Contactless Measurement of Hypervelocity Projectile Wake Velocity Distribution

Abstract

This paper presents a microwave approach to investigate the wake velocity distribution of hypervelocity projectile. The ballistic range measurement is carried out to model the transport of hypervelocity object on the ground. An X-band horn antenna sends a continuous sinusoidal wave with f c = 8.7 GHz to the hypervelocity object and detects the reflected signal. The continuous wavelet transform is utilized to obtain the Doppler frequency shift, and the wake velocity is calculated based on the theory of the Doppler effect. The validity of this experiment is confirmed by comparing the measured projectile velocity with that achieved by a laser-based velocity meter. As a contactless method, this approach does not interfere with the wake flow field. Therefore, the velocity distribution achieved in this paper exhibits better accuracy compared with that obtained from other contact approaches. INDEX TERMS Contactless, hypervelocity projectile, wake, velocity.

Velocity Measurement of a Highspeed Underwater Projectile With Laser Barriers

“…The velocity is very stable. Some errors between the experimental results and the actual velocity are caused by (1) the distance between two laser barriers introducing errors because the barrier distance can be measured with an accuracy of 0.1 mm and (2) the parallelism of the two laser barriers introducing errors. The maximum parallelism error is less than 1 mm.…”

“…The velocity is influenced by the launching conditions, procedures, physical parameters of the projectile, and water ripple conditions. It is one of the most important parameters for evaluating weapons, ammunition and ballistic characteristics [1][2]. With this parameter, the force and torque of the projectile can be described with the change in Mach number as well as some physical phenomena of weapons and ammunition during shooting.…”

Establishment of a Wideband Radar Scattering Center Model of a Plasma Sheath

“…At the same time, according to equation (3,4,5), the plasma frequency, plasma relative permittivity and wave vector can be obtained as follows: Step 3: The centrosymmetric axis of the target is parallel to the Y axis. For the mth scattering center, the angle between the electromagnetic wave and the normal line of the target surface, that is, the incident angle of the electromagnetic wave is:…”

“…In the reentry flight environment, plasma generated by the aerothermal effect forms a sheath, which contains a large number of free electrons and has strong reflection, refraction, absorption, and attenuation effects on electromagnetic waves [1]. On the one hand, the plasma sheath will electromagnetically interfere with the radar signal, which will affect the accuracy and accuracy of radar detection; on the other hand, it will produce two reflection signals [2]- [5] in the radar echo, which will affect target detection and recognition and even cause a tracking loss, as shown in Figure 1. To minimize or remove the adverse effects of the plasma sheath on radar detection, it is highly desirable to explore the mechanism of the effect of the plasma sheath on radar detection and improve the method of processing the target radar signal.…”

Research on Target Deviation Measurement of Projectile Based on Shadow Imaging Method in Laser Screen Velocity Measuring System

“…Accurate measurement of a projectile's velocity is an important part of the performance testing technology of weapons as it has a profound impact on the research, production, application, and development of weapons [1][2][3][4]. Therefore, research on the measuring method of the projectile's velocity and how to improve the measuring accuracy of the projectile's velocity have always been the key contents in the field of the weapon's performance evaluation [5][6][7]. At present, the measuring methods of the projectile's velocity are mainly to use interval velocity measuring devices [8][9][10][11].…”