To develop the pressure control algorithm for active braking of adaptive cruise control（ACC） system,a test bench with real parts of the tested vehicle is built.With the dynamic analysis of the active braking actuato...To develop the pressure control algorithm for active braking of adaptive cruise control（ACC） system,a test bench with real parts of the tested vehicle is built.With the dynamic analysis of the active braking actuators,it is demonstrated that different duty of pulse-width modulation（PWM） signals could control the pressure changing rate of the wheel cylinder.To obtain that signal,a modified proportional-integral-differential（PID） control algorithm is developed using the variable parameter method,the control value reset method,the dead zone method and the integral saturation method.Experimental results show that the delay and overshoot of the pressure response could be reduced considerably using the modified PID algorithm compared with the conventional one.The proposed pressure control algorithm could be used for the further development of the ACC＇s controller.展开更多
Active control of turbine blade tip clearance continues to be a concern in design and control of gas turbines. Ever increasing demands for improved efficiency and higher operating temperatures require more stringent t...Active control of turbine blade tip clearance continues to be a concern in design and control of gas turbines. Ever increasing demands for improved efficiency and higher operating temperatures require more stringent tolerances on turbine tip clearance. In this paper, a turbine tip clearance control apparatus and a model of turbine tip clearance are proposed; an implicit active generalized predictive control （GPC）, with auto-regressive （AR） error modification and fuzzy adjustment on control horizon, is presented, as well as a quantitative analysis method of robust per- turbation radius of the system. The active clearance control （ACC） of aero-engine turbine tip clear- ance is evaluated in a lapse-rate take-off transient, along with the comparative and quantitative analysis of the stability and robustness of the active tip clearance control system. The results show that the resultant active tip clearance control system with the improved GPC has favorable steadystate and dynamic performance and benefits of increased efficiency, reduced specific fuel consump- tion, and additional service life.展开更多
Blade tip clearance(BTC) is one of the key factors affecting the efficiency and reliability of high performance turbomachinery such as heavy duty steam turbines, aircraft engines and other gas turbo machines. The self...Blade tip clearance(BTC) is one of the key factors affecting the efficiency and reliability of high performance turbomachinery such as heavy duty steam turbines, aircraft engines and other gas turbo machines. The self-adjusting ability of BTC according to the operation condition changing is important to meet the requirement of performance. In this paper, the principle and method of adjusting the BTC by controlling the axial displacement of the rotor were proposed and studied. The basic principle is that the BTC of the turbomachinery with a conical tail shroud will be affected by the axial displacement of rotor and thereby can be adjusted by controlling the axial position of rotor, which can be adjusted by the controllable oil pressure acting on the thrust bearing. To reach a higher control precision, lower noise and model perturbation, an adaptive quasi-sliding mode control(AQSMC) algorithm based on the disturbance observer(DOB) was designed, and numerical and experimental investigations were carried out. The numerical simulation results show that this algorithm can not only effectively suppress the disturbance, but also, compared with the general reaching law, effectively reduce the chattering and transient high gain switching effect of the closed-loop controller system and avoid the instability caused by the controller. Based on the DOB-AQSMC algorithm, the BTC was stabilized within 2 s with no overshoot and no misalignment in the test rig, and this algorithm achieves a better control performance than the proportion-integral-differential(PID) algorithm. These achievements can be used to push forward the intelligent turbomachinery development.展开更多
This paper presents a numerical investigation of an active tip-clearance control method based on cooling injectionfrom the blade tip surface. It aims to study the influences of air injection on controlling tip clearan...This paper presents a numerical investigation of an active tip-clearance control method based on cooling injectionfrom the blade tip surface. It aims to study the influences of air injection on controlling tip clearance flow, withemphasis on the effects of the injection location on secondary flow and the potential thermal benefits from thecooling jet. The results show that injection location plays an important role in the redistribution of secondary flowwithin the cascade passage. Injection located much closer to the pressure-side comer performs better in reducingtip clearance massflow and its associated losses. However, it also intensifies tip passage vortex, due to less restraintderiving from the reduced tip clearance vortex. Lower plenum total pressure is required to inject equivalentamount of cooling air, but the heat transfer condition on the blade tip surface is a bit worse than that with injectionfrom the reattachment region. Thus the optimum location of air injection should be at the tip separation vortex region.展开更多
In an effort to reduce the blade tip clearance leakage in turbine designs, this article aims to numerically investigate the effects of active jet-flow injected from the blade tip platform upon the blade tip clearance ...In an effort to reduce the blade tip clearance leakage in turbine designs, this article aims to numerically investigate the effects of active jet-flow injected from the blade tip platform upon the blade tip clearance flow. A CFD code integrated with dense-correction-based 3D Reynolds-averaged Navier-Stokes equations together with the well-proven Reynolds stress model (RSM) is adopted. The variation of specific heat is taken into consideration. The effects of jet-flow on the tip clearance flow are simulated ...展开更多
基金Supported by the Ministerial Level Advanced Research Foundation(40401040302)
文摘To develop the pressure control algorithm for active braking of adaptive cruise control（ACC） system,a test bench with real parts of the tested vehicle is built.With the dynamic analysis of the active braking actuators,it is demonstrated that different duty of pulse-width modulation（PWM） signals could control the pressure changing rate of the wheel cylinder.To obtain that signal,a modified proportional-integral-differential（PID） control algorithm is developed using the variable parameter method,the control value reset method,the dead zone method and the integral saturation method.Experimental results show that the delay and overshoot of the pressure response could be reduced considerably using the modified PID algorithm compared with the conventional one.The proposed pressure control algorithm could be used for the further development of the ACC＇s controller.
