【作者】 王智伟；

【导师】 刘咸定； 顾瑞英；

【作者基本信息】 西安建筑科技大学 ， 供热、供燃气、通风与空调工程， 2005， 博士

【摘要】 本文着重围绕高原样机研制中关键技术与结构优化问题,深入开展了一系列变地域燃油暖风机热力性能及结构优化的理论与实验研究。获得了如下主要研究成果: 为使高原样机能在高海拔地区正常使用,提出了高原样机研制中关键技术的解决方法;分析归纳了炉膛和尾部换热面的设计原则;确定了燃烧器的选型原则及燃烧器的改进方法;确定了系统阻力的计算方法及风机选择的方法。 针对变地域燃油暖风机缺乏应用基础理论研究的问题,深入开展了其热力性能的理论与实验研究,确立了热力系统设计计算方法,揭示了热力性能变化规律。在详细分析了换热机理的基础上,首次建立了其复杂结构热力系统传热计算数学模型,编制了经实验验证的热力计算软件,为不同容量、不同海拔高度此类暖风机的热力系统设计或较核提供了理论依据和软件支持,同时,软件计算所能提供的详尽信息为此类暖风机结构的优化提供了基础和改进方向。利用热力计算软件多工况计算与分析,获得了大气压力、过剩空气系数、送风量等各因素对机组热效率影响的规律。并综合分析了海拔高度对机组热力性能的影响。 为实现流动减阻、探寻流动与换热的匹配性,详细进行了多通道空气流动数值研究,数值分析了不同海拔高度、送风量、送风口位置各工况对多通道空气流动的速度场、压力场的影响,获得了不同工况下三通道流量分配比、流量分配比与其换热匹配性、送风口合理位置、机组压力损失等方面的结论。计算分析表明,海拔高度或送风量的改变,均对流量分配比基本没有影响,但此流量分配比与其换热能力比不相匹配,因而结构优化时,应设法减小环形通道、外壳空间通道的流量,或增强环形通道、外壳空间通道的换热能力,从而使两者相匹配。送风口合理位置,应是送风口中心在燃烧室纵向中心线下方垂直距离为82.5mm位置处。 针对高海拔地区点火困难、燃烧不稳定的问题,开展了燃烧器配风器结构优化数值研究,数值分析了不同海拔高度、漩流片张角、漩流片位置、喷火筒形状等各工况,对配风器点火电极处的速度、漩流区最大切向速度与中心区最大轴向速度之比、燃烧室中心位置横断面最大回流速度与最大轴向速度之比、进口至出口压力损失等影响规律,获得了配风器的优化结构:漩流片张角应为20°,点火时漩流片的位置应在△z=14.5mm(△z为漩流片距配风器出口处的距离),喷火筒形状应为扩缩型。在此基础上,进一步开展了燃烧室空气与油雾混合数值研究,数值分析了液雾喷射角、喷火筒形状、平原/高原等工况,对燃烧室中油雾粒子分散度及空气分布状况的影响,获得了有利于液雾粒子与空气中氧组分充分混合的油雾喷射角、配风器结构型式等。计算分析表明,合理的油雾喷射角为α=50°,合理的配风器结构亦为扩缩型。更多还原

【Abstract】 On key techniques in the development of plateau-type prototype and some problems of the unit structure, a series of theoretical and experimental studies on thermal and dynamical performances & structure Optimization of oil-fired air heating unit for the different altitude zone use were carefully carried out. The main results of the study are as follows:For applying the prototype to high altitude zones, the solutions to these key techniques are put forward. The design principles of firebox and convection surfaces are analyzed and concluded, the rule and means for a burner selection and its structure optimization are proposed, the method for the system resistance calculation and fan selection is determined.Since there is not sufficient fundamental theory for developing the unit, a thorough theoretical and experimental investigation upon thermal and dynamical performances of the unit was conducted carefully. The method of thermal system design and calculation is developed, and the thermal performance is shown. On the basis of heat transfer analyses, the mathematics model of the thermal system is established, the calculation program and software which was validated with experimental data is made, a set of theoretical basis and software is provided for the design and optimization for the unit of different heating capacity and different altitude zone use. By means of the proposed software, impacts of barometric pressure, surplus air coefficient, and supply air volume on heating efficiency of the unit are achieved. Especially the effect of different altitude on the unit thermal and dynamical performance is well understood.For the decrease of air flow resistance and the matching between air flow and heat exchange, numerical simulation of multi-channels air flow in the unit is carefully done. Numerical analyses on the influences of different altitudes, air supply volumes and air supply opening positions on the velocity field and pressure field of multi-channels air flow, the multi-channels flux ratio, the matching of flow and heat transfer, rational air supply opening position, the unit pressure drop are obtained. The research shows that multi-channels flux ratio is almost not varied with altitude and air supply volume, and does not match corresponding flow and heat transfer, therefore the current construction of multi-channel should be improved by reducing the flow flux area of annulus channel, outer space channel or increasing heat flux of annulus channel, outer space channel. The rationalposition of air supply opening is where the vertical distance from the center point of air supply opening to horizontal center line in firebox is 82.5mm.Upon difficult ignition and unstable combustion in high altitude zone, numerical simulation for the optimization of burner structure is conducted. The impacts of different altitude, angle and position of swirl plate, shape of blast tube has been analyzed on air velocity around an ignition electrode, a ratio of maximum tangential velocity in swirl zone to maximum axial velocity in center zone on outlet of blast tube, a ratio of maximum return velocity to maximum axial velocity in center transect of firebox, a pressure drop from inlet of blast tube to outlet of firebox. The optimization structure of burner were attained with an angle 20° of swirl plate, Az=14.5mm of position of swirl plate, a dilatation to shrinkage-type shape of blast tube. Based on these, numerical simulation of the mixing between air and oil spray in firebox is further conducted. In order to enhance the mixing between oil particle and oxygen species of air in firebox, the effects of different angle of oil spray, shape of blast tube, plain/plateau has been determined on a distribution of oil particles and air distribution, the rational structure of burner with an angle 50° of oil spray, a same shrinkage-type shape of blast tube.With regard to numerical simulation, a calculation mode selection, grid-making technique, two-grade calculation method have been investigated, some successful experiences on numerical simulation hav更多还原