The Development Of New Effective Systems Applicable To Measure Chemiluminescence In Flame

As the intermediate products of combustion,the radical species in flames have a close relationship with flame temperature,radical concentration and heat release.Monitoring the chemiluminescence of these radical species is very informative for having a better understanding of fuel characteristics and combustion process.Suitable equipment is needed to capture chemiluminescence.Although LIF and PLIF have became available for detecting chemiluminescence,their high price and difficult maintenance make them not popular.Most importantly,LIF and PLIF have poor ability to obtain continuous time-series signals due to the intermittency of pulsed lasers.Thus,developing a new effective measuring system with low price can improve the limitations of the existing systems,and it has vital practical significance.In this paper,a new effective system with high spatial resolution for detecting chemiluminescent intensity has been developed.This system is called fixed-point system in this paper.Cassegrain optical principle was used in this system.And it can realize capturing chemiluminescence of local combustion reactions and obtain continuous signals.Another system to take 2D pictures of radical species in flames was also designed and constructed in this paper,and this system is called ICCD system in the paper.The main work and results are as follows:(1)A high-luminosity-light-collection device was developed through design,calculation and optimization by Zemax.In the whole system,the Cassegrain device was used as the prepositive unit for collecting light.The effective light-collection volume has been proved to be an “ellipsoid” area.The area’s short axis diameter is only 0.382 mm,and its long axis diameter is 1.628 mm.The very small volume makes the whole system owning high-spatial resolution.(2)Fixed-point system’s designing scheme and manufacturing process were completed.In the process of installation and debugging,more details about the system were given,such as equipment type,assembling condition,working principle.(3)The system to take 2D pictures of radical species in flames was also designed and constructed,its main component was ICCD camera.And the details about the designing scheme,the working principle of ICCD and shooting process were given,too.Besides,the primary image processing method based on the software which called Solis was introduced briefly.(4)In order to test and verify the feasibility of the fixed-point system applied in the measurement of flames,the related experiments were conducted.In the experiments,chemiluminescent intensity changed with radius was measured at the height of 2cm away from the combustion nozzle.The full spectrum,OH,and CH were detected respectively.The experimental data obtained by the fixed-point system and ICCD system was compared mutually,and the results showed that the data trend was basically identical.The fixed-point system put forward in this paper belongs non-contact.As it doesn’t disturb flame flow field,there are many advantages when it compared with probe-type equipment.What’s more,the photomultiplier tube used in this system can gain continuous signals in time domain owing to its high frequency response.More Complete experimental data of chemiluminescence can be gained when used the ICCD system simultaneously.