Study On The Ignition And Combustion Performance Of Thin-wall Slit Micro Combustor

As an important part of distributed energy,the micro combustor has been receiving extensive attention.One of its main characteristics is that the volume is relatively small,the combustion time of liquid fuel is very short,and the incomplete combustion loss is relatively large.Therefore,the core problem of the micro burner is how to improve the performance of the combustion chamber as much as possible under the limited space conditions,including improving the combustion thermal efficiency,improving the stability and concentration of the combustion flame,etc.Or how to design a tiny combustion chamber that is lighter and smaller in size while ensuring performance.In this paper,on the basis of the existing structure of 5k W micro combustion chamber,the combustion performance was improved by changing the structure of some combustion chambers.By means of numerical simulation,the structure of combustion chamber flame tube was improved and the head structure of combustion chamber was designed.On the one hand,the heating and emission performance of the designed combustor were measured by combustion tests.On the other hand,the combustion performance of the designed combustor was compared with that of the original combustion chamber.The winter temperature in most parts of my country is very low,which causes the temperature of the car cab to decrease,which affects the comfort of the driver.At the same time,it also has a greater impact on the ignition of the car.Therefore,parking heaters are installed in many cars.To increase the temperature in the cab.Liu Yanfu,Sun Jingyi and others designed a micro-combustion chamber with oblique cut holes as one of the core components of the parking heater.Due to insufficient air supply in the main combustion area,the oblique hole combustion chamber is prone to carbon deposits during the combustion process.In order to improve the excess air coefficient of the head,the original middle hole and mixing hole of the flame cylinder were cancelled,and the heat transfer of the head was blocked by adding a baffle and a shrinkage mouth after the main combustion hole to ensure the temperature of the main combustion area.Numerical simulation was carried out for three kinds of flame cylinder structures.Based on the results of cold and hot state calculation,the shape of reflux zone,reflux rate,flame combustion position,outlet temperature uniformity and other parameters were taken as indexes to select the reflux cylinder structure.Further simulation results showed that the reflux size d=10mm was the most favorable for the combustion chamber to work.In order to improve the combustion thermal response of the combustion chamber,a double-vane combustion chamber was designed for rapid and stable ignition under ignition condition.Working conditions by using the method of orthogonal design to arrange and test index,obtained the geometric parameters of the double blade hydrocyclone,the length of the cyclone,blade stagger Angle,blade taper,inlet slit width on combustion and combustion flow field,the influence of several parameters and the control in the range of the combustion chamber can be stable combustion.Through numerical simulation,it is found that the reflux rate of the flow field can be adjusted by controlling the flue gas outlet area of the combustor head,and the combustion position of the combustor flame can be further adjusted,which further widens the range of the geometric parameters of the cyclone.Ignition tests were carried out on the original combustion chamber and the designed double-vane combustion chamber.It is found that the designed double-vane combustion chamber has a faster and more stable ignition performance.In the oil-to-air ratio tests under different loads,the outlet temperature of the two-vane combustion chamber is higher,and the combustion efficiency is higher.The NO emission is also slightly lower than the original combustion chamber,but its reliable working range is relatively small.Finally,the flame combustion situation of different combustion chamber structures in the process of high load and stable operation was photographed,and the flame image was extracted by Otsu method,and the obtained flame image was transformed into matrix.Compare the combustion performance of different combustion chambers by comparing the centroid coordinates,flame area,and flame brightness in the flame image.It is found that the designed two-vane combustor is better than the original combustor in flame concentration,stability and fullness.