脉冲爆震涡轮发动机原理性试验研究

为研究脉冲爆震燃烧室与涡轮及压气机三者相互匹配的详细机理,建立了脉冲爆震涡轮发动机原理性试验系统,其主要由脉冲爆震燃烧室、涡轮增压器、润滑系统、发动机测控系统等组成。在该试验系统上开展了脉冲爆震涡轮发动机原理性试验研究。首次实现了由脉冲爆震燃烧室驱动涡轮,涡轮带动压气机,压气机压缩空气供给爆震室的全闭环自吸气工作模式。试验结果表明：脉冲爆震涡轮发动机能在自吸气模式下持久、稳定地工作,爆震室与涡轮及压气机三者匹配良好,验证了用脉冲爆震燃烧室替代传统等压燃烧室的可行性。     

脉冲爆震涡轮发动机共同工作特性

为了研究脉冲爆震涡轮发动机（pulse detonation turbine engine,PDTE）共同工作特性和整机性能,建立了其共同工作分析模型。一方面,利用该模型对PDTE原理样机的性能进行了评估并与试验结果进行对比,计算结果表明,模型计算误差不大于11.2%,随着工作频率的提高,PDTE原理样机推力可进一步提升,但共同工作线朝压气机喘振边界靠近。另一方面,以某涡喷发动机为原型,对利用脉冲爆震燃烧室（pulse detonation combustor,PDC）替换主燃烧室后的整机性能进行了研究。计算结果显示:保持PDTE的迎风面积和涡轮前温度与原涡喷相同,PDTE的最佳压气机增压比从原发动机的5.5减小到2.25,当PDTE工作频率达41.5Hz时,流量与原涡喷相同,此时推力比原涡喷提升20.2%,耗油率降低14.0%。      

脉冲爆震涡轮发动机研究进展

介绍了脉冲爆震涡轮发动机的基本概念、主要结构形式以及基本特点.详细介绍了国内外研究状况及课题组的最新研究进展,对脉冲爆震涡轮发动机需要突破的关键技术、主要研究内容以及发展途径进行了探讨.研究表明:相比于传统的涡轮喷气发动机,脉冲爆震涡轮发动机的耗油率能降低5%~15%;在相同的燃烧室入口条件下,与等压燃烧驱动涡轮相比,用脉冲爆震燃烧驱动涡轮时的涡轮的单位输出功率要高;实现了由脉冲爆震燃烧室驱动涡轮,涡轮带动压气机给脉冲爆震燃烧室供气的自吸气模式,表明用脉冲爆震燃烧室代替传统等压燃烧室是完全可行的.     

混合式脉冲爆震发动机原理性试验系统设计、集成与调试

设计、集成了由涡轮增压器、脉冲爆震燃烧室、燃油供给单元、润滑单元和测控单元构成的混合式脉冲爆震发动机原理性试验系统。初步实验研究表明该系统运行可靠。当脉冲爆震燃烧室与涡轮组合工作时,可在一定频率范围内稳定工作;爆震室头部及管壁沿程压力相对于爆震室独立工作时有所提高;压气机出口空气流量远大于爆震室进口空气流量,证明利用压气机给爆震室供气是可行的。在5Hz爆震频率下,涡轮被爆震产物冲击20min后,叶片没有任何烧蚀和裂纹出现。     

涡轴发动机性能在线监测技术研究及试验验证

研究了基于模型的涡轴发动机性能在线监测技术,开发了涡轴发动机性能在线监测软件,并进行了真实台架试车试验验证.试验结果表明:软件能够自动判断发动机是否已进入准稳态工况,并根据当前的大气条件、燃气涡轮转速、动力涡轮转速,实时计算发动机其它状态量与性能量,如压气机增压比、动力涡轮前温度、轴输出功率、耗油率等.与模型计算结果相比,被试发动机压气机增压比稳态测量值最大偏低2.3%左右,反映了被试发动机与基准发动机之间的性能差异,验证了涡轴发动机地面台架试车性能在线监测技术的有效性.      

级间旋转爆震涡轴发动机热力过程及性能分析

针对一种级间旋转爆震涡轴发动机概念建立了集总参数模型,研究了发动机内部温度、压力、流量分配及涡轮效率等参数随爆震燃烧特性的变化规律.研究结果表明:级间旋转爆震燃烧室的引入可实现对燃气的二次增温增压,能够较为明显地提升涡轴发动机单位功率,但同时也将改变发动机主流与冷却气流的流量分配比例,使得涡轮流量系数和级载荷系数变化、...     

