Experimental Improvement of Ejector Performance Through Numerical Optimization of Nozzle Geometry

2013 ◽  
Author(s):  
Navid Sharifi ◽  
Majid Sharifi
Keyword(s):  
Optimization Procedure ◽  
Nozzle Geometry ◽  
Cfd Models ◽  
Steam Ejector ◽  
Nominal Pressure ◽  
Fixed Constant ◽  
Nozzle Geometries ◽  
The One ◽  
Suction Flow ◽  
The Given

Ejectors are widely used in different applications such as refrigeration, propulsion, evacuation and aerospace. They use a pressurized flow as a motive stream to entrain a secondary flow or suction flow. In the current study, a malfunctioning steam ejector is studied experimentally to identify the sources of low compression ratio. This ejector was designed to operate under a motive pressure of 6 bar. However, the required vacuum in the system was not attained unless the pressure of motive steam was increased to 8 bar. The steam ejector was coupled with other unit operating facilities and hence, the ejector replacement was very costly. Therefore, the fastest and the most inexpensive way of improving the device performance was considered as replacing just the primary nozzle and without any further change in ejector’s geometry. To achieve the required vacuum under the available motive pressure (i.e. 6 bar), a CFD–based optimization procedure was performed and different nozzle shapes were numerically investigated. The CFD Models were constrained to a fixed constant throat since the optimized nozzle shall not consume more flow rate than the former one. Ten different nozzle geometries were scrutinized in this numerical simulation and the one, which yields the highest entraining performance under the given boundary condition (i.e. motive flow pressure of 6 bar), was selected as the most optimized nozzle and manufactured. After installing the designed nozzle, an improved entrainment capability was observed and a desired vacuum level was attained under the nominal pressure of 6 bar.

scholarly journals Novell Application of CFD for Rocket Engine Nozzle Optimization

2018 ◽  
Vol 47 (2) ◽  
pp. 131-135
Author(s):  
Csaba Jéger ◽  
Árpád Veress
Keyword(s):  
Simulation Model ◽  
Rocket Engine ◽  
Pressure Ratio ◽  
Geometry Optimization ◽  
Optimization Procedure ◽  
Geometric Optimization ◽  
Nozzle Geometry ◽  
Nozzle Contour ◽  
Nozzle Geometries ◽  
Optimization Loop

Numerical analyses, validation and geometric optimization of a converging-diverging nozzle flows has been established in the present work. The optimal nozzle contour for a given nozzle pressure ratio and length yields the largest obtainable thrust for the conditions and thus minimises the losses. Application of such methods reduces the entry cost to the market, promote innovation and accelerate the development processes. A parametric geometry, numerical mesh and simulation model is constructed first to solve the problem. The simulation model is then validated by using experimental and computational data. The optimizations are completed for conical and bell shaped nozzles also to find the suitable nozzle geometries for the given conditions. Results are in good agreement with existing nozzle flow fields. The optimization loop described and implemented here can be used in the all similar situations and can be the basis of an improved nozzle geometry optimization procedure by means of using a multiphysics system to generate the final model with reduced number sampling phases.

THE EU SUGAR MARKET PROFILE AND ITS MAIN DRIVERS

2015 ◽  
Author(s):  
Lubos SMUTKA ◽  
Irena BENEŠOVÁ ◽  
Patrik ROVNÝ ◽  
Renata MATYSIK-PEJAS
Keyword(s):  
Market Failure ◽  
Current System ◽  
Quota System ◽  
Considerable Debate ◽  
Sugar Market ◽  
The Common ◽  
The One ◽  
Production Capacities ◽  
The Given ◽  
The Eu

