Research On The Characteristic Of Thermally Induced Deformation And Vibration Behaviours Of Naval Gas Turbine Discontinuous Rotor

According to the needs of modern naval defense,in order to deal with the emergency,the power equipment should be able to start up in a short period even with the cost of the structure fatigue life.This requires that the naval gas turbine should have reliable start-up characteristics and fast transition state performance.As a result,the researches on the thermal shock distribution,fast start-up curve optimization and the thermally induced transient vibration of rotor during the fast start-up and transition state of naval gas turbine become the critical contents to improve the maneuverability and the raliability of waiship engines.According to the complex transient temperature distribution and the discontinuous structure of waiship engine rotor,a modeling method for the thermal load of gas turbine was proposed in this paper,the thermal-structure coupling mechanism was investigated,the thermally incuded transient vibraiton of discontinuous rotor with thin wall and variable diameter was analyzed,and the method for rotor thermal analysi s and fast start-up curve optimization design for naval gas turbine was proposed.The main research work includes:According to the transient time varying and space temperature distribution of naval gas turbine,the thermal load distribution model was established based on the thermodynamic cycle analysis,the thermal load distribution function coefficients were obtained with the test data of naval gas turbine.With the micro topography of the interface on naval gas turbine rotor,an equivalent connection layer model with axial and circumferential variable conductivity was proposed,the temperature distribution of at the interface of naval gas turbine discontinuous rotor was analyzed.Results show that the proposed method for thermal load model could predict the temperature boundary of engine under various work state,the equivalent connection layer provides an effective method for the temperature analysis of the discontinuous rotor of naval gas turbine,they lay the foundation of thermal deformation and thermlly induced vibration analysis of naval gas turbine rotor.For the discontinuous structure of naval gas turbine rotor,the thermal-structure coupling model was established,and the themral-structure coupling mechanism of the rotor under thermal shock was investigated.With the three dimensional thermal analysis model,the distribution of temperature difference at t he interface of naval gas turbine rotor was studied.The influence of contact parameters on the connection status of discontinuous rotor under thermal shock was analyzed.The characteristics of thermal deformation and its inifluences were investigated.Res ults show that coupling of discontinuous structure and heat conduction is obvious,it has significant influence on the transient heat conduction and thermal deformation of engine discontinuous rotor.The time of fast start-up has influence on the maximun thermal deformation in the process of rotor start,it could be an effective mothod for the thermal analysis of the discontinuous rotor of naval gas turbine under transient thermal shock.For the transient thermal deformation incuded vibration of the naval gas turbine discontinous rotor,propose to use the element for cone drum rotor model,combine the thermal load distribution and equivalent joint interface stiffness of discontinous structure,and the rotor dynamical anylsis model was established of discontinuous rotor with the thermal deformation characteristics.The characteristic of thermal deformation and the mechanism of thermally induced vibration of naval gas turbine were investigated.With the algorithm of rotor transient dynamics analysis,the transient response during different start-up process of discontinuous rotor under the connection load of discontinous structure,excitation of thermal deformation and unbalance were studied.Results show that the position of discontinuous interface and contact parameters has obvious influence on the vibration of rotor.The decaying of thermal deformation will reduce the transient response o f rotor during start-up process.The vibration amplitute of rotor with the circumferential non-uniformly distributed connection load will rise when across the critical speeds.For the obvious transient thermal stress on rotor under the thermal shock during the fast start-up process of naval gas turbine,with the thermal-mechanical coupling analysis,the multivariable optimization design method for the temperature rising curve during fast start-up was proposed,and the maximum transient thermal stress on rotor was reduced effectively.In order to validate the rotor thermal analysis model and the optimization design method,the test rig for model turbine rotor thermal stress analysis under thermal shock was designed and assembled,the experiment result and theorectical result are consistant,which indicates the effect of optimization.Results show that the proposed optimization design method for the start-up process of naval gas turbine could reduce the maximum thermal stress during start-up process or reduce the start-up time,it provides a useful reference for the formulation of fast start-up process of naval gas turbine.