Improved Design Of The Lubrication System Of A Micro Gas Turbine

A micro-gas turbine is made up of a typical and complex engineering system which includes six parts: compressor,combustion chamber,turbine,nozzles,an operating system and the transmission and lubrication system(oil system).It runs in an extremely complex and aerodynamic process.In each subsystem,the oil system aims to provide proper oil for a micro-gas turbine so that each rotating part can be lubricated and cooled when the turbine works.The paper bases on the failure of micro-gas turbine in production,debugging as well as use in outdoor field---white smoke in the jet nozzle to cast an analysis of reasons and engages in improvement in the design and verification via experiment.After an analysis of the working principle and structural characteristics of a micro-gas turbine oil system,the paper then analyzes reasons of the problem in the oil system of a micro-gas turbine.The white smoke in the jet nozzle attributes to the poor oil return.The reasons are as follows: there is too much oil around the lubrication nozzle due to over-supply of oil so that the total oil amount goes beyond the equilibrium point value;oil pump is weak in the oil return,lower than the equilibrium point;oil has contained too much gas so that the oil return of the oil pump fails to go smoothly or the pump lose control in oil return.Then a failure tree on the reasons of the poor oil return is drawn after the analysis so that 22 basic events can be under investigation.As a result,the main reasons are found out.Too much oil around the nozzle loop as well as large gap between the labyrinth of the guild disk axis and rear seal ring stand the main reasons of the failure.The paper resorts to flowmaster software to establish a simulation model of the oil ventilation system and oil supply system of a micro-gas turbine for the sake of further verification of the correct analysis of the reasons.The model is used for a simulation calculation.At the same time,the test data and simulation data are compared.Both of the results show the two groups of data are nearly consistent.To this end,the reason of failure is further determined.Apart from an analysis of the reasons,some measures for improvement in nozzle loops and coating materials of rear sealing ring have been proposed.For instance,the flow rate of the nozzle loops should be controlled and the coating material of rear sealing rings should be replaced by aluminum silica coating with more close connection.Besides,the performance test of the improved micro-gas turbine oil system is also done and it turns out to be qualified owing to the normal operation.Thus,the improvement in the design of the oil system of a micro-gas turbine meets the design requirements and achieves the desired goal.