两相脉冲爆震涡轮发动机原理性试验

为验证脉冲爆震涡轮发动机（PDTE）的可行性,建立了PDTE原理性试验系统,主要由脉冲爆震燃烧室、离心压气机和向心涡轮等组成.以汽油为燃料,空气为氧化剂,开展了PDTE原理性试验研究.试验结果表明:爆震燃烧室、压气机与涡轮三者能够协调工作,发动机能够在自吸气模式下长时间稳定连续工作,发动机工作频率最高达18Hz.研究中所采用的气动阀对爆震反传压力波具有很好的衰减作用,低频下衰减效果更为明显,发动机工作在6Hz时压力波峰值可衰减93.8%,在18Hz时衰减幅度降为78.4%.反传压力的降低有利于爆震燃烧室与压气机之间的匹配工作,同时可缩短反传距离,有助于提高发动机工作频率.      

带连续爆震加力燃烧室的涡轮发动机循环及推进性能研究

为进一步提升现有涡轮喷气发动机推进性能,可以采用连续爆震加力燃烧室,针对此,本文首先建立考虑了三种耦合热力过程的连续爆震燃烧室热力过程分析模型,通过与传统涡轮发动机性能分析模型相耦合,分析了带连续爆震加力燃烧的涡轮发动机推进性能及加力燃烧室部件特性。结果表明,由于连续爆震燃烧室具有自增压特性,当将其替代传统加力燃烧室可以显著提升加力时涡轮发动机性能;但另一方面,作为加力燃烧室,由于涡轮后气流温度过高,导致连续爆震加力燃烧室增压比的降低,通过对发动机循环参数的选择可以得到改善;同时,连续爆震加力燃烧室部件特性还受到燃烧室进气损失、反应物填充速度及反应物提前燃烧比例影响。     

脉冲爆震外涵加力分排涡扇发动机性能分析

为了研究外涵带脉冲爆震燃烧室分排涡扇发动机的性能，基于部件法建立了外涵装有脉冲爆震燃烧室（PDC）的分排涡 扇发动机性能模型，分析了PDC工作参数、外涵循环参数和飞行工况对整机性能的影响。结果表明：PDC频率提高，PDC增压比和 加力温度提高，发动机单位推力增大，耗油率升高；PDC当量比增大，PDC增压比和加力温度先提高后降低，发动机单位推力先增 大后减小，耗油率一直升高；脉冲爆震外涵加力由于只利用外涵部分气流组织燃烧，耗油率远低于传统加力的，当PDC频率超过 41 Hz时，脉冲爆震外涵加力发动机的单位推力大于传统加力涡扇发动机的；涵道比增大，参与爆震燃烧气流增多，发动机单位推 力增大，耗油率升高。风扇压比提高，发动机单位推力先增大后减小，耗油率一直降低；在飞行高度一定时，飞行马赫数提高，发动 机单位推力减小，耗油率升高；在飞行马赫数一定时，飞行高度增加，发动机单位推力先增大后略微减小，耗油率先降低后略微升 高；在不同飞行工况下，脉冲爆震外涵加力发动机的耗油率远低于传统加力涡扇发动机的。     

涡轴发动机性能退化数学建模研究

分析了航空发动机各部件性能退化原理;分别建立了压气机、燃烧室、涡轮性能退化的部件模型;根据航空自由涡轮式涡轴发动机的工作和使用特点,建立了性能退化的涡轴发动机数学模型;利用该模型,仿真研究了不同部件性能退化对涡轴发动机性能参数的影响。结果表明,建立的模型正确反映了部件退化对涡轴发动机的影响。     

从科技论文的特点看科技论文的选题

本文论述了科技文的特点及选师原则。在特点方面主要就科技论文的科学性,创造性,理论性进行了阐述,在选题方面科技论文选题的客观需要与主条件进行阐述,旨在揭示科技论文的特点与课题选择之间的关系,从而了解其特点,并据此选题,写出符合要求的科技论文。     

某任务计算机调试设备配套软件的设计与实现

简介了任务计算机调试设备配套软件在任务计算机仿真环境中的重要作用 ,对该软件设计方法和流程进行了详细的说明 ,主要介绍了VC ++6 .0环境下串行通信和显示控制软件的设计技术 ,并讨论了如何提高应用程序性能的途径。     

Analysis of a redshifted plasma flow over a sunspot

The ultraviolet spectrum of a redshifted plasma flow appearing over a sunspot observed during the first flight of the High Resolution Telescope Spectrograph (HRTS I) is analysed, and interpreted as a radiatively cooling plasma. For most of the lines emitted from this plasma, the assumption of ionization equilibrium during the cooling is good. However for He II (and other ions with a single electron outside of closed shells), this is not the case. Integrating differential equations for the various ionization fractions of helium and the temperature allows an approximate determination of the abundance of helium relative to other elements whose lines appear in the spectrum of the plasma flow.     

