[en] This paper describes the method, the procedure and data results of engine vibration test which is carried out on engines for use on unmanned air vehicles. The paper focuses on the testing of rotating propulsion systems powered by an internal combustion engine which is composed of main rotating components such as the alternator, gearbox, propeller , dampers and couplings. Three measurement methods for measuring torsional and lateral vibrations are presented: a. Gear tooth pulse signal. b. Shaft Strain Gage. c. Laser Displacement Sensors The paper also presents data from tests which were performed using each method and discusses the applications, the advantages and disadvantages of each method

[en] The process of reactive in situ synthesis of dense ceramic matrix composites in Ti-B-C, Ti-B-N, Ti-Si-N systems is modeled. These ceramics are fabricated on the basis of compacted blends of ceramic powders, namely Ti-B₄C and/or Ti-BN. The objectives of the project are to identify and investigate the optimal thermal conditions preferable for production of fully dense ceramic matrix composites. Towards this goal heat transfer and combustion in dense and porous ceramic blends are investigated during monotonous heating at a constant rate. This process is modeled using a heat transfer-combustion model with kinetic parameters determined from the differential thermal analysis of the experimental data. The kinetic burning parameters and the model developed are further used to describe the thermal explosion synthesis in a restrained die under pressure. It is shown that heat removal from the reaction zone affects the combustion process and the final phase composition

[en] The formation time scale of axisymmetric vortex rings is studied numerically for relatively long discharge times. Experimental findings on the existence and universality of a formation time scale, referred to as the formation number, are confirmed. The formation number is indicative of the time a vortex ring acquires its maximal circulation. For vortex rings generated by impulsive motion of a piston, the formation number was found experimentally to be approximately 4. Numerical extension of the experimental study to thick shear layers indicates that the scaled circulation of the pinched-off vortex is relatively insensitive of the details of the formation process, such as the velocity program, velocity profile or vortex generator geometry. In contrast, the formation number does depend on the velocity profile

[en] In order to reduce sulfur oxides discharge, Israel Electric Corporation (IEC) is building a wet Flue Gas Desulfurization (FGD) facility at Rutenberg B power station. The primary objective of IEC is to minimize the occurrence of stack liquid discharge and avoid the discharge of large droplets, in order to prevent acid rain around the stack. Liquid discharge from the stack is the integrated outcome of two-phase processes, which are discussed in this work. In order to estimate droplets discharge the present investigation employs analytical models, empirical tests, and numerical calculations of two-phase phenomena. The two-phase phenomena are coupled and therefore cannot be investigated separately. The present work concerns the application of Computational Fluid Dynamic (CFD) as an engineering complementary tool in the IEC investigation

[en] Many cases of radiation transport in nature and technology can be described as a continuum transport process through an interacting Participating Medium, governed by the Radiative Transfer Equation. Current numerical methods for solving the RTE, in particular Discrete-Ordinates based methods, are in a process of rapid development during recent years. However, they are still lacking in generality and sometimes suffer from performance limitations in three-dimensional problems involving strong coupling between ordinate directions. We present a new numerical solution procedure for the Discrete Ordinates approximation of the RTE, including treatment of anisotropic optical properties and generalized boundary conditions. The numerical schemes used here are well established in CFD, but have not been applied previously to the solution of the RTE. The new scheme is guaranteed to converge, subject to a numerical stability condition. We demonstrate the validity of the developed code on a series of verification cases

[en] Estimation of operating conditions for fossil fuel boiler heat exchangers is often required due to changes in working conditions, design modifications and especially for monitoring performance and failure diagnosis. Regular heat exchangers in fossil fuel boilers are composed of tube banks through which water or steam flow, while hot combustion (flue) gases flow outside the tubes. This work presents a top-down approach to operating conditions estimation based on field measurements. An example for a 350 MW unit superheater is thoroughly discussed. Integral calculations based on measurements for all unit heat exchangers (reheaters, superheaters) were performed first. Based on these calculations a scheme of integral conservation equations (lumped parameter) was then formulated at the single tube level. Steady state temperatures of superheater tube walls were obtained as a main output, and were compared to the maximum allowable operating temperatures of the tubes material. A combined lumped parameter - CFD (Computational Fluid Dynamics, FLUENT code) approach constitutes an efficient tool in certain cases. A brief report of such a case is given for another unit superheater. We conclude that steady state evaluations based on both integral and detailed simulations are a valuable monitoring and diagnosis tool for the power generation industry

[en] Radiographic Fluoroscopy (DRF) and Contact Pressure Display (CPD). The CPD method uses a birefiingent integrated optical sandwich for contact stress analysis, e.g. plantar pressure distribution. The DRF method displays and electronically records skeletal motion using X-ray radiation, providing the exact bone and joint positions during gait. Integrating the two techniques, contribution of each segment to the HFS behavior may be studied by applying image processing and analysis techniques. The combined resulted data may be used not only to detect and diagnose gait pathologies but also as a base for development of advanced numerical models of the foot structure

[en] The detrimental environmental effects of pulverized coal power stations are enforcing the installation of additional emission control equipment. Utilization of this equipment significantly increases the installation and operation costs of the power station, which raises the cost of the electricity generated by this power station. Focusing on the flue gas cleaning equipment can substantially reduce the electricity-generating rate. Improving the equipment design is the only available way to reduce the flue gas cleaning costs, without affecting the power station flexibility and availability. An optimal design is defined as the one achieving the least expensive cleaning system (capital and operating costs) while maintaining the original power station operation flexibility (coal variety and partial load performances). Two main changes in the conventional design need to be carried out in order to reach the above-mentioned optimized design. The first modification is to integrate the ESP and FGD at the design criteria stage while considering the influence of each piece of equipment on the other. The second stage is to set one common best efficiency design point to the ESP and the FGD together. Achieving this one common best efficiency point requires some equipment addition and modifications to the conventional ESP and FGD systems. The technology involved in this modification is available and is well proven in operation. Using this technology with the optimal design concept will lead to a significant reduction of the flue gas cleaning costs and will reduce, by this, the electricity production costs

[en] The present work analyses tile results of tests on 575 MW units with tangential firing furnace arrangement in sub-stoichiometric combustion. Tangential firing provides good conditions for implementing sub-stoichiometric combustion owing to the delivery scheme of pulverized coal and air. The furnace was tested in several different modes of operation (Over Fire Air, Bunkers Out Of Service, Excess air, Tilt etc.) to achieve low cost NOx reduction. Actual performance data are presented based on experiments made on lEC's boiler in M.D. 'B' power station

[en] One of the recently suggested methods to minimize undesired thermal distortion of a structure is based on using a curved bi material beam as o structural element. This element can be designed so that when subject to temperature variations the element chord length remains constant, in a broad range of temperatures. Employing such an element as a structural one raises the question of the optimal design that will exhibit zero thermal expansion and the best structural properties. he optimization problem is presented in two stages. First, the optimal curve shape of the beam is sought; assuming the cross section is constant throughout the element. The solution is found a catenary, which can be approximated as a circular arch for the relevant range of parameters. At the second stage, the optimal form of the cross section and the interface location are investigated numerically, for a circular element. Design recommendations are formulated