Sugar is one of the most important elements in human nutrition. The Common Market Organisation for sugar has been a subject of considerable debate since its establishment in 1968. The European agricultural market has been criticized for its heavy regulations and subsidization. The sugar market is one of the most regulated ones; however, this will change radically in 2017 when the current system of production quotas will end. The current EU sugar market changed is structure during the last several decades. The significant number of companies left the market and EU internal sugar market became more concentrated. The aim of this paper is presentation characteristics of sugar market with respect to the supposed market failure – reduction in competition. The analysis also identifies the main drivers and determinants of the EU especially quota sugar market. In relation to paper’s aim the following results are important. The present conditions of the European sugar market have led to market failure when nearly 75 % (10 million tonnes) of the quota is controlled by five multinational companies only. These multinational alliances (especially German and French one) are also taking control over the production capacities of their subsidiaries. In most countries, this causes serious problems as the given quota is controlled by one or two producers only. This is a significant indicator of market imperfection. The quota system cannot overcome the problem of production quotas on the one hand and the demand on the other; furthermore, it also leads to economic inefficiency. The current EU sugar market is under the control of only Sudzucker, Nordzucker, Pfeifer and Langen, Tereos and ABF.

Quasi-Periodic Control Technique for Minimizing Fuel Consumption During Record Vehicle Competition

2013 ◽  
Vol 60 (2) ◽  
pp. 185-197 ◽  
Author(s):  
Paweł Sulikowski ◽  
Ryszard Maronski
Keyword(s):  
Fuel Consumption ◽  
Optimal Control Theory ◽  
Slope Angle ◽  
Control Technique ◽  
Decision Variables ◽  
Aeronautical Engineering ◽  
The One ◽  
Optimal Driving ◽  
The Given ◽  
Engine Power

The problem of the optimal driving technique during the fuel economy competition is reconsidered. The vehicle is regarded as a particle moving on a trace with a variable slope angle. The fuel consumption is minimized as the vehicle covers the given distance in a given time. It is assumed that the run consists of two recurrent phases: acceleration with a full available engine power and coasting down with the engine turned off. The most fuel-efficient technique for shifting gears during acceleration is found. The decision variables are: the vehicle velocities at which the gears should be shifted, on the one hand, and the vehicle velocities when the engine should be turned on and off, on the other hand. For the data of students’ vehicle representing the Faculty of Power and Aeronautical Engineering it has been found that such driving strategy is more effective in comparison with a constant speed strategy with the engine partly throttled, as well as a strategy resulting from optimal control theory when the engine is still active.

"THE SYNTHESIS OF WAR AND THEATRE": SOCIO-HUMANITARIAN DISCOURSE ON THE ESSENCE OF TERRORISM

2020 ◽  
pp. 10-23
Author(s):  
Irina V Malygina ◽  
◽  
Anna V Malygina ◽  
Keyword(s):  
International Terrorism ◽  
Complex Nature ◽  
Cultural Resources ◽  
Self Presentation ◽  
The Status ◽  
World Cultural Heritage ◽  
The One ◽  
Strategic Object ◽  
The Given

The article reveals the heuristic potential of social and humanitarian knowledge in understanding the complex nature of terrorism. The given research optics allows to expand traditional frameworks of considering terrorism as a phenomenon caused by political, ideological and economic factors; to reveal and substantiate deep cultural and mental reasons of the given phenomenon; make sense of terrorism as a destructive form of cultural identity. The cultural and historical origins of modern terrorism, which is closely connected with radical Islam, are analyzed in the civilizational system of coordinates “West–East”. The system of argumentation is based on scientific concepts and current artistic practices that interpret the causes of inter-civilizational tension resulting in international terrorism. The change of the status of the artist in the “epoch of terrorism” is analyzed; the theme of theatricalization and aestheticization of terrorist actions and the role of media in these processes are problematized. As a newest trend, which has not received any serious theoretical reflection, the text considers the phenomenon conditionally designated as “sublimation of terrorist activity into a symbolic sphere”, which is manifested in the destruction of monuments of world cultural heritage, in the orientation to culture as a new strategic object of terrorist attacks, on the one hand, and the use of cultural resources for self-presentation and promotion of their ideology by terrorist organizations, on the other

Influence of Food and Larval Age on the Defensive Chemistry of Satumia pyri

2001 ◽  
Vol 56 (1-2) ◽  
pp. 89-94 ◽  
Author(s):  
Reinhold Deml
Keyword(s):  
Body Fluids ◽  
The Other ◽  
Larval Diet ◽  
Larval Instars ◽  
Defensive Chemistry ◽  
Crataegus Monogyna ◽  
Secondary Compound ◽  
Influence Of Food ◽  
The One ◽  
The Given

