Influence of the barrier discharge on the aerodynamic drag of the Zhukovskii airfoil under various air flow conditions

The influence of the dielectric barrier discharge plasma on the total aerodynamic drag of the Zhukovskii airfoil has been investigated. With the use of the Pitot–Prandtl tube the velocity distribution of discharge-induced ion wind at a distance of 18 mm from the trailing edge of the airfoil has been measured experimentally. It has been shown that the influence of the discharge leads to a decrease in the aerodynamic drag by a value from 10 to 34% depending on the incident flow parameters and the operating conditions of the discharge system.     

Comparative creep damage assessments using the various models

The creep fracture characteristics of a conventionally cast (CC) MARM-002 superalloy were studied for creep conditions of 1173 K/200–400 MPa using different approaches including the Kachanov-Rabotnov type continuum damage mechanics, grain boundary damage accumulation, and Chen-Argon diffusional cavity growth. A rapid improvement in creep rupture life can be achieved by reducing the Kachanov-Rabotnov damage rate () below a critical value of this rate. It is possible that a large improvement in creep resistance would be made by decreasing grain boundary damage rate rather than continuum damage rate since the minimum creep rate (_m) accelerates rapidly without changing the parameter .     

Evaluating the efficiency of drying with various means of energy supply

We present results from experimental research into the drying of cardboard roofing material under various forms of energy input. We have undertaken a comparative analysis of various means of drying in terms of energy efficiency. We have demonstrated the usefulness of an expanded industrial application of the convective method of