【作者】 王伟才；

【导师】 王银燕；

【作者基本信息】 哈尔滨工程大学 ， 动力机械及工程， 2008， 博士

【摘要】 相继增压技术是改善高增压柴油机低工况性能最有效的方法,可以有效地扩大柴油机低工况运行范围、提高经济性能和减少排放,但它需要采用自动控制技术,如果相继增压的切换点和切换延迟等选择不当,特别是在柴油机瞬态过程中,就容易导致压气机喘振、增压器超速、油耗率增加等问题的出现。本文以某船用带有进排气旁通和高工况放气的相继增压柴油机为研究对象,研究这种相继增压系统性能,以改善增压器与柴油机之间的匹配,并获得增压系统的控制规律。本文主要创新点在于:基于MATLAB/SIMULINK仿真平台,开发了带有进排气旁通和高工况放气的相继增压柴油机工作过程仿真程序。建立了相继增压热动力试验台仿真模型,通过仿真计算得到了切换延迟和进气管容积对增压器切换过程的影响规律。建立了采用PID控制的放气阀的相继增压柴油机的瞬态仿真模型,提出了采用可调节放气阀来控制最高爆发压力,确定了PID控制参数,实现了最高爆发压力的优化控制。提出了一种可调相继复合涡轮增压系统。该增压系统将进排气旁通和可调放气措施与相继增压系统相结合使用,扩大了柴油机的工作区域。研究了进排气旁通对相继增压柴油机性能影响,提出了确定进排气旁通区域的方法。本文在MATLAB/SIMULINK软件平台上,建立了准一维的压气机瞬态模型。其中,该模型考虑到了气体通过压气机的延迟效果,可以预测压气机系统瞬态性能,包括压气机喘振和旋转失速。并通过试验数据检验了模型的正确性,模拟了压气机瞬态失稳过程。为了确定压气机特性的喘振边界,采用流量偏差、流量振幅、相对压力偏差、压力振幅和压力信号的失稳频率等参数来评价压气机喘振。其结果表明:压力信号失稳频率能灵敏和准确地判断压气机喘振,压气机喘振边界的预测结果与试验结果吻合良好;压缩系统的转动惯量和稳压室容积影响喘振特性。为了研究相继增压系统瞬态性能,建立了一个相继增压热动力试验台模型,它主要由两台增压器、燃气阀、空气阀、调节阀和一个单管燃烧室组成,重点研究了从一台增压器工作切换到两台增压器工作的过程,分析了切换延迟和进气管容积对相继增压系统切换过程的影响,其结果表明:过短的切换延迟将导致受控增压器的压气机发生喘振;过长的切换延迟将引起基本增压器的压气机发生喘振;当切换延迟取在中间的一段时间内,可以避免压气机发生喘振。为了避免受控压气机发生倒流,进气管容积既不能太小也不能太大。为了研究进排气旁通与相继增压结合使用,在MATLAB/SIMULINK软件平台上,建立了某船用相继增压柴油机稳态性能工作过程仿真模型。对柴油机喘振限制和进排气旁通进行了仿真研究,并结合试验数据,分析了进排气旁通区域,其结果表明:该柴油机的2TC+CAB与2TC的边界线低于2TC喘振限制曲线;当受控压气机发生喘振后,可能诱导基本压气机也发生喘振。针对该柴油机按螺旋桨特性运行情况,对柴油机分别运行在1TC状态、2TC状态和2TC+CAB状态进行稳态性能仿真,研究了扩大进排气旁通区域对柴油机性能的影响。柴油机折合转速在0.8143～0.8762时,开启旁通阀能增加喘振裕度,防止喘振,降低涡轮前温度,扩大柴油机运行范围。建立了某船用相继增压柴油机瞬态仿真模型。对柴油机从一台增压器工作切换到两台增压器工作的过程进行了研究,其结果表明:在切换过程中,如果旁通阀与燃气阀同时开启,可防止压气机运行点进入喘振区。对柴油机按螺旋桨特性运行时的加速和减速过程进行了研究,其结果表明:加速过程的切换延迟应该选择较短的切换延迟;减速过程中适当降低受控增压器的切换点,可以防止压气机喘振。该研究成果对进一步推广应用相继增压技术具有重要的指导价值和工程实践意义,拥有广泛的应用前景。为了限制缸内最高爆发压力,采用了高工况放气措施。建立了以最高爆发压力为输入,以放气阀开启角度为输出的PID控制模型。对柴油机高工况放气过程进行了研究,确定了放气阀控制策略,整定了控制器PID参数,采用抗积分饱和PI控制算法实现了柴油机放气的控制。更多还原

