구조연성해석을 통한 메인스타팅 에어밸브의 경량화설계

In this paper, the cooling system of a 200MW air-cooled turbo-generator used in IGCC power station is studied by using multi-physic field analysis under normal operation and insulation aging cases, which will provide theoretical basis for the safety operation of turbo-generator in IGCC power station. Firstly, according to the fluid flow and heat transfer characteristics of multi-path ventilation system in large air-cooled turbo-generator, the 3-D turbulent flow and heat transfer mathematical and physical model of stator with multi-path ventilation system for fluid and temperature coupling analysis is established, which is calculated numerically by using finite volume method (FVM). Secondly, the influence of rotor spinning on stator heat transfer was considered, the turbulent flow in radial ventilation duct was studied and the air-gap flow rule was analyzed. Besides that, the velocity distribution in different ventilation duct was got. Third, the winding temperature and fluid temperature of generator under insulation aging were analyzed, which will provide theoretical basis for the practical engineering. Finally, the stator ventilation cooling system was optimized, and the influence of the width changes of ventilation duct on stator temperature was researched.

In turbulence research, the velocity-pressure-gradient tensor in the Reynolds stress transport equation is critical for understanding and modeling of turbulence. Pressure is also of fundamental importance in understanding and modeling of cavitation. Motivated by the lack of experimental tools to measure the instantaneous pressure distribution away from boundaries, the paper introduces a non-intrusive method for simultaneously measuring the instantaneous velocity and pressure distribution over a sample area. The technique utilizes four exposure PIV to measure the distribution of material acceleration, and integrating it to obtain the pressure distribution. If necessary, e.g., for cavitation research, a reference pressure at a single point is also required. Two cameras and perpendicularly polarized Nd:Yag lasers are used for recording four exposures on separate frames. Images 1 and 3 are used for measuring the first velocity distribution, whereas images 2 and 4 give the second velocity map. The material acceleration is calculated from the velocity difference in sample areas shifted relative to each other according to the local velocity. Averaged omni-directional integration of the material acceleration over the entire flow field, while avoiding regions dominated by viscous diffusion, provides the pressure distribution. To improve the accuracy of the acceleration measurement, cross-correlation of the corresponding image correlation maps is implemented in areas with high velocity gradient. Applications of these procedures to synthetic flows show that the standard deviation of the measured instantaneous pressure from the theoretical value is about 2%. The system has been used to measure the instantaneous pressure and velocity distributions of a 2D cavity flow field in a water tunnel. Three pressure transducers mounted at different locations on the wall are being used for comparison and calibration. Detailed measurements of acceleration, vorticity and pressure distributions within the cavity shear layer indicate that the cavity shear layer flow exhibits highly unsteady behavior due to the self-excited oscillation.

The effects of nozzle contraction ratio on the flow and heat transfer characteristics of orifice impinging jet are investigated experimentally. The nozzle diameter is do=10.0mm=const., and the contraction ratio CR= (do/di) 2, where di is pipe diameter, and the nozzle-plate distance are changed CR=1.00 to 0.11 and H/do=2.0 to 5.0, respectively. The Reynolds number based on do is Re=15000 =const. The flow characteristics are made clear by measurements of pressure and velocity distributions on the plate and flow visualization. The Nusselt number obtained by the measurements of temperature distribution on the plate for the orifice impinging jet of CR=0.11 and 0.69 were 19% and 9% higher than those of the pipe impinging (CR=1.00), respectively, because the centerline velocity of the orifice jet is larger than that of the pipe jet. Under the same operation power an orifice impinging jet has an enhanced heat transfer characteristics.

