Experimental and Numerical Analysis of the Transient Behavior of the Oil De-Congealing Process in an Aero Fuel-Cooled Oil Cooler Under Low-Temperature Conditions

2021 ◽  
Author(s):  
Foster Kwame Kholi ◽  
Jaehyun Park ◽  
Kyeongho Lee ◽  
Man Yeong Ha ◽  
Michael Klingsporn ◽  
...  
Keyword(s):  
Low Temperature ◽  
Boundary Conditions ◽  
Critical Role ◽  
Transient Behavior ◽  
Analysis Model ◽  
Practical Applications ◽  
Fuel Flow ◽  
Commercial Code ◽  
Study Results ◽  
Oil Cooler

Abstract The fuel-cooled oil cooler (FCOC) in the lubrication circuit plays a critical role in the aero gas-turbine engine's aerothermal management. However, the low temperature of the operating environment can congeal the oil and reduce the FCOC efficiency. The oil bypass valve (OBV) installed on the FCOC prevents pressure loss. Its failure may cause overheating, requiring preemptive performance prediction. Experimental and numerical analyses were used to evaluate the cooler's de-congealing performance under typical boundary conditions of pressure and temperature, OBV configurations, and re-routing of feed oil and fuel flow paths. The temporal variation of oil and fuel mass flow rates, temperature, and pressure of the feed oil and fuel provided an insight into the de-congealing process and duration. The experimental data were used to develop a one-dimensional (1D) flow and thermal network analysis model based on the effectiveness (e)-NTU method to predict the transient oil de-congealing performance of the FCOC. The customized commercial code predicted the de-congealing phenomena using empirical correlations with property correction schemes, showing good agreement with the experiment. The findings revealed various ways to enhance the de-congealing performance of the FCOC. The study results showed that the operating boundary conditions, OBV location and status, and flow arrangements affect de-congealing behavior and time. The present numerical model provides results quickly and can effectively predict experimentally costly and complicated cases. The attempted estimates of steady heat rejection and detailed methodology could guide future studies and practical applications.

An Analysis Model and its Practical Applications in PG&E Gas Transmission Pipeline Strength Test Projects

2018 ◽  
Author(s):  
Chunlei He ◽  
Edward Stracke
Keyword(s):  
Critical Role ◽  
Ideal Gas ◽  
Strength Test ◽  
Future Application ◽  
Test Duration ◽  
Test Medium ◽  
Analysis Model ◽  
Practical Applications ◽  
Pipeline Section ◽  
Strength Tests

This article presents a complete set of calculations (referred to as Model) PG&E developed to monitor, assess and approve strength tests on insitu (pipelines currently in service) gas transmission pipelines. How the Model is used in the field, 2017 test results, and process improvements that resulted from the implementation of the model are also discussed. In compliance with CPUC directives, the Code of Federal Regulations[1] and PG&E’s internal standards, PGE has performed strength tests on approximately 1,100 miles of insitu pipelines from 2011 through 2017. The model was specifically designed to assess the strength test of a closed section of gas pipeline for both leaks and ruptures. The model was originally designed for strength tests using water as the test medium and updated to accommodate nitrogen as a test medium. A future enhancement will be to incorporate a blend of Nitrogen and Helium as the test medium. The model plots the pressure-temperature and pressure-volume curves over the test duration (field test measurements) and compares them to the theoretically calculated curves. The curves are used to determine if the change in pressure is due to temperature influence or leakage. When water is the test medium, the model calculates the net corrected medium volume change from start to end of the static test period. When nitrogen is the test medium, the model calculates and analyzes net mass change of the medium by considering nitrogen under both the real gas state and the ideal gas state. By calculating restrained (buried) pipeline section and unrestrained (exposed) pipeline section separately, the model gains more accuracy. Accurate temperature measurements play a critical role in the model. The model makes it possible for engineers to monitor, analyze and direct strength tests with real-time test data. The model is also used to evaluate the pipeline fill condition on the day prior to the actual test, which resulted in fewer test restarts due to incomplete fill or temperature stabilization issues. An additional benefit is the tests were typically completed earlier in the day. The model is utilized on all PG&E insitu pipeline strength projects today. Authors also provide improvement suggestions of this model in future application.

