A Fault Diagnosis System for Arc Heater Water Leakage Based on Atomic Emission Spectroscopy

Abstract

The invention discloses an arc heater water leakage fault diagnosis system based on atomic emission spectroscopy. The air is heated by an arc heater and expanded and accelerated by an effuser to formhigh temperature air flow. The flow field spectrum formed by the arc heater is focused by a spectrometric compression film. The focused flow field spectrum is transmitted to a spectral measurement module through an optical fiber. The spectral intensity of the oxygen atomic characteristic spectrum and the spectral intensity of the background spectrum are measured by using the spectral measurement module and then the relative intensity is calculated. The relative intensity is compared with the intensity threshold by a data processing terminal, and the water leakage fault of the arc heater is judged according to the comparison result. When the judgment result indicates water leakage, power supply to the arc heater is disconnected. Rapid diagnosis of the low enthalpy arc heater water leakage fault can be realized so that safe operation of the heater can be guaranteed; and the operation state of the heater can also be monitored in real time so as to provide reference to analysis of the long-term operation stability.

Description

technical field [0001] The invention relates to heater fault diagnosis technology, in particular to an arc heater water leakage fault diagnosis system based on atomic emission spectrum. Background technique [0002] The arc heater is an important test platform to study the aerodynamic thermal protection of aircraft, and its working state and air quality directly determine the reliability of the test. Because the arc heater generates an arc and heats the test gas through the high voltage applied to both ends of the electrode, the high temperature environment brought by the high voltage always causes a certain ablation on the outer surface of the electrode. In order to meet the long-term aerothermal test requirements of hundreds of seconds or even thousands of seconds, high-pressure water is generally used to forcibly cool the electrodes to overcome the problem of electrode ablation. Risk of severe burnout from leaky water heaters. If the ablation amount of the electrode is ...

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Problems solved by technology

In 2005, R.K.Hanson of Stanford University used laser absorption spectroscopy to diagnose the concentration of copper particles in the high-temperature flow field of the 60MW high-enthalpy stacked arc heater (IHF) of NASA AMES Research Center. The research results showed that the laser absorption Spectroscopy technology can realize the online diagnosis of copper particles in the high temperature flow field of the arc heater, and the measurement sensitivity is on the order of 1ppm. Provide reference for the maintenance of the heater, and cannot be directly used to determine the water leakage fault of the arc heater

In 2016, Lin Xin et al. of China Aerospace Aerodynamics Technology Research Institute proposed a water leakage fault diagnosis method for medium and high enthalpy arc heaters (enthalpy value higher than 12MJ / kg, total temperature higher than 5000K) based on H atom radiation. Determine whether there is a water leakage fault by capturing the characteristic spectrum of H atoms at 656.28nm in the flow field, and based on the assumption of thermodynamic equilibrium, combined with the test state (total enthalpy, air intake, etc.), the quantitative measurement of the water leakage at the initial moment of water leakage is realized. , but this method is helpless for low-medium enthalpy arc heaters with enthalpy in the range of 2-12MJ / kg. The H atoms generated by decomposition have sufficient radiation intensity. For low-medium enthalpy arc heaters with an enthalpy range of 2-12MJ / kg, the incomplete decomposition of water and the relatively low airflow temperature in the heater lead to H The radiation intensity of the characteristic spectral line at 656.28nm of the atom is weak, and it is basically completely annihilated in the solid radiation on the inner wall of the heater and the radiation of high-temperature gas, thus greatly reducing the sensitivity of this method applied to low and medium enthalpy arc heaters

Depend on figure 2 It is known that compared with the 777.19nm characteristic line of O atom, the spectral intensity of 656.28nm characteristic line of H atom is extremely weak, especially in the low enthalpy working range. Accurately determine water leakage faults

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