【Abstract】 The sequential turbocharging technology is the most effective method that improves the performance of diesel engine at low condition. The technology can widen the operation range of engine at low condition, and improve the economy performance of engine, and reduce the exhaust pollutants of engine. But the technology needs autocontrol technology. If the switch delay and switch point of turbocharger of sequentially turbocharged engine is incorrectly controlled, especially with respect to transient process of the engine, it will result in some problem such as compressor surge, turbocharger overspeed and high oil consumption rate. Study object of this dissertation was a sequentially turbocharged diesel engine with intake exhaust bypass and high load condition release air. The dissertation focused on the performance of sequential turbocharging system in order to optimize the match between diesel engine and turbocharger and gain the control law of tubocharged system.The primary originalities in this dissertation include some contents as follows. The simulation software of sequential turbocharging diesel engine with intake exhaust bypass and high load condition release air is developed under MATLAB/SIMULINK simulation platform. A model of sequential turbocharging thermodynamic test rig is established. It is gained that the switch delay and volume of inlet pipe have influence on the switch process of turbocharger. A simulation model of sequential turbocharging diesel engine with PID controlled release valve is established. Means that maximum explosion pressure of cylinder is controlled by the regulative release valve is found. Controls parameter of PID is fixed on. PID controller can realize the optimized control of maximum explosion pressure of cylinder. A regulative sequential compound turbocharger system is designed. It can enlarge the operation range of diesel engine. This paper have studied that intake exhaust bypass had influence on the performance of sequential turbocharging diesel engine. How to confirm the region of intake exhaust bypass is answered. A transient model of compressor is established in SIMULINK language. To predict compressor surge and rotating stall, a time delay is used for taking into account the departure of the compressor characteristics for its steady state. The model validity is verified by experiment data The dissertation simulated transient unsteady process of compressor. The compressor surge is detected by the parameters such as flow rate deviation, flow rate swing, relative pressure deviation, and pressure swing and pressure frequency. The results show that pressure frequency can sensitively and truly detect the compressor surge, that the predicted surge line of compressor are in good agreement with experiment surge line. Surge characteristics are affected by moment of inertia and volume of plenum.A sequential turbocharging thermodynamic test rig model is established in order to investigate the transient performance of the sequential turbocharging system. The test rig is composed of two turbochargers, gas valve, air valve, regulating valve and a combustion chamber. The transient switch process from one turbocharger operation to two turbochargers operation is studied. It is analyzed that the switch delay and volume of inlet pipe have influence on the switch process of sequential turbocharging system. The results show that too short switch delay will induce the controlled turbocharger compressor surge, and that too long switch delay will raise the basal turbocharger compressor surge, and that switch delay in the middle time can avoid the compressor surge. Switch delay in the middle time can avoid the compressor surge. The compressor will not flow backwards if the volume of inlet pipe can not too larger and small.A simulation model was designed for the steady state performance of the turbocharger diesel engine based on MATLAB/SIMULINK in order to study the performance of sequential turbocharging system combining with intake exhaust bypass system. Surge limit and intake exhaust bypass of diesel engine are studied by simulation. The region of intake exhaust bypass is analyzed by experimentation results. The results show that borderline of 2TC+CAB and 2TC of the diesel engine is under the surge limit curve of 2TC. If the controlled compressor occur surge, it will raise the surge of basic compressor. It is simulated the steady performance of the diesel engine that operated 1TC state, 2TC state and 2TC+CAB state under screw propeller characteristic operation. Under screw propeller characteristic operation, it is studied that the widen region of intake exhaust bypass affects the performance of sequential turbocharging diesel engine. When the reduced rotation speed of diesel engine is with the range of 0.8143 and 0.8762, opening of intake exhaust bypass valve can increase surge margin, and avoid compressor surge, and reduce the turbine inlet temperature, and enlarge the operation range of diesel engine.Finally, transient simulative model of sequential turbocharging diesel engine are established. The switch process of diesel engine from one turbocharger operation to two turbochargers operation is studied. The studied results show that it can be avoid that operation point of compressor enter into surge region if bypass valve and gas valve are opened at the same time during the switch process. The speedup and speeddown process of diesel engine under screw propeller characteristic operation is studied. The results show that best switch delay of speedup process should be selected short delay. If the switch point of controlled turbocharger is properly lowered, the compressor surge can be avoided. The results of this research have important guiding value and engineering practice meaning to further popularize and apply sequential turbocharging technology. The results have wide application prospect.Release boost air of the diesel engine is used in order to limit maximum explosion pressure of cylinder. PID controller model is designed. Its input signal is maximum explosion pressure. Its output signal is angle of release valve. The process of release boost air of the diesel engine is studied. Control strategy of release valve is obtained. The PID parameters of controller are turned. Use of antiwindup PI control arithmetic realizes the control of release boost air of diesel engine.更多还原