Analysis of Flexibility and Stability of Crane Telescopic Boom with Elastic Restraint and Second-Order Effect

2013 ◽  
Vol 774-776 ◽  
pp. 109-113
Author(s):  
Liang Du ◽  
Nian Li Lu ◽  
Peng Lan
Keyword(s):  
Stability Analysis ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Order Effect ◽  
Second Order ◽  
Analysis Model ◽  
Characteristic Equations ◽  
Lateral Deflection ◽  
Practical Applications ◽  
Vertical Stability

The cylinder support crane telescopic booms deformation and stability analysis model in the lifting plane is equivalent with the multistep column with elastic restraint. To analyze the lateral flexibility and vertical stability of the telescopic booms with elastic restraint accurately, this paper established the deflection differential equations of multi-sectioned telescopic booms with second-order effect, introduced proper boundary conditions, obtained the precise recurrence lateral deflection differential equations and the buckling characteristic equations of arbitrary sectioned telescopic booms, and some practical applications of the buckling characteristic equations were presented. Took certain five-sectioned telescopic booms as example, by comparing the results with ANSYS method, the accuracy of the equations deduced in this paper was verified.

scholarly journals Effect of Drop Orientation on Structural Integrity of a Shipping Container for Nuclear Fresh Fuel

2020 ◽  
Vol 162 ◽  
pp. 03002
Author(s):  
Supil Ryu ◽  
Joohong Chun ◽  
Namgyu Park ◽  
Seungjae Lee
Keyword(s):  
Structural Integrity ◽  
Time Integration ◽  
Nonlinear Dynamic Analysis ◽  
Transient Behavior ◽  
Computer Code ◽  
Nuclear Industry ◽  
Analysis Model ◽  
Design Modification ◽  
Shipping Container ◽  
Study Results

A shipping container of fresh fuel in nuclear industry is used to prevent a leakage of unirradiated radioactive materials and to maintain an integrity of nuclear fuels during transportation. In this study, the drop behavior was predicted and the effect of drop orientation on structural integrity of a shipping container in case of 9 m free drop was studied. LS-DYNA which is a computer code designed to perform nonlinear dynamic analysis using explicit time integration was used in numerical analyses. The material properties were applied to the analysis model to predict the nonlinear transient behavior and three kinds of drop orientations were considered. The analysis results such as accelerations, reaction forces and internal assembly deformations were compared for each case in terms of the containment and confinement systems. Test results showed that a significant impact energy was absorbed by the polyurethane foam and shock absorbers. The drop orientations that have the greatest impact on the containment and confinement systems were Case 1 and Case 3, respectively. Through this study, these study results can be applicable to the container design modification and the shipping container development.

Response Law and Influencing Factors of the Soil under Action of Pile Driving Vibration Based on Midas/GTS

2013 ◽  
Vol 353-356 ◽  
pp. 979-983
Author(s):  
Dong Zhang ◽  
Jing Bo Su ◽  
Hui De Zhao ◽  
Hai Yan Wang
Keyword(s):  
Damping Ratio ◽  
Large Diameter ◽  
Time History ◽  
Pile Driving ◽  
Analysis Model ◽  
Vibration Load ◽  
History Analysis ◽  
Study Results ◽  
Propagation Law ◽  
Dynamic Time

Due to the upgrade and reconstruct of a high-piled wharf, the piling construction may cause the damage of the large diameter underground pipe of a power plant nearby. For this problem, a dynamic time-history analysis model was established using MIDAS/GTS program. Based on the analysis of the pile driving vibration and its propagation law, some parameters, such as the modulus of the soil, the Poissons ratio of soil, the action time of vibration load and the damping ratio of the soil that may have an effect on the response law of the soil, were studied. The study results not only serve as an important inference to the construction of this case, but also accumulate experience and data for other similar engineering practices.

Two-dimensional metal carbides and nitrides (MXenes): preparation, property, and applications in cancer therapy

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2125-2145 ◽  
Author(s):  
Lu Ming Dong ◽  
Cui Ye ◽  
Lin Lin Zheng ◽  
Zhong Feng Gao ◽  
Fan Xia
Keyword(s):  
Cancer Therapy ◽  
Scientific Community ◽  
Critical Role ◽  
High Specific Surface Area ◽  
Future Perspective ◽  
Two Dimensional ◽  
Metal Carbides ◽  
Practical Applications ◽  
Two Dimensional Materials ◽  
Size And Morphology

AbstractTransition metal carbides and nitrides (MXenes), which comprise a rapidly growing family of two-dimensional materials, have attracted extensive attention of the scientific community, owing to its unique characteristics of high specific surface area, remarkable biocompatibility, and versatile applications. Exploring different methods to tune the size and morphology of MXenes plays a critical role in their practical applications. In recent years, MXenes have been demonstrated as promising nanomaterials for cancer therapy with substantial performances, which not only are helpful to clarify the mechanism between properties and morphologies but also bridge the gap between MXene nanotechnology and forward-looking applications. In this review, recent progress on the preparation and properties of MXenes are summarized. Further applications in cancer therapy are also discussed. Finally, the current opportunities and future perspective of MXenes are described.

scholarly journals A neutral core of degressively proportional allocations under lexicographic preferences of agents

2021 ◽  
Author(s):  
Katarzyna Cegiełka ◽  
Piotr Dniestrzański ◽  
Janusz Łyko ◽  
Arkadiusz Maciuk ◽  
Maciej Szczeciński
Keyword(s):  
European Union ◽  
Numerical Analysis ◽  
Theoretical Analysis ◽  
Boundary Conditions ◽  
Case Studies ◽  
The European Union ◽  
Practical Applications ◽  
Lexicographic Preferences ◽  
Degree Of Acceptance ◽  
Feasible Solutions

