For general power system, the thermal exhaust at the exit of funnel has obvious infrared radiation characteristics. In this paper, funnel exhaust plume about the dynamic system is modeled and analyzed. The 3D flow field of exhaust plumes is calculated based on CFD methods. A calculation method of high temperature exhaust plume's infrared radiation is obtained by spectral band model and calibration with C-G two parameters. And the effect of the detecting azimuth angle on the flow field and the infrared radiation of ship exhaust plumes is analyzed. It can be concluded that with the detection angles’ increasing, the space distribution of the exhaust plume shows a tendency to increase progressively. The difference of the radiation intensity of different detection angles can be up to 32.6%.
The aviation jet engine is the main infrared radiation source of aircraft ,and also the main target for the detection and attack of infrared precision guided weapon systems. The study of spectral radiation characteristics of jet engine exhaust plume is of great significance for the detection, early warning and identification. This paper introduces a test method for the spectral radiance of aero-engine exhaust plume, and analyzes the uncertainty of the measurement results. The test results show that this method can effectively obtain the infrared spectral radiance of the exhaust plume, and the measurement uncertainty is 19.54%. It can effectively obtain the infrared spectrum radiation data of the engine exhaust plume, and provide test parameter support for the infrared spectrum radiation characteristics of the jet engine, the aircraft infrared stealth design, the anti-stealth detection, the infrared stealth technology research and the infrared seeker design.
Cloud is a common natural phenomenon in the sky, and has an irregular and arbitrary appearance. Cloud has serious interference with optical sensors, so it is meaningful to research the optical characteristic of cloud. In this paper, lidar was used to measure the vertical atmosphere, and the atmospheric extinction characteristic data were obtained by retrieving the measured data. During the measurement period, clouds appeared in the sky, and it information was recorded. The extinction characteristics of cloud, the height of cloud bottom and the height of cloud top were given, and the transmittance and optical thickness of the cloud were further analyzed.
Contains H2, CO and unburned components of high-temperature plume of rocket engine, then injected into the atmosphere, continue to carry out the oxidation reaction in the plume near field region with the volume in the plume of oxygen in the air, two times burning. The afterburning is an important cause of infrared radiation intensification of propellant plume, which increases the temperature of the flame and changes the components of the gas, thus enhancing the infrared radiation intensity of the flame. . Two the combustion numerical using chemical reaction mechanism involving HO2 intermediate reaction, the study confirmed that HO2 is a key intermediate, plays a decisive role to trigger early response, on afterburning temperature and flow concentration distribution effect. A finite rate chemical reaction model is used to describe the two burning phenomenon in high temperature plume. In this paper, a numerical simulation of the flame flow field and radiative transfer is carried out for the afterburning phenomenon. The effects of afterburning on the composition, temperature and infrared radiation of the plume are obtained by comparison.
Hypersonic body moving in the atmosphere will suffer high temperature reacting flows which will emit complex radiation. Theoretical calculation was taken in this paper for a hypersonic non-ablative sphere. Hypersonic flow around the sphere was simulated using 9 species chemical kinetic and two temperature thermal non-equilibrium model. Based on this simulated flow field, the LOS method is used to solve radiative transfer and line-by-line model is used to calculate the spectrum from molecular and atoms in mid-infrared. The spectra from different components have been analyzed one by one. The calculation founds out that atom N and O diatomic molecule NO and bremsstrahlung will be important radiation source in this pure air hypersonic flow field. The radiation from hypersonic flow field has been analyzed in both high pressure environment and low pressure environment.
The influences of complex refractive index and particle diameter distribution on the spectral transmittance are studied by MIE scatter theory, the spectrum correlation problem of spectral transmittance in different cases is analyzed, the feasibility that using a single point of spectral transmittance to estimate other points is discussed. The results demonstrate that, Refractive index has a great influence on the spectral selectivity, Absorption index however has little effect on it; the particle diameter distributions have a great influence on spectral transmittance, if only contains a kind of particle, with little difference of particle diameter distribution, can be through a single point of spectral transmittance extrapolation other spectral transmittance, but if the difference is significant, is not feasible