Effects of Rotation on Harmonic Plane Waves Under Two-Temperature Thermoelasticity

The present article is aimed at a detailed analysis of the effects of rotation on the propagation of harmonic plane waves under two-temperature thermoelasticity theory. We consider a homogeneous and isotropic elastic medium that is rotating with uniform angular velocity. After formulating the problem, we obtain the dispersion relations for the longitudinal and transverse plane waves propagating in the medium and the solutions of dispersion relations are obtained analytically for high-frequency as well as for low-frequency values. On the basis of these solutions, the asymptotic expressions of the important characterizations of the wave fields for high and low frequency values are derived. To observe the behavior of the wave characterizations for the intermediate values of frequency and to examine the effects of rotation on them, computational work is carried out and numerical values of different wave fields for various values of frequency and for various angle of rotation are computed. The results are shown graphically. An in-depth analysis of the effects of rotation on plane wave is presented on the basis of our analytical and numerical results and the several significant points are highlighted. A comparative analysis of our results with the corresponding results in absence of rotation of the body is also presented.     

On the Theory of Two-Temperature Thermoelasticity with Two Phase-Lags

The present paper is concerned with the theory of two temperature thermoelasticity with two phase-lags in which the theory of heat conduction in deformable bodies depends on two distinct temperatures – the conductive temperature and the thermodynamic temperature. A generalized heat conduction law with dual-phase-lag effects was proposed by Tzou (1995) for the purpose of considering the delayed response in times due to the microstructural interactions in the heat transport mechanism. Recently, Quintanilla (2008) has proposed to combine this constitutive equation with a two temperature heat conduction theory and has proved that a dual-phase-lag theory with two temperatures is a well-posed problem. In the present work we consider the basic equations concerning this dual-phase lag theory of two temperature thermoelasticity and make an attempt to establish some important theorems in this context. A uniqueness theorem has been established for a homogeneous and isotropic body. An alternative characterization of mixed boundary initial value problem is formulated and a variational principle as well as reciprocal principle have been established.     

Three-Dimensional Fractional Order Generalized Thermoelastic Problem Under the Effect of Rotation in a Half Space

The current article is concerned with three-dimensional problems for a homogeneous, isotropic thermoelastic half-space subjected to a time-dependent heat source on the surface, which is traction-free under the effect of rotation. The governing equations are taken in the context of fractional order generalized thermoelasticity (Green–Lindsay) theory. Normal mode analysis technique and eigenvalue approaches have been used to solve the non-dimensional equations. Numerical results for temperature, thermal stress and displacement distributions are presented graphically and discussed.     

Analysis of Thermoelastic Waves in Functionally Graded Hollow Spheres Based on the Green-Lindsay Theory

In this article, the Green–Lindsay theory of thermoelasticity is employed to study the thermoelastic response of functionally graded hollow spheres. This generalized coupled thermoelasticity theory admits the second sound phenomena and depicts a finite speed for temperature wave propagation. The materials of the hollow sphere are assumed to be graded through its thickness in the radial direction while a symmetric thermal shock load is applied to its boundary. The Galerkin finite element method via the Laplace transformation is used to solve the coupled form of governing equations. A numerical inversion of the Laplace transform is employed to obtain the results in time domain. Using the obtained solution, the temperature, displacement, radial stress, and hoop stress waves propagation are studied. Also the material distribution effects on temperature, displacement and stresses are investigated. Finally, the obtained results for the Green–Lindsay theory are compared with the results of classical thermoelasticity theory.     

Effect of gravity field on piezothermoelastic medium with three theories

The present paper is aimed at studying the effect of gravity on piezothermoelastic medium. An exact solution to the problem is obtained using the normal mode analysis. Numerical results for the field quantities are given in the physical domain and illustrated graphically. Comparisons are also made with the results predicted by different theories (CT, L–S, and G–L) in the absence and presence of gravity.     

Propagation of the photothermal waves in a semiconducting medium under L-S theory

The model of the equations of generalized thermoelasticity based on the Lord–Shulman theory with one relaxation time is used to study the photothermal waves in a semiconducting medium. The exact expressions for the displacement components, temperature, carrier density, and stress components are obtained using normal mode analysis. Numerically simulated results are obtained and presented graphically for silicon to depict the effect of time parameter on the different physical quantities.     

