This paper describes a computational study to determine the aerodynamic coefficients at subsonic and supersonic speeds using an unstructured flow *** paper presents results of investigation of a flow over 155 mm artil...
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ISBN:
(纸本)9781510806528
This paper describes a computational study to determine the aerodynamic coefficients at subsonic and supersonic speeds using an unstructured flow *** paper presents results of investigation of a flow over 155 mm artillery projectile M107 and the performance of the ANSYS FLUENT computational *** flow around projectile was solved as 3-D unsteady compressible flow.
The characteristics of a uniform-shear flow over a circular cylinder are in- vestigated numerically by using the alternative-direction implicit （ADI） algorithm and a fast Fourier transform （FFT） one in the exponen...
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The characteristics of a uniform-shear flow over a circular cylinder are in- vestigated numerically by using the alternative-direction implicit （ADI） algorithm and a fast Fourier transform （FFT） one in the exponential-polar coordinates for Re = 150 and 0 ≤ K ≤ 0.46. The diagram of lift-drag phase, implying the detail information about the fluctuations of drag and lift as well as the flow patterns in the wake and fluctuating pres- sure on the cylinder surface, is used to describe the effects of the shear rate on the flow. Results show that the upper （or lower） closed curve of a phase diagram corresponds to the first （or second） half shedding cycle. The lift-drag phase diagram will move down-left with the increase of shear rate K such that the lift is exerted from the upper side to the lower side, and the drag on the first half shedding cycle is smaller than that on the second half.
Armor-piercing,fin-stabilized discarding sabot(APFSDS)is generally sabot launched with initial velocities of about 4 to 6 *** and flight stability are the topmost priority of the design of such *** aerodynamic interfe...
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Armor-piercing,fin-stabilized discarding sabot(APFSDS)is generally sabot launched with initial velocities of about 4 to 6 *** and flight stability are the topmost priority of the design of such *** aerodynamic interference that results from the sabot asymmetric discard is extremely important for the shooting dispersion and flight stability of the projectile,therefore,the sabot asymmetric dis-
A numerical model of radiation has been adopted for electrothermM-chemical （ETC） launcher, in which Monte Carlo method and statistical physics are employed to simulate the process of a capillary plasma source in an ...
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A numerical model of radiation has been adopted for electrothermM-chemical （ETC） launcher, in which Monte Carlo method and statistical physics are employed to simulate the process of a capillary plasma source in an ETC launcher. The effect on propellant grains with different average absorption coefficients is discussed. The plasma-propellant interaction is also discussed when combined with a thermal model. Results show that the strong instantaneous radiation is responsible for the transmission of energy to the propellant grains leading to ignition. The efficiency of energy absorption in the propellant bed always maintains a high level. Radiant energy caused by plasma is concentrated around the plaslna injector. And the ＂hot zone＂ efficiency is mainly affected by the properties of propellant grains within a small field around the plasma injector.
A500kJ capacitive pulsed power supply (PPS), consisting of one constant current charger and two pulsed power modules (PPM), has been designed and developed. The energy storage density of the whole PPS is about 1MJ/m 3...
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A500kJ capacitive pulsed power supply (PPS), consisting of one constant current charger and two pulsed power modules (PPM), has been designed and developed. The energy storage density of the whole PPS is about 1MJ/m 3 . The output current of the constant current charger in the PPS is over 12A, and this device has floating charge function for capacitors when the PPS is in the process of waiting trigger discharge. The PPS can work independently or as a basic unit in a large pulsed power supply system used for electromagnetic launch (EML). The main components in a PPM are energy storage capacitor (10kV/250kJ), pulse-shaping inductor (50μH), pulse thyristor and crowbar diode. In this paper we describe the structural characteristics of 250kJ PPM and the design features of its main components. The test operation result of 250kJ PPM is also given. Test results show that the PPM's output peak current is nearly 90kA.
Turbulent control and drag reduction in a channel flow via a bidirectional traveling wave induced by spanwise oscillating Lorentz force have been investigated in the *** results based on the direct numerical simulatio...
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Turbulent control and drag reduction in a channel flow via a bidirectional traveling wave induced by spanwise oscillating Lorentz force have been investigated in the *** results based on the direct numerical simulation(DNS)indicate that the bidirectional wavy Lorentz force with appropriate control parameters can result in a regular decline of near-wall streaks and vortex structures with respect to the flow direction,leading to the effective suppression of turbulence generation and significant reduction in skin-friction *** addition,experiments are carried out in a water tunnel via electro-magnetic(EM)actuators designed to produce the bidirectional traveling wave excitation as described in *** a result,the actual substantial drag reduction is realized successfully in these experiments.
The pulsed power supply (PPS) with capacitor energy storage is the integral part of launch system, which is often used as energy storage element for electrothermal-chemical (ETC) launch, electromagnetic launch (EML), ...
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The pulsed power supply (PPS) with capacitor energy storage is the integral part of launch system, which is often used as energy storage element for electrothermal-chemical (ETC) launch, electromagnetic launch (EML), and other new-concept launch technology. In order to make capacitor charged rapidly, a novel capacitor charging power supply (CCPS) has been developed in this paper characterized by compact size, high charging power density and short charging time. Through comparison and analysis, a full-bridge series resonant zero current switching charging circuit, dry-type transformer, active cooling technology, anti-jamming technique, high integration structure design technology have been adopted. By analysis and calculation, the CCPS, which can satisfy quick and step by step charging to capacitor, with the charging current of about 5A, maximum working voltage of 12kV and charging voltage error of below 0.5%, has been designed. Finally, the CCPS has been developed and verified to be stable and reliable in the system by charging a 250kJ PPS module.
A case study of flow over a body of revolution was done in order to understand the variation of flow parameters past the projectile and performance of the computational code. The pre-processor software ANSYS ICEM-CFD ...
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ISBN:
(纸本)9781510806450
A case study of flow over a body of revolution was done in order to understand the variation of flow parameters past the projectile and performance of the computational code. The pre-processor software ANSYS ICEM-CFD and ANSYS FLUENT 14.5 were used to model 155 mm M107 artillery projectile which has been built in INVENTOR software. The flow over projectile was solved as three-dimensional flow in which angle of attack can be considered in the calculations. Aerodynamic forces and moments are computed with the computational fluid dynamic solver. A modified point mass simulation flight dynamics model is applied for the accurate prediction of trajectory of the projectile via atmospheric flight to final impact point in order to improve its precision.
We develop a self-adaptive algebraic tomography algorithm （SAATA） to investigate the simultaneons reconstruction of concentration and temperature distributions in larger temperature range from two views. The simplif...
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We develop a self-adaptive algebraic tomography algorithm （SAATA） to investigate the simultaneons reconstruction of concentration and temperature distributions in larger temperature range from two views. The simplified optical arrangement with fewer projections is realized by extension of spectral information at multiple wavelengths, resulting in great potential in applications of practical combustion diagnosis. Tile results show SAATA can perform much better reconstructions in 300 3000 K temperature range than genetic simulated annealing algorithm and least-square orthogonal-triangular decomposition method with two- wavelength scheme. More phantoms are created to demonstrate the capability of SAATA to capture the peaks and adapt for both flat and sharp temperature distributions. Meanwhile, the advantage of high stability ensures better reconstruction performance at noise levels from 0.1% to 10% in projections.
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