Chemical laser propulsion (CLP) is accompanied by the release of chemical energy in the process of laser propulsion, which can improve laser propulsion performance. In this article the propulsion performance of POM propellant under the constraint of a cylindrical tube-type thruster in atmospheric and nitrogen environments, respectively, has been conducted experimentally. The results indicate that the ablation masses of a single pulse under two gas environments are close, but the momentum coupling coefficient Cm and specific impulse Isp in atmospheric environment are higher than that in nitrogen environment, which demonstrates an exothermic reaction occurred between the ablation product and the environment oxygen. To learn the mechanism of CLP the molecular spectra for ablation products of POM propellant in atmospheric and vacuum environments are measured and analyzed, respectively, and it reveals that the final product in a vacuum is CH2O, while the final products are CO2 and H2O in the atmosphere. Then the chemical reaction, composition and chemical energy release have been confirmed in the atmospheric environment. By using Arrhenius finite rate chemical reaction model with the code Fluent the flow field evolution of ablation product was simulated numerically. The results show the intensity of chemical energy release is related to the contact and mixing degree of the ablation product and the oxygen in the atmosphere, mixing more fully, the chemical energy released more intensively.
This paper introduces a new remote wireless stress testing system, wireless sensor network node principle and key
technology are discussed in this system, combining with WSN (wireless sensor networks) technology and GPRS
network data transmission technology, realizing the remote testing of lifting machinery metal structure. to MDEL900B
handling machine for the testing object, on the base of finite element analysis, test the metal structure stress of key parts
on the MDEL900B handling machine in working condition, by comparition between the results of test and finite element
analysis , the reliability of the testing system is shown .
In order to investigate the laser ablation propulsion property of different materials in atmosphere, experiments are
conducted, with a Nd:YAG passive Q-switch solid laser (single pulse energy 66mJ, pulse width 70ns) as energy source,
black rubber, gray PVC, brass and SiC as testing materials. As results, the momentum coupling coefficients of the
measured materials rise first and then fall with the increase of laser power density, which agrees with the observation of
aluminum in vacuum. Among the tested materials gray PVC shows the lowest plasma ignition threshold, which is
0.86x108w/cm2, and highest momentum coupling coefficient, which is 11.83dyne/w.
A new theoretical model for measurement of average distance from radar to the arbitrary distributed rough surface is concerned in this paper. Reviewing the assumption of the Brown's model, the application restrictions of traditional algorithm based on the model is presented. Through constructing simplified model of the scattering surface, combining the radar equation, analyzing the quantitative relation between the amplitude of the waveform and scattering surface, the simplified expression of average distance measurement is obtained. Furthermore, the concept of average distance measurement model is emphasized and the improvement method is suggested.