文摘Active control of turbine blade tip clearance continues to be a concern in design and control of gas turbines. Ever increasing demands for improved efficiency and higher operating temperatures require more stringent tolerances on turbine tip clearance. In this paper, a turbine tip clearance control apparatus and a model of turbine tip clearance are proposed; an implicit active generalized predictive control （GPC）, with auto-regressive （AR） error modification and fuzzy adjustment on control horizon, is presented, as well as a quantitative analysis method of robust per- turbation radius of the system. The active clearance control （ACC） of aero-engine turbine tip clear- ance is evaluated in a lapse-rate take-off transient, along with the comparative and quantitative analysis of the stability and robustness of the active tip clearance control system. The results show that the resultant active tip clearance control system with the improved GPC has favorable steadystate and dynamic performance and benefits of increased efficiency, reduced specific fuel consump- tion, and additional service life.
基金supported by the National Natural Science Foundation of China(Grant Nos.51775030&11802153)the Fundamental Research Funds for the Central Universities(Grant No.BHYC1703A)
文摘Blade tip clearance(BTC) is one of the key factors affecting the efficiency and reliability of high performance turbomachinery such as heavy duty steam turbines, aircraft engines and other gas turbo machines. The self-adjusting ability of BTC according to the operation condition changing is important to meet the requirement of performance. In this paper, the principle and method of adjusting the BTC by controlling the axial displacement of the rotor were proposed and studied. The basic principle is that the BTC of the turbomachinery with a conical tail shroud will be affected by the axial displacement of rotor and thereby can be adjusted by controlling the axial position of rotor, which can be adjusted by the controllable oil pressure acting on the thrust bearing. To reach a higher control precision, lower noise and model perturbation, an adaptive quasi-sliding mode control(AQSMC) algorithm based on the disturbance observer(DOB) was designed, and numerical and experimental investigations were carried out. The numerical simulation results show that this algorithm can not only effectively suppress the disturbance, but also, compared with the general reaching law, effectively reduce the chattering and transient high gain switching effect of the closed-loop controller system and avoid the instability caused by the controller. Based on the DOB-AQSMC algorithm, the BTC was stabilized within 2 s with no overshoot and no misalignment in the test rig, and this algorithm achieves a better control performance than the proportion-integral-differential(PID) algorithm. These achievements can be used to push forward the intelligent turbomachinery development.
文摘This paper presents a numerical investigation of an active tip-clearance control method based on cooling injectionfrom the blade tip surface. It aims to study the influences of air injection on controlling tip clearance flow, withemphasis on the effects of the injection location on secondary flow and the potential thermal benefits from thecooling jet. The results show that injection location plays an important role in the redistribution of secondary flowwithin the cascade passage. Injection located much closer to the pressure-side comer performs better in reducingtip clearance massflow and its associated losses. However, it also intensifies tip passage vortex, due to less restraintderiving from the reduced tip clearance vortex. Lower plenum total pressure is required to inject equivalentamount of cooling air, but the heat transfer condition on the blade tip surface is a bit worse than that with injectionfrom the reattachment region. Thus the optimum location of air injection should be at the tip separation vortex region.
文摘In an effort to reduce the blade tip clearance leakage in turbine designs, this article aims to numerically investigate the effects of active jet-flow injected from the blade tip platform upon the blade tip clearance flow. A CFD code integrated with dense-correction-based 3D Reynolds-averaged Navier-Stokes equations together with the well-proven Reynolds stress model (RSM) is adopted. The variation of specific heat is taken into consideration. The effects of jet-flow on the tip clearance flow are simulated ...