The Effect of Thermal Loading Due to Laser Pulse in Generalized Thermoelastic Medium with Voids in Dual Phase Lag Model

The aim of the present study is concerned with the thermal loading due to laser pulse on thermoelastic medium with voids in the dual phase lag model (DPL). The material is a homogeneous isotropic elastic half-space and heated by a non-Gaussian laser beam with pulse duration of 8 ps. A normal mode method is proposed to analyze the problem and obtain numerical solutions for the displacement components, stresses, temperature distribution and change in the volume fraction field. The results of the physical quantities have been illustrated graphically by comparison between (DPL) and Lord-Schulman (L–S) theory for two values of time and for different values of a phase-lag of heat flux τ _q .     

GL Model on Reflection of P and SV Waves from the Free Surface of Thermoelastic Diffusion Solid Under Influence of the Electromagnetic Field and Initial Stress

This article is devoted to estimating the influence of magnetic field, electric field and initial stress in an elastic solid half-space under thermoelastic diffusion. The governing equations in the xz-plane are solved taking into consideration the Green–Lindsay (GL) model. The Reflection of dilatational (P) wave and Shear Vertical (SV) wave split into four waves: namely, P wave, thermal wave, mass diffusion wave and SV wave. The reflection phenomena of P and SV waves from the free surface of an elastic solid with thermoelastic diffusion under influence of magnetic field, electric field and initial stress is considered. The expressions for the reflection coefficients for the four reflected waves are obtained. These reflection coefficients are found to depend upon the angle of incidence θ of P and SV waves, thermoelastic diffusion, magnetic field, electric field and initial stress and other material parameters. The numerical values for the reflection coefficients are calculated analytically and presented graphically for varying values of these parameters.     

叶型变化对叶片表面压力场的影响

使用NUMECA软件的FINE／Design3D模块对某型跨音速涡轮叶栅改型前后的导叶进行了单列三维流场计算,并分析了原型与改型叶栅沿叶片型面压力的分布以及叶片吸力面上的静压等值线分布。结果表明,叶片的改型改变了叶片表面的压力场,改善了叶栅内气体的流动。     

叶片弯曲对跨音速涡轮叶栅流场的影响

对均匀加载叶型所构成的直叶栅及不同弯角所构成的弯叶栅流场进行了数值模拟。研究了弯叶片作用下型面压力分布、马赫数等值线及叶片表面压力分布的改变,同时考察了叶片弯曲对马蹄涡及通道涡生成位置的影响。叶片正变后有助于减少端壁处的横向压力梯度,削弱端壁二次流动;另外叶片正弯后会使马蹄涡起始分离点位置向流道中间偏移,促使通道涡提早发生。本文所选用的差分格式为具有ＴＶＤ性质的三阶精度的Ｇｏｄｕｎｏｖ格式,湍流模型为修正后的Ｂ－Ｌ代数模型。     

Numerical Study of the Effect of Imaginary Circle Diameter and Initial Flow Field on the Aerodynamic Field in a Tangentially Fired Furnace

INTRoDUCTIoNInthetangeatiallyfiringsystempulverized-coal-and-airjetsareinjectedintothefurnacethIoughslotbtirnersinfourcornersofthefUInace.Theaxesofburnersaretangellttooneorsevera1imaginarycir-clesinproperordertoformastablerotationalfireballwithhightemperatureinoperation.Sotheimag-inarydiameterofiisanimportantgeometricstructureparameterindesigningatangentiallyfiredfurnace,whichistheemphasisofthisstudy.Atpresent,theimaginarycirclediameterrkiisusuallydesignedwithsmallvalueandtheconcentricfir…     

Novel insights on the impact of top water on Steam‐Assisted Gravity Drainage in a point bar reservoir

As efforts are made to efficiently exploit and recover bitumen resources in Canada, increasingly more complex reservoirs in the Athabasca area continue to challenge the application of Steam‐Assisted Gravity Drainage (SAGD) technology. Several studies have been done to investigate the impact of heterogeneities/complexities such as shale barriers, lean zones, and top and bottom water on the performance of the SAGD process. However, the literature is deficient for point bar deposits with top water zones, a common occurrence in oil sands systems. This study, by using thermal reservoir simulation, examines SAGD performance in a point bar deposit reservoir where an overlying top water and an inclined heterolithic strata (IHS) is present. The results show that where the top water is unconfined and steam injection pressure is higher than that of the top water zone, there is a loss of thermal energy, but the top water does not impact steam chamber development. At steam injection pressure lower than that of the top water zone, top water continuously drains into the reservoir and constrains the size of the chamber. However, the IHS zone helps to delay drainage of the top water into the chamber when steam is injected at underbalanced conditions. Finally, under proper steam injection pressure conditions, top water production can be considerably delayed.     

