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Modelling internal air systems ingas turbine engines

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航空动力学报 2007年第4期22卷 505-520页

作者： j.michael owen Department of Mechanical Engineering University of Bath

Rotating-disc systems can be used to model,experimentally and computationally,the flow and heat transfer that occur inside the internal cooling-air systems of gas turbine *** rotating-disc systems have been used successfully to simplify and understand some of the complex flows that occur in internal-air systems,and designers have used this insight to improve the cooling effectiveness,thereby increasing the engine efficiency and reducing the *** this review paper,three important cases are considered:hot-gas ingress;the pre-swirl system;and buoyancy-induced ***,or ingestion,occurs when hot gas from the mainstream gas path is ingested into the wheel-space between the turbine disc and its adjacent *** seals are fitted at the periphery of the system,and sealing flow is used to reduce or prevent ***,too much sealing air reduces the engine efficiency,and too little can cause serious overheating,resulting in damage to the turbine rim and blade *** the flow is three-dimensional and unsteady,there are encouraging signs that simple ‘orifice models’ could be used to estimate the amount of ingress into the *** a pre-swirl system,the cooling air for the gas-turbine blades is swirled by stationary nozzles,and the air is delivered to the blades via receiver holes in the rotating turbine *** the air reduces its temperature relative to the rotating blades,and the designer needs to calculate the air temperature and pressure drop in the *** designer also needs to calculate the effect of this swirling flow on the heat transfer from the turbine disc to the air,as this has a significant effect on the temperature distribution and stresses in the *** experimental and computational studies have given a better understanding of the flow and heat transfer in these ***-induced flow occurs in the cavity between two co-rotating compressor discs when the temperature of the discs is higher than

关键词：燃气涡轮机车空气动力学数学模型旋转式圆盘系统

SIMAP500: A novel risk score to identify recipients at higher risk of hepatocellular carcinoma recurrence following liver transplantation

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World journal of Transplantation 2024年第3期14卷 132-143页

作者： Amr Alnagar Nekisa Zakeri Konstantinos Koilias Rosemary E Faulkes Rachel Brown owen Cain M Thamara P R Perera Keith j Roberts Rebeca Sanabria-Mateos David C Bartlett Yuk Ting Ma Shivan Sivakumar Shishir Shetty Tahir Shah Bobby V M Dasari Department of HBP and Liver Transplantation Surgery Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Centre for Liver Research Institute of Biomedical ResearchBirmingham B152TTUnited Kingdom Department of Hepatology Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Department of Pathology University Hospitals Birmingham NHS Foundation TrustBirmingham B152GWUnited Kingdom Department of Oncology Queen Elizabeth HospitalUniversity Hospitals of BirminghamBirmingham B152GWUnited Kingdom

BACKGROUND Recurrence of hepatocellular carcinoma(HCC)following liver transplantation(LT)has a devastating influence on recipients’survival;however,the risk of recur-rence is not routinely *** stratification is vital with a long LT waiting time,as that could influence the recurrence despite strict listing *** This study aims to identify predictors of recurrence and develop a novel risk pre-diction score to forecast HCC recurrence following *** A retrospective review of LT for HCC recipients at University Hospitals Bir-mingham between july 2011 and February *** and multivariate analyses were performed to identify recurrence predictors,based on which the novel SIMAP500(satellite nodules,increase in size,microvascular invasion,AFP>500,poor differentiation)risk score was *** 234 LTs for HCC were performed with a median follow-up of 5.3 *** developed in 25 patients(10.7%).On univariate analyses,RETREAT score>3,α-fetoprotein(AFP)at listing 100-500 and>500,bridging,increased tumour size between imaging at the listing time and explant histology,increase in the size of viable tumour between listing and explant,presence of satellite nodules,micro-and macrovascular invasion on explant and poor differentiation of tumours were significantly associated with recurrence,based on which,the SIMAP500 risk score is *** SIMAP500 demonstrated an excellent predictive ability(c-index=0.803)and outper-formed the RETREAT score(c-index=0.73).SIMAP500 is indicative of the time to disease *** SIMAP500 risk score identifies the LT recipients at risk of HCC *** stratification allows patient-centric post-transplant surveillance *** validation of the score is recommended.