AbstractOne of the main problems of practical applications of degressively proportional allocations of goods and burdens is lack of uniqueness of this principle. Even under given boundary conditions of allocation, i.e. determined minimal and maximal amounts of a good that can be assigned in a given allocation, there are usually many feasible solutions. The lack of formal rules of allocation is the reason why the allocation is typically a result of negotiations among its agents. A number of allocations favor some of agents or their groups, therefore other agents cannot accept them. The aim of this paper is to indicate a way of reducing the set of all feasible solutions exclusively to those that are neutral to all agents. As a result of the term of lexicographic preference of allocation agents defined on the basis of the relation theory followed by a numerical analysis of sets of all feasible solutions, it is possible to determine a core of this set in the form of a subset of all feasible solutions that are acceptable by all agents. In addition, this subset can be further divided into smaller subsets with regard to the degree of acceptance of their elements. Theoretical analysis is complemented by case studies, one of which is application of this idea to the allocation of seats in the European Parliament among the member states of the European Union.

scholarly journals A Unified Spectro-Geometric-Ritz Method for Vibration Analysis of Open and Closed Shells with Arbitrary Boundary Conditions

2016 ◽  
Vol 2016 ◽  
pp. 1-30 ◽  
Author(s):  
Dongyan Shi ◽  
Yunke Zhao ◽  
Qingshan Wang ◽  
Xiaoyan Teng ◽  
Fuzhen Pang
Keyword(s):  
Boundary Conditions ◽  
Vibration Analysis ◽  
Ritz Method ◽  
Free Vibration Analysis ◽  
Analysis Model ◽  
Arbitrary Boundary ◽  
Fourier Cosine ◽  
Auxiliary Functions ◽  
Arbitrary Boundary Conditions ◽  
Closed Shells

This paper presents free vibration analysis of open and closed shells with arbitrary boundary conditions using a spectro-geometric-Ritz method. In this method, regardless of the boundary conditions, each of the displacement components of open and closed shells is represented simultaneously as a standard Fourier cosine series and several auxiliary functions. The auxiliary functions are introduced to accelerate the convergence of the series expansion and eliminate all the relevant discontinuities with the displacement and its derivatives at the boundaries. The boundary conditions are modeled using the spring stiffness technique. All the expansion coefficients are treated equally and independently as the generalized coordinates and determined using Rayleigh-Ritz method. By using this method, a unified vibration analysis model for the open and closed shells with arbitrary boundary conditions can be established without the need of changing either the equations of motion or the expression of the displacement components. The reliability and accuracy of the proposed method are validated with the FEM results and those from the literature.

Progress of Research on Welding for Molybdenum Alloys

2014 ◽  
Vol 33 (3) ◽  
pp. 193-200 ◽  
Author(s):  
Jiteng Wang ◽  
Juan Wang ◽  
Yajiang Li ◽  
Deshuang Zheng
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Low Temperature ◽  
Welded Joint ◽  
Structural Materials ◽  
Practical Applications ◽  
Traditional Technology ◽  
Molybdenum Alloys ◽  
Resistance To Oxidation ◽  
Temperature Applications

AbstractMolybdenum and molybdenum alloys are considered to be attractive structural materials for high-temperature applications. However, molybdenum alloys are sensitive to gas impurities and have the characteristics of low temperature embrittlement and less resistance to oxidation at elevated temperature. The toughness and strength of welded joint is not easy to be ensured by traditional technology. Recently, many efforts have been made to join molybdenum and its alloys. In this paper, we present the result of investigations on welding methods of molybdenum and its alloys and overview the practical applications in engineering. The key of joining molybdenum alloys is to improve the toughness of welded joint and prevent the generation of pores and cracks.

An ICA Algorithm Based on Symmetric and Asymmetric Generalized Gaussian Model

2011 ◽  
Vol 204-210 ◽  
pp. 470-475
Author(s):  
Feng Zhao ◽  
Yun Jie Zhang ◽  
Min Cai
Keyword(s):  
Independent Component Analysis ◽  
Gradient Method ◽  
Gaussian Model ◽  
Component Analysis ◽  
Independent Component ◽  
Blind Signal Separation ◽  
Natural Gradient ◽  
Analysis Model ◽  
Practical Applications ◽  
Source Signal

Maximum likelihood estimation is a very popular method to estimate the independent component analysis model because of good performance. Independent component analysis algorithm (the natural gradient method) based on this method is widely used in the field of blind signal separation. It potentially assumes that the source signal was symmetrical distribution, in fact in practical applications, source signals may be asymmetric. This article by distinguishing that the source signal is symmetrical or asymmetrical, proposes an improved natural gradient method based on symmetric generalized Gaussian model (People usually call generalized Gaussian model) and asymmetric generalized Gaussian model. The random mixed-signal simulation results show that the improved algorithm is better than the natural gradient separation method.

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