Abstract Scolus secretions and hemolymph of caterpillars of Satumia pyri fed with two different foodplants (Crataegus monogyna, Prunus spinosa) were chemically analyzed and their chemical similarities determined. The secondary-compound patterns obtained for the two body fluids showed no significant differences when compared between the two groups of alterna­ tively fed last-instar larvae. Thus, the composition of these fluids of full-grown caterpillars is not influenced by the larval diet. However, younger larvae on P. spinosa revealed a diversity of compounds differing significantly from that of larger caterpillars fed with either C. mono­gyna (both body fluids) or P. spinosa (hemolymph only). This indicates that, on the one hand, the hemolymph composition is adapted to the changing physiological requirements of the given instars whereas, on the other hand, the defensive mixtures remain unaltered in the late larval instars due to a constant spectrum of potential enemies.

Multidimensional regular C-fraction with independent variables corresponding to formal multiple power series

2019 ◽  
Vol 150 (4) ◽  
pp. 1853-1870 ◽  
Author(s):  
R. I. Dmytryshyn
Keyword(s):  
Power Series ◽  
Continued Fractions ◽  
Numerical Experiments ◽  
The Other ◽  
Independent Variables ◽  
Classical Algorithm ◽  
Multiple Power ◽  
The One ◽  
The Given ◽  
Multiple Power Series

AbstractIn the paper the correspondence between a formal multiple power series and a special type of branched continued fractions, the so-called ‘multidimensional regular C-fractions with independent variables’ is analysed providing with an algorithm based upon the classical algorithm and that enables us to compute from the coefficients of the given formal multiple power series, the coefficients of the corresponding multidimensional regular C-fraction with independent variables. A few numerical experiments show, on the one hand, the efficiency of the proposed algorithm and, on the other, the power and feasibility of the method in order to numerically approximate certain multivariable functions from their formal multiple power series.

scholarly journals REAL PRODUCT SIZE ACCOUNTING PROBLEM AT WAVE DEFORMATION HARDENING

2020 ◽  
Vol 2020 (1) ◽  
pp. 4-10
Author(s):  
Andrey Kirichek ◽  
Sergey Barinov ◽  
Aleksandr Yashin ◽  
Aleksey Zaycev ◽  
Aleksandr Konstantinov
Keyword(s):  
Deformation Pattern ◽  
Product Size ◽  
Wave Deformation ◽  
Processing Modes ◽  
Deformation Hardening ◽  
Different Shapes ◽  
The One ◽  
The Impact ◽  
The Given ◽  
Geometrical Dimensions

The article raises the problem of the need to take into account real dimensions when they are strengthened by wave deformation. The fact is that in carrying out initial calculations the overall dimensions of the models under study are quite often neglected. On the one hand, this makes it possible to significantly simplify the calculation of the flat model, and on the other - to exclude consideration of the influence of geometric dimensions of the sample on the process to be followed. This is especially relevant in the study of shock systems in which wave processes lie. The effect of the final samples on the hardening process should not be excluded. This is because the elastic-stic deformation pattern has its own features. Hardening is carried out due to transmission of energy in the form of deformation wave, which is transformed on all gras with variable acoustic rigidity, including on boundaries, which are final dimensions of the analysed sample. Preliminary studies have developed a significant effect on the process of wave deformation hardening of geometrical dimensions of the material to be treated, since at equal volumes of strengthened materials and processing modes different distribution of microassay in the surface layer is observed. The established algorithm of further research of the given direction will allow not only to reveal the regularities of through strengthening of samples of different shapes and sizes, but also to establish the possibility of contactless de-formation strengthening of the sides of the sample opposite to the impact of the HRD, which have a complex profile shape, as well as the possibility of contactless deformation strengthening of internal hard-to-reach surfaces.