关键词： Liver transplantation Hepatocellular carcinoma Recurrence Survival

整级透平中转静轮缘封严问题研究PartⅠ:封严与入侵

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工程热物理学报 2014年第5期35卷 873-877页

作者：吴康任静蒋洪德 j.michael owen 清华大学热能工程系北京100084 University of Bath UK BA2 7AY

本文通过构建由一级动静叶组成的外流影响下的轮缘密封问题的实验和数值模型,针对燃气轮机透平转静轮盘间隙的封严与入侵问题开展了研究。其中第一部分主要关注燃气入侵的主要影响因素,入侵气体在腔室内部的分布规律和最小封严流量。结... 详细信息

本文通过构建由一级动静叶组成的外流影响下的轮缘密封问题的实验和数值模型,针对燃气轮机透平转静轮盘间隙的封严与入侵问题开展了研究。其中第一部分主要关注燃气入侵的主要影响因素,入侵气体在腔室内部的分布规律和最小封严流量。结果表明:静叶尾缘的压力分布是造成燃气入侵的主要原因,即在主流的压力大于密封腔室内压力的区域会出现燃气侵入腔室,造成局部温度过高;主流压力小于腔室内部的压力区域,密封气体能够较好的封严转静间隙。入侵气体和封严气体的掺混主要发生在腔内高半径处并在高速旋转的动盘引发的夹带作用下深入腔室内部低半径处。因此在轮缘密封的结构设计中需要全面的考虑这些因素的影响。

关键词：整级透平转静轮缘封严与入侵动盘夹带效应

Fifty years of finite elements——a solid mechanics perspective

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Theoretical & Applied Mechanics Letters 2012年第5期2卷 1-5页

作者： D.R.j.owen Civil and Computational Engineering Centre Swansea University

The finite element method has been considered as one of the most significant engineering advances of the twentieth century. This computational methodology has made substantial impact on many fields in science and also has profoundly changed engineering design procedures and practice. This paper, mainly froln a solid mechanics perspective, and the Swansea viewpoint in particular, describes very briefly the origin of the methodology, then summaries selected milestones of the technical developments that have taken place over the last fifty years and illustrates their application to some practical engineering problems.

关键词： inite elements isoparametric representation elasto-plasticity finite strain mesh adaptiv ity discrete and multi-fracturing modelling

PARALLEL ANALYSIS OF COMBINED FINITE/DISCRETE ELEMENT SYSTEMS ON PC CLUSTER

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Acta Mechanica Sinica 2004年第5期20卷 534-540页

作者：王福军 Y.T.FENG D.R.j.owen 张静刘洋 College of Water Conservancy & Civil Eng. China Agricultural UniversityBeijing 100083China Civil & Computational Engineering Centre University of Wales SwanseaSwanseaSA2 8PPU.K.

A computational strategy is presented for the nonlinear dynamic analysis of large- scale combined finite/discrete element systems on a PC *** this strategy,a dual-level domain decomposition scheme is adopted to implement the dynamic domain *** domain decomposition approach perfectly matches the requirement of reducing the memory size per processor of the *** treat the contact between boundary elements in neighbouring subdomains,the elements in a subdomain are classified into internal,interfacial and external *** this way,all the contact detect algorithms developed for a sequential computation could be adopted directly in the parallel *** examples show that this implementation is suitable for simulating large-scale *** typical numerical examples are given to demonstrate the parallel efficiency and scalability on a PC cluster.

关键词： parallel computation finite element discrete element PC cluster

EXPERIMENTAL AND NUMERICAL RESEARCH ON BULLDOZER WORKING PROCESS

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Chinese journal of Mechanical Engineering 2007年第2期20卷 41-46页

作者： LI Yanjie XU Yong HUANG Wenbin FENG Y T owen D R j College of Science China Agricultural University Beijing 100083 China Civil ＆ Computational Engineering Center University of Wales Swansea Swansea SA2 8PP UK

A simulative analysis coupled with experiment on behaviors of a soil bed cut by a model bulldozer blade is carried out using the finite element/distinct element method（FE/DEM） facility built in the ELFEN package. Before simulation, tensile/compression, triaxial compression and the soil specimens are examined through uniaxial direct shear tests to obtain model characteristics and relevant parameters, then soil cutting experiments are carried out via a mini-soil bin system with a soil bed of 60/120 mm in width and 10 mm in depth cut by a 1/9 scale model bulldozer blade moving with the velocity of 10 mm/s. The soil constitutive model includes the tensile elastic model for tensile breakage and the compressive elastoplastic relationship with Mohr-Coulomb criterion. The cutting length in simulation is set as 1/4 of that in the experiment divided into 1 869 triangular elements. The comparison between the simulated results and experimental ones shows that the used model is capable of analyzing soil dynamic behaviors qualitatively, and the predicted fracturing profiles in general conform to the experiment. Hence the feasibility for analyzing soil fracturing behaviors in tillage or other similar processes is validated.