叶片弯曲对扩压叶栅出口流场的影响

通过由常规直叶片、正弯曲叶片、反弯曲叶片组成的三种矩型扩压叶栅在低速风洞上的实验研究,测得了叶栅出口流场、研究了零冲角下常直叶栅、正弯曲叶栅、反弯曲叶栅对出口总压损失分布情况和二次流速度矢量的影响,讲座了叶片弯曲对扩压叶栅出口流场的改善作用。     

催化剂颗粒粒径对烟气轮机流场影响的模拟研究

使用FLUENT 17.2软件对催化剂不同颗粒粒径下烟气轮机流场特性进行了模拟研究,分析了不同颗粒粒径对高温烟气流场、催化剂运动轨迹以及动叶冲蚀的影响。研究工况：颗粒粒径分别为0.5,1.0,1.5和2.0μm,高温烟气的入口温度为670℃,烟气轮机转子转速为6 263 r/min,高温烟气流量为2 067.92 m³/min。研究结果表明：在所研究的颗粒粒径水平下,颗粒粒径的改变不会对高温烟气流场以及颗粒运动轨迹造成明显的影响;动叶叶片被冲蚀的位置以前缘和尾缘为主,前缘被冲蚀的可能性大于尾缘;动叶叶片被冲蚀的可能性随着颗粒粒径的增加而上升。     

喷嘴位置对新型水煤浆气化炉内流场的影响

为了考察气化炉炉侧喷嘴入射角对炉内流场分布、压力分布和颗粒浓度分布的影响，对一种600kg／h的新型水煤浆气化炉炉内三维流场进行了冷态数值模拟。结果表明，喷嘴距气化炉顶部0．9m时，气化炉炉内流场分布最合理，压力分布和颗粒浓度分布最均匀。分析结果为气化炉的设计和运行提供了参考。     

重力对水平两相湍射流中颗粒行为的影响

研究了重力对空间发展的水平两相平面湍射流中颗粒运动的影响。气相场用 Euler方法求解 ,通过大涡模拟直接求解大尺度涡运动的 Navier- Stokes方程 ,小尺度涡采用 Smagorinsky亚格子模式模拟。颗粒相的运动采用L agrangian方法直接求解。射流 Re数为 1130 0。模拟发现 ,对于 St 1及 St～ 0 (1)的颗粒 ,其在平面射流下游的瞬时分布对重力的影响不敏感。随着颗粒 St数的增大 ,重力对平面射流场中颗粒行为的影响逐渐明显 ,但其作用效果还明显地与两相入射流滑移系数的大小有着直接联系。在小两相入流滑移系数情况下 ,对于 St～ 0 (10 )的颗粒 ,在重力作用下的沉降过程还受到了湍流拟序结构的作用 ,而重力作用导致的更大 St数颗粒的沉降 ,将引起固相粒子在射流下游的非对称分布 ,但它既不是均匀各向同性湍流中颗粒的梯度扩散结果 ,也未呈现出受到湍流拟序结构影响的特征     

温度和压力对旋风分离器内气相流场的综合影响

借助Fluent6.1软件,采用改进的RSM模型对不同温度(293~1373 K)和不同压力(0.1~6.5 MPa)下旋风分离器的气相流场进行了数值模拟.结果表明:切向速度随温度的升高而降低,随压力的升高而升高;但当温度超过1000 K、压力超过1.0 MPa以后,切向速度的变化幅度趋于减少.据此,建立了包含温度与压力综合影响在内的切向速度计算公式.温度升高使内旋流中心区域的轴向速度增大,而压力升高则使其减小.     

水电站厂房结构施工期及运行期温度场仿真分析

采用大型有限元计算软件与自主开发温度场仿真程序相结合,对某水电站厂房依照实际浇筑过程进行了温度场仿真分析,解决了仿真计算中混凝土跳仓浇筑的困难,通过与以前方案比较,说明浇筑方案对厂房温度场分布有较大影响,设计时可选择施工方案来降低温度。     

贯流式机组水电站厂房底板施工期温度场仿真分析

对于水电站厂房这样结构复杂的大型水工结构,提出了将国外著名的大型有限元计算软件与自主开发的温度场、温度应力仿真计算程序相结合的方法,解决了在仿真中实现三维空间内混凝土跳仓浇筑的困难,并对某水电站厂房底板进行了仿真计算分析。利用此方法,工程人员可以根据具体的施工方案、浇筑顺序方便地进行温度场、温度应力仿真分析,掌握温度分布情况,及时采取减小温度应力的相应温控措施。