Effect of a transverse plasma jet on a shock wave induced by a ramp

We conducted experiments in a wind tunnel with Mach number 2 to explore the evolution of a transverse plasma jet and its modification effect on a shock wave induced by a ramp with an angle of 24°. The transverse plasma jet was created by arc discharge in a small cylindrical cavity with a 2 mm diameter orifice. Three group tests with different actuator arrangements in the spanwise or streamwise direction upstream from the ramp were respectively studied to compare their disturbances to the shock wave. As shown by a time-resolved schlieren system, an unsteady motion of the shock wave by actuation was found: the shock wave was significantly modified by the plasma jet with an upstream motion and a reduced angle. Compared to spanwise actuation, a more intensive impact was obtained with two or three streamwise actuators working together. From shock wave structures, the control effect of the plasma jet on the shock motion based on a thermal effect, a potential cause of shock modification, was discussed. Furthermore, we performed a numerical simulation by using the Improved Delayed Detached Eddy Simulation(IDDES) method to simulate the evolution of the transverse plasma jet plume produced by two streamwise actuators. The results show that flow structures are similar to those identified in schlieren images. Two streamwise vortices were recognized, which indicates that the higher jet plume is the result of the overlap of two streamwise jets.     

Impact of a cavitation bubble on a wall

Impulse action of a cavitation bubble on a rigid wall is studied depending on the distance between them. We determine the distances at which the periphery pressure maximums on a wall are preserved as well as the distances at which these maximums exceed the water hammer pressure.     

Flow about a jet source with a deflector

We suggest a method to solve one of the model problems of aerohydrodynamics, namely, a problem of a flow about a point source, from which a fluid with density and total pressure, different from the corresponding values in the incoming flow enters. The calculations are carried out for various values of the determining parameter; and the data are compared with the known results. We revealed the advantages of the suggested method in comparison with the known ones.     

Oscillations of a viscous liquid in a cylindrical container

The natural damped frequencies of a viscous liquid in a circular cylindrical container are obtained for slipping and anchored contact line at the container wall r = a. In addition the response to translational forced excitation has been determined. The results may also be applied to viscous liquid in a micro-gravity environment, as long as the contact angle of the liquid surface to the cylindrical container wall is in the vicinity of π/2, indicating, that the free liquid surface equilibrium position remains a plane surface. It could be found that there exists in contrast to frictionless liquid a small filling range, in which the liquid performs only an aperiodic motion. The adherence condition at the side wall was replaced by the somewhat weaker condition of an anchored contact line.     

Solving a radiation problem with forward speed using a lifting surface method with a Green''s function

The progress of seakeeping computations requires development of computating codes for unsteady flows around a ship or its elements. In this paper, we present a method of calculation concerning waves radiated by an oscillating surface-piercing flat plate with forward speed, with a yaw angle. By use of Green's third identity, the problem is transformed into the resolution of a Fredholm integral equation of the first kind by a panel method using Green's function. The Green's diffraction-radiation function with forward speed is used. Its numerical values are calculated by an adaptative integration procedure to reduce the computation time. The present method permits determination of the pressure jump distribution across the plate, the total forces and moments. The results obtained are compared with other numerical methods in hydrodynamics and in aerodynamics, and with experimental data obtained in a water tank.     

Relativistic Energy-Momentum of a Body with a Finite Volume

The problem of energy-momentum in a body with a finite volume has been causing confusion in the theory of relativity, especially in relativistic thermodynamics. Its correct understanding has been given since the early years of relativity, however, erroneous misunderstandings are still found in papers and textbooks to this date. The present paper introduces a simple paradox to demonstrate the problem, and gives a brief review on a way to handle the energy-momentum correctly.     

The intersection of a Loxodrome with a great circle

The intersections of a loxodrome (rhumb line) and a great circle are of interest for some navigational problems, but a closed-form solution cannot be formulated. An algorithm is given for computing approximations to any desired degree of accuracy using Newton's method. By using the equatorial angle φ as an independent variable all solutions can be found rapidly using the modest computational capabilities of a personal computer