Simulation Study On Exhaust Ejection Device In Gas Turbine Cabinet

Gas turbines have the advantages of small size,light weight,and high single machine power.However,during operation,gas turbines have the characteristics of high outlet temperature and large flow rate.If corresponding cooling measures are not taken,it will lead to excessive temperature around the gas turbine,which is not conducive to personnel maintenance and equipment normal operation.Based on the above reasons,it is usually an efficient way to install an injector on a gas turbine,which utilizes the high-temperature and high-pressure exhaust gas of the mainstream fluid to induce cold air in the external environment for mixing and cooling.This article is based on the cooling design of a certain marine gas turbine casing,starting from both internal and external aspects.Set up a branch structure internally to improve the fluid environment inside the box,making its heat transfer more fluid flow field;Build an external exhaust ejector device to save energy and reduce noise.And in order to enhance the injection performance of the exhaust ejector,the trailing edge of the nozzle is slotted to generate flow vortices through the pressure difference at the slit,thereby enhancing the injection coefficient of the ejector.This article uses FLUENT for numerical simulation,obtains a large amount of data,and conducts statistical analysis to provide a certain reference basis for future cooling design of gas turbine casing.The main work of this article includes:1.Before conducting simulation on the scheme,the modeling method was validated based on literature,and the results were compared with those in literature and experimental results.A suitable turbulence model was selected,and the conclusion was drawn: Realizable k-corresponds to the corresponding experimental values,and mesh asexuality verification was performed.2.By conducting fluid operation planning on the interior of the gas turbine casing,a branch structure is established,and the approximate parameters of the injector are derived through relevant empirical formulas.Under the condition of determining the nozzle diameter,optimize the nozzle distance,mixing chamber diameter,and mixing chamber length of the exhaust injector to obtain the optimal size in terms of economy and injection efficiency.And obtain relevant laws: the nozzle distance has a significant impact on the expansion degree of the injected fluid when entering the mixing chamber,so the nozzle distance should not be too large or too small;The diameter of the mixing chamber affects the mixing situation of the fluid in the mixing chamber.An excessively large diameter of the mixing chamber leads to excessive expansion in the mixing chamber,while a small diameter of the mixing chamber prevents some fluid from entering the mixing chamber and instead contacts the wall of the receiving chamber,forming vortices,resulting in a decrease in injection efficiency;The length of the mixing chamber is the key to mixing the working fluid with the injection fluid,but excessive mixing chamber length not only does not greatly improve the injection efficiency but also has adverse economic benefits.Therefore,choosing an appropriate size is necessary.3.In order to increase the injection performance of the exhaust ejector,the trailing edge of the exhaust ejector is slit treated,and the optimal number,width,and length of slits are obtained through orthogonal experiments to improve the injection efficiency.As the number of seams increases,the average ejection coefficient first increases and then decreases;As the seam length increases,the injection efficiency first decreases,then increases and then decreases;As the seam width increases,the ejection coefficients first increase and then decrease.