关键词： Finite element method Discrete element method Finite element/distinct element method(FE/DEM) Soil Bulldozer

Quantifying geological uncertainty in metamorphic phase equilibria modelling;a Monte Carlo assessment and implications for tectonic interpretations

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Geoscience Frontiers 2016年第4期7卷 591-607页

作者： Richard M.Palin owen M.Weller David j.Waters Brendan Dyck Institute of Geosciences Johannes-Gutenberg University Mainz55128MainzGermany Geological Survey of Canada 601 Booth StreetOttawaONKIA OESCanada Department of Earth Sciences University of OxfordOxfordOX1 3ANUnited Kingdom

Pseudosection modelling is rapidly becoming an essential part of a petrologist＇s toolkit and often forms the basis of interpreting the tectonothermal evolution of a rock sample, outcrop, or geological region. Of the several factors that can affect the accuracy and precision of such calculated phase diagrams, ＂geological＂ uncertainty related to natural petrographic variation at the hand sample- and/or thin section-scale is rarely considered. Such uncertainty influences the sample＇s bulk composition, which is the primary control on its equilibrium phase relationships and thus the interpreted pressure-temper- ature （P-T） conditions of formation. Two case study examples--a garnet-cordierite granofels and a garnet-staurolite-kyanite schist--are used to compare the relative importance that geological uncer- tainty has on bulk compositions determined via （1） X-ray fluorescence （XRF） or （2） point counting techniques. We show that only minor mineralogical variation at the thin-section scale propagates through the phase equilibria modelling procedure and affects the absolute P-T conditions at which key assemblages are stable. Absolute displacements of equilibria can approach ＋l kbar for only a moderate degree of modal proportion uncertainty, thus being essentially similar to the magnitudes reported for analytical uncertainties in conventional thermobarometry. Bulk compositions determined from multiple thin sections of a heterogeneous garnet-staurolite-kyanite schist show a wide range in major-element oxides, owing to notable variation in mineral proportions. Pseudosections constructed for individual point count-derived bulks accurately reproduce this variability on a case-by-case basis, though averaged proportions do not correlate with those calculated at equivalent peak P-T conditions for a whole-rock XRF-derived bulk composition. The main discrepancies relate to varying proportions of matrix phases （primarily mica） relative to porphyroblasts （primarily staurolite and kyanit

关键词： Geological uncertainty Error Pseudosection Monte Carlo MnNCKFMASHTO

Modelling of Magnetorheological Fluids with Combined Lattice Boltzmann and Discrete Element Approach

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Communications in Computational Physics 2010年第5期7卷 1095-1117页

作者： K.Han Y.T.Feng D.R.j.owen Civil and Computational Engineering Centre School of EngineeringSwansea UniversitySA28PPUK

A combined lattice Boltzmann and discrete element approach is proposedfor numerical modelling of magnetorheological fluids. In its formulation, the particledynamics is simulated by the discrete element method, while the fluid field is resolvedwith the lattice Boltzmann method. The coupling between the fluid and the particlesare realized through the hydrodynamic interactions. Procedures for computing magnetic, contact and hydrodynamic forces are discussed in detail. The applicability ofthe proposed solution procedure is illustrated via a two-stage simulation of a MR fluidproblem with four different particle volume fractions. At the first stage, simulationsare performed for the particle chain formation upon application of an external magnetic field;and at the second stage, the rheological properties of the MR fluid underdifferent shear loading conditions are investigated with the particle chains establishedat the first stage as the initial configuration.

关键词： Magnetorheological fluids particle dynamics rheological properties magnetic interaction models lattice Boltzmann method discrete element method

Effect of inductively coupled plasma surface treatment on silica gel and mesoporous MCM-41 particles

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Plasma Science and Technology 2018年第6期20卷 104-113页

作者： j A jUAREZ-MORENO U CHACON-ARGAEZ j BARRON-ZAMBRANO C CARRERA-FIGUEIRAS P QUINTANA-owen W TALAVERA-PECH Y PEREZ-PADILLA A AVILA-ORTEGA facultad de ingeniería química-uady periférico norte kilómetro 33.5col.chuburna de hidalgo inn C.P. 97203 Mérida Yucatan México centro de investigación y de estudios avanzados del ipn-unidad mérida km.6 antigua carretera a progreso apdo. Postal 73 Cordemex 97310 Méfida Yucatán México

Silica gel and MCM-41 synthesized mesoporous materials were treated with either oxygen（O_2）,hexamethyldisiloxane（HMDSO） and organic vapors like ethanol（Et OH）,and acrylonitrile（AN）inductive *** radiofrequency power for the modification was fixed to 120 W and30 min,assuring a high degree of organic ionization energy in the *** surface properties were studied by infrared spectroscopy（FTIR）,scanning electron microscopy,x-ray photoelectron spectroscopy and dynamic light scattering technique was used for characterizing size *** the silica and MCM-41 particles were modified by AN and HMDSO plasma gases,the surface morphology of the particles was changed,presenting another color,size or *** contrast,the treatments of oxygen and Et OH did not affect the surface morphology of both particles,but increased the oxygen content at the surface bigger than the AN and HMDSO plasma *** this study,we investigated the influence of different plasma treatments on changes in morphology and the chemical composition of the modified particles which render them a possible new adsorbent for utilization in sorptive extraction techniques for polar compounds.

关键词： silica MCM-41 nanoparticles plasma treatment