Dimensionality and Construct Validity of a Video-Based, Objective Personality Test for the Assessment of Willingness to Take Risks in Road Traffic

2005 ◽  
Vol 97 (1) ◽  
pp. 309-320 ◽  
Author(s):  
Martin E. Arendasy ◽  
Andreas Hergovich ◽  
Markus Sommer ◽  
Bettina Bognar
Keyword(s):  
Construct Validity ◽  
Personality Trait ◽  
Road Traffic ◽  
Personality Test ◽  
Traffic Situation ◽  
One Dimensional ◽  
First Results ◽  
The One ◽  
The Given ◽  
Homeostasis Theory

The study at hand reports first results about the dimensionality and construct validity of a newly developed objective, video-based personality test, which assesses the willingness to take risks in traffic situations. On the basis of the theory of risk homeostasis developed by Wilde, different traffic situations with varying amounts of objective danger were filmed. These situations mainly consisted of situations with passing maneuvers and speed choice or traffic situations at intersections. Each of these traffic situations describes an action which should be carried out. The videos of the traffic situations are presented twice. Before the first presentation, a short written explanation of the preceding traffic situation and a situation-contingent reaction is provided. The respondents are allowed to obtain an overview of the given situations during the first presentation of each traffic situation. During the second presentation the respondents are asked to indicate at which point the action that is contingent on the described situation will become too dangerous to carry out. Latencies for items were recorded as a measure for the magnitude of the person's subjectively accepted willingness to take risks in the sense of the risk homeostasis theory by Wilde. In a study with 243 people with different education and sex, the one-dimensionality of the test corresponding to the latency model by Scheiblechner was investigated. Analysis indicated that the new measure assesses a one-dimensional latent personality trait which can be interpreted as subjectively accepted amount of risk (target risk value). First indicators for the construct validity of the test are given by a significant correlation with the construct-related secondary scale, adventurousness of the Eysenck Personality Profiler with, at the same time, nonsignificant correlations to the two secondary scales, extroversion and emotional stability, that are not linked to the construct.

Improving the accuracy of the synthesis of the amplitude-phase distribution in an antenna array with an arbitrary geometry

2021 ◽  
Author(s):  
D.D. Gabrielyan ◽  
Dan.S. Fedorov ◽  
Den.S. Fedorov
Keyword(s):  
Antenna Arrays ◽  
Phase Distribution ◽  
Problem Statement ◽  
Arbitrary Geometry ◽  
Radiating Element ◽  
Path Measurement ◽  
The One ◽  
The Given ◽  
Single Approach

Problem statement. One of the constructing antenna arrays (AA) topic is related to the determination of complex amplitudes at the input of the antenna-feeder path, which, taking into account the distortions introduced by the its, ensure the formation of an amplitude-phase distribution (APD), in which the formed DP differed minimally from the set one. The statement of the problem assumes the known number and coordinates of the location of the emitters, the DP of the radiating element in the composition of the radiating opening, a given radiation pattern. It is required to form an APD in a given opening of the AA, which ensures the formation of a DP that has a minimum deviation from the specified one. To solve the problem, the following algorithm is proposed: determination of the APD at the input of the antenna-feeder path, which ensures the formation of a given DP in the absence of distortions introduced by the antenna-feeder path; measurement for the selected directions of the generated DP with the selected APD in the presence of APD distortions introduced by the antenna-feeder path; formation of a refined APD that ensures the fulfillment of required condition in the presence of distortions introduced by the antenna-feeder path of the AA. Objective. Minimize the root-mean-square deviation of the generated PD from the one specified for the AP with the opening of an arbitrary geometry. Results. The results obtained showed: The formulation of the problem of synthesis of the APD allows us to consider, within the framework of a single approach, AA with different geometries, including AA with a non-planar radiating opening, no restrictions are imposed on the shape of the boundary, and linear (quasi-ring) AA, the emitters of which are located along an arbitrary mane. Using the proposed algorithm for the synthesis of APD, which includes three main stages: the formation of APD for a given DP; measurement of complex values of the generated DP; refinement of the APD by determining the corrections while minimizing the standard deviation (SD) between the specified and formed at the first stage of the DP, allows us to form an APD that provides a minimum SD between the specified and formed DP. The performed studies have shown that when choosing the number of angular directions in each plane, comparable to the number of emitters in this plane, there is a large difference between the given and formed DP. When the number of angular directions for measuring the DP is approximately three times greater than the number of emitters in a given plane, the SD between the specified and formed DP is close to the minimum value and practically does not change with further increase.

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