the Mach number 3 lateral jet. Vehicle forces and moments were obtained for each solution by integrating the surface pressures and viscous shear stresses computed on the missile surfaces. These results are applied to assess the influence of the jet interaction (JI) effects on the transient aerodynamic performance of the missile. The analysis indicates that strong transient influence is predicted in the integrated normal force and pitching moment. These effects may be influenced by the dorsal fin interaction with the jet interaction (JI) region.
Author: James DeSpirito
Publisher:
ISBN: 9781423506669
Category :
Languages : en
Pages : 91
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Viscous computational fluid dynamic simulations were used to predict the aerodynamic coefficients and flowfield around a generic canard-controlled missile configuration in supersonic flow. Computations were performed for Mach 1.5 and 3.0, at six angles of attack between 0 and 10, with 0 and 10 canard deflection, and with planar and grid tail fins, for a total of 48 cases. Validation of the computed results was demonstrated by the very good agreement between the computed aerodynamic coefficients and those obtained from wind tunnel measurements. Visualizations of the flowfield showed that the canard trailing vortices and downwash produced a low-pressure region on the starboard side of the missile that in turn produced an adverse side force. The pressure differential on the leeward fin produced by the interaction with the canard trailing vortices is primarily responsible for the adverse roll effect observed when planar fins are used. Grid tail fins improved the roll effectiveness of the canards at low supersonic speed. No adverse rolling moment was observed with no canard deflection, or at the higher supersonic speed for either tail fin type due to the lower intensity of the canard trailing vortices in these cases. Flow visualizations from the simulations performed in this study help in the understanding of the flow physics and can lead to improved canard and tail fin designs for missiles and rockets.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 91
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Viscous computational fluid dynamic simulations were used to predict the aerodynamic coefficients and flowfield around a generic canard-controlled missile configuration in supersonic flow. Computations were performed for Mach 1.5 and 3.0, at six angles of attack between 0 and 10, with 0 and 10 canard deflection, and with planar and grid tail fins, for a total of 48 cases. Validation of the computed results was demonstrated by the very good agreement between the computed aerodynamic coefficients and those obtained from wind tunnel measurements. Visualizations of the flowfield showed that the canard trailing vortices and downwash produced a low-pressure region on the starboard side of the missile that in turn produced an adverse side force. The pressure differential on the leeward fin produced by the interaction with the canard trailing vortices is primarily responsible for the adverse roll effect observed when planar fins are used. Grid tail fins improved the roll effectiveness of the canards at low supersonic speed. No adverse rolling moment was observed with no canard deflection, or at the higher supersonic speed for either tail fin type due to the lower intensity of the canard trailing vortices in these cases. Flow visualizations from the simulations performed in this study help in the understanding of the flow physics and can lead to improved canard and tail fin designs for missiles and rockets.
Author:
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ISBN:
Category : Guided missiles
Languages : en
Pages : 23
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A detailed numerical investigation of the interaction between a lateral jet and the external flow has been performed for a variety of missile body geometries. These include non-finned axisymmetrical bodies and finned bodies with either strakes or aft-mounted tail fins. The computations were performed at Mach numbers 2, 4.5, and 8. To obtain the numerical results, both Reynolds- averaged Navier-Stokes and Euler techniques were applied. The computational results were compared with results from a previously published wind tunnel study that consisted primarily of global force and moment measurements. The results show significant interactions of the jet-induced flow field with the fin surfaces, which produce additional effects compared with the body alone. In agreement with the wind tunnel study, in some cases the presence of lifting surfaces resulted in force and/or moment amplification of the jet interaction with the missile surfaces. The results indicate deamplification of the jet force at Mach 2 for all three bodies. Amplification of the jet force was also observed for high Mach numbers, particularly for the body with strakes. For the results examined here, there were only minor differences in the global force and moment predictions when viscous or inviscid techniques were used. The dependence of the interaction parameters on angle of attack and jet pressure was well predicted by both methods. The numerical techniques showed good agreement with the experiments at supersonic Mach numbers but only fair agreement for the hypersonic, Mach 8 case.
Author: Yanbao Ma
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 702
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 34
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An investigation on side jets in an M = 5.0 flow was conducted on a flat plate as well as on a generic missile configuration. Surface pressure measurements, oil flow visualisations, force measurements and associated numerical simulations gave insight into the interaction of different jet configurations and their influence on the efficiency of side jet control described by the amplification factor. The analysis of the data especially in the wake of the jet showed that the low pressure region is much less dominant than assumed and that the position of the side jet nozzle is vital also with respect to the exploitation of a desired amplification of the side jet thrust.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 456
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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Computational fluid dynamics (CFD) approaches were used to compute the supersonic flow fields and aerodynamic forces and moments on an elliptic projectile with jet interaction. Steady state numerical results have been obtained for the jet interaction problem at a supersonic Mach number, Mach = 4.0, and several angles of attack from 0 deg to 12 deg via Navier-Stokes computational techniques. The jet modeled in this problem is a supersonic helium jet exhausted into the free stream flow at a high pressure. Computed CFD results show the qualitative features and strong flow interaction between the jet and the free-stream flow. In general, very good agreement of the computed aerodynamic coefficients with the experimental data was achieved for all angles of attack investigated for the "jet-on" conditions. The results show the predictive capabilities of CFD techniques for supersonic flow over elliptic projectiles with jet interaction.
Author: Jubaraj Sahu
Publisher:
ISBN:
Category :
Languages : en
Pages :
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