The effects of the nozzle contraction ratio on the flow and heat transfer characteristics of an orifice impinging jet were investigated in this experiment. The nozzle diameter was do=10.0 mm=const., and the contraction area ratio CR=(do/di)2, where di is the inner pipe diameter was varied from CR=1.00 to 0.11 and the nozzle‐plate distance was varied from H/do=2.0 to 5.0. The nozzle Reynolds number was Re=1.5×104=const. The flow characteristics were clarified by measuring the pressure and velocity distributions on the plate and flow visualization. The Nusselt number obtained from measuring the temperature distribution on the plate of an orifice impinging jet with a CR of 0.11 and 0.69 were respectively larger by 19% and 9% than those of a pipe impinging jet (CR=1.00), because the centerline velocity of the orifice jet was larger than that of the pipe jet. Under the same operation power, an orifice impinging jet has improved heat transfer characteristics. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20225

Performance of flange is characterized by its strength. A number of analytical and experimental studies have been conducted to study this characteristic of flange in pipeline under internal pressure loading. Very few researchers have studied the companion flange which is used in assembly of Universal Drive shaft. A companion flanges can be supplied as an individual component or as assemblies with universal drive shafts. It allows connection of a flange yoke to another type of connection, for proper torque transmission. In the present work Structural analysis on the flange was performed to obtain the areas of maximum stress under the given boundary conditions. The present study also reports the comparison of experimental and modeling results. It is observed that the deformation is reduced by 3.2% through modeling study and 3% through Experimental study. It is also observed that AISI 204 material is better than SAE 1141 material. Keywords: UTM, ANSYS Workbench, CREO 2.0, Companion flange

Ensure a safe, long life and efficient combustion within a diesel engine is an important challenge in the applications of engine technology. Much research has been done on thermal stress within engine cylinders and on engine piston heads, and how to reduce some of this stress in order to prevent failure or increase the life of the engine. The failure of a piston head tends to occur from it enduring the gas effect of the high pressures and temperatures. By performing static and dynamic Finite Element Analysis (FEA) on a piston mechanism of a diesel engine proper dimensions for different parts of an engine can be determined and failure of an engine in service can be avoided. In this research finite element analysis has been performed to determine the total deformation, stresses, and other parameters that are essential from design point of views. Real world input data for simulation obtained from running an existing diesel engine have been effectively used. Static structural and dynamic reaction of a piston assembly under the applied load of internal combustion in a diesel engine were closely observed. ANSYS workbench was utilized to perform these simulations. Using SolidWorks a piston assembly model consisting of the piston, connecting pin, connecting rod, cylinder head, crankshaft, and cranks was designed and used for simulation. Simulation results were being collected from the static structural and rigid body dynamics modules. The static structural simulation was conducted in order to obtain the structural response of the piston assembly under the combustion phase. This simulation was intended to replicate the pressure forces applied to the piston assembly at the moment of combustion. A pressure force of 7 MPa was applied to the top of the piston. From the simulation results, the maximum total deformation 1.9 mm occurred at the top edge of the piston head on the same side as the combustion chamber. Maximum equivalent Von Mises stress 323.9 MPa occurred at the joint of the connecting rod and crankshaft and the minimum equivalent stress 27 kPa occurred at the bottom of the connecting rod. Principal stresses were also examined, where the maximum principal stress 335.1 MPa occurred at the joint of the connecting rod and crankshaft and the minimum principal stress 63.5 MPa occurred inside of the connecting rod joint. The maximum shear stress 177.7 MPa occurred at the joint of the connecting rod and crankshaft and the minimum shear stress 14.26 kPa occurred at the bottom of the connecting rod. Two types of forces were considered acting upon the geometry in the rigid body dynamic simulation, one is standard earth gravity and the other is a linear dynamic load of 55,000 N applied to the top of the piston head which is used to simulate the act of combustion within the combustion chamber of a cylinder. From the rigid dynamic simulation, it was found that after the first combustion cycle, the linear velocity of the entire system, acceleration of the entire system, and the crank angular velocity reach to the maximum of 24.77 m/s, 17684 m/s2 and 5487 rpm respectively at 0.0187 seconds. Then after the second combustion cycle, the linear velocity of the entire system and the crank angular velocity reach to 27.56 m/s and 6043 rpm respectively at 0.0481 seconds; however the acceleration of the entire system took 0.0551 seconds to reach to 30115 m/s2.

This investigation aimed to predict the temperature distribution in the inlet and exhaust valve and isotherms to the cooling media at a given load of a diesel engine. For the analysis that has been done a Tata- Mercedes diesel engine with 90 mm bore diameter and Stroke length of 120 mm was analysed using FEM through Ansys workbench 15.0. Steady as well as transient cases were considered in combination. The temperature distribution and isotherms are computed and plotted using Ansys. The results obtained by Ansys workbench 15.0 were satisfactory and were in line when compared with finite differential analysis. There is a large temperature variation along the length of the valve. It may vary from 560 °C to 110 °C from tip to valve head in the exhaust valve while this variation is less in the case of inlet valve from 540 °C to 100 °C from the face to the tip. The linear temperature difference between the nodes at the base of the stem to the node at the center of the face increases with time and acquires the maximum value of about 120 °C at about 10 s then it decreases till the valve attains a steady state value. Thus, was observed from analysis that during this time there is a maximum probability of failure of valves due to linear differences in temperature.

This article presents a new electromagnetic linear actuator applied in the electromagnetic-driven valve train. To clarify the actuator’s temperature rise and heat distribution, a heat transfer mode...

Models with main-branch channel, crossing channel and net type channel are established and nutrient liquid with a velocity of 0.01m/s is adopted in the study to investigate the fluid field in the channel by using FEA software FLUENT. The velocity and pressure distribution have been obtained in the investigation. By comparing the results in the three models, pressure and velocity distribution in the second and the third models are relatively uniform and are appropriate for the bionics principles. Studies in this paper will be of benefits for the development of tissue engineering.

Solutions are presented for the dynamic axial forces developed by pump-impeller-shroud surfaces. A bulk-flow model of the leakage path between the impeller and the housing is used for the analysis consisting of the path-momentum, circumferential-momentum, and continuity equations. Shear stresses at the impeller and housing surfaces are modeled according to Hirs’ turbulent lubrication model. The governing equations were developed earlier to examine lateral rotordynamic forces developed by impellers. A perturbation expansion of the governing equations in the eccentricity ratio yields a set of zeroth and first-order governing equations. The zeroth-order equations define the leakage rate, velocity distributions, and the pressure distribution for a centered impeller position. The first-order equations define the perturbations in the velocity and pressure distributions due to axial motion of the impeller. Integration of the perturbed pressure and shear-stress distribution acting on the rotor yields the reaction forces acting on the impeller face. Calculated results yield predictions of resonance peaks of the fluid within the annulus formed by the impeller shroud and housing. Centrifugal acceleration terms in the path-momentum equation are the physical origin of these unexpected predictions. For normalized tangential velocities at the inlet to the annulus, uθo(0) = Uθo(0)/Riω of 0.5, the phenomenon is relatively minor. As uθo(0) is increased to 0.7, sharper peaks are predicted. The fluid modes are well damped in all cases. Numerical results are presented for a double-suction single-stage pump which indicate that the direct stiffness of the perturbed impeller shroud forces are negligible. Small but appreciable added-mass and damping terms are developed which have a modest influence on damping and peak-amplitude excitation frequency. The forces only became important for pumps with very low axial natural frequencies in comparison to the running speed, viz., ten percent of the running speed or lower.

The pressure drops and flow characteristics in a diffuser fitted with a semi-dimpled tube are numerically studied. Air is selected as a working fluid and its physical properties are modelled using pressure and velocity distribution. The study reveals that every semi-dimple acts as a vortex generator. They provide the flow with intensive vortices between the dimpled surface and the diffuser wall. Therefore, they cause an enhancement in the pressure drop inside the diffuser. The performance of the dimples consisting of sphere type dimples with 5 mm in diameter. Three “Reynolds number” operated in the range of 25000 ˂Re˂ 50000 that is based on the hydraulic diameter of the diffuser Dh. The variation in Reynolds number is examined to further investigations of the pressure drop and flow characteristics of the diffuser. The numerical simulations are conducted using incompressible steady-state Reynolds Averaged Navier Stokes equations and the turbulence model “RNG k-e is utilized in the current study. The flow characteristics of the diffuser with semi-dimpled tube are analysed and compared in terms of pressure contour, velocity profile, and velocity vectors, at the operating range of Reynolds numbers. The results are discussed to point out the flow structure mechanisms. It is found that equipping the diffuser with a semi-dimpled tube leads to an increase in the recirculation and vortices inside and near the dimples area. Therefore, they have a considerable influence on the flow field. For the diffuser equipped with a semi-dimpled tube, it is noted that the flow characteristics depend on the Reynolds number. The pressure drop in the flow direction becomes lower with increasing Reynolds number. The findings indicate that for the semi-dimples, increasing Reynolds number increases the velocity distribution significantly due to better mixing of the air.

In a power plant that uses seawater as a coolant, a debris filter (DF) is required to remove foreign substances from the seawater, and differential pressure leads to a decrease in the coolant flow rate, leading to a decrease in the power generation efficiency. In this study, an analysis was performed for the cases wherein the initial flow velocity conditions of the DF used in the condenser tube cleaning system (CTCS) were 1.5 m/s, 2.0 m/s, and 2.5 m/s using Ansys Fluent 2021, and the flow characteristics were identified. The flow and differential pressure characteristics of a CTCS with an installed DF were considered in a comparative analysis of the velocity, pressure, and turbulence kinetic energy (TKE) distributions. The results confirmed that a vortex was generated in the pipe with the DF, apparently due to the collision of the flow with the bracket of the DF. As the flow rate increased, the range of the vortex increased, causing a loss in flow.

High-fidelity numerical investigation on structural integrity of SFR fuel cladding during design basis events

컨테이너 크레인의 설계 시 적용되는 하중 조건 중에서 풍하중이 가장 중요하게 고려되어지는바, 본 연구는 75m/s의 풍하중이 컨테이너 크레인에 작용 할 때 컨테이너 크레인의 구조적 안정성에 미치는 영향을 보다 정확하게 예측하기 위하여 유동-구조 연성해석을 실시하였다. 컨테이너 크레인에 작용하는 실제 유동현상을 고려하기 위하여 먼저 전산유동해석을 실시하였으며, 이를 통해서 얻어진 풍하중을 구조해석의 하중조건으로 적용하는 유동-구조 연성해석을 통하여 컨테이너 크레인 각 지지점에서의 반력을 도출하고 그 결과를 분석하였다. 사용된 모델은 주변 환경으로 인하여 컨테이너 크레인의 최대 고도가 제한 될 경우 사용되는 관절형 컨테이너 크레인이며 전산유동해석 및 유동-구조 연성해석 프로그램으로는 ANSYS ICEM CFD 10.0과 ANSYS CFX 10.0을 사용하였다. This study was carried out to the effect of wind load on the structural stability of an articulated type container crane according to the wind direction assuming that 75m/s wind velocity is applied on a container crane using FSI(fluid-structural interaction). To consider fluid phenomenon around the container crane, the wind load was derived by the computation fluid dynamic, and it applied to the FSI which can guarantee an accuracy and a reliability in the design stage for wind resistant structural stability to minimize the damage due to high wind load applied in a container crane with a 'ㄱ' type articulated boom which used in the total height restriction region. Following from this, the reaction force on the each support of a container crane was suggested. ANSYS ICEM CFD 10.0 and ANSYS CFX 10.0 used for computation fluid dynamic, and the ANSYS Workbench 11.0 was used for the fluid-structural interaction.

ABSTRACTIn this study, an improved fluid–structure interaction (FSI) analysis method is developed for a flapping wing. A co-rotational (CR) shell element is developed for its structural analysis. Further, a relevant non-linear dynamic formulation is developed based on the CR framework. Three-dimensional preconditioned Navier–Stokes equations are employed for its fluid analysis. An implicit coupling scheme is employed to combine the structural and fluid analyses. An explicit investigation of a 3D plunging wing is conducted using this FSI analysis method. A further investigation of this plunging wing is performed in relation to its operating condition. In addition, the relation between the wing’s aerodynamic performance and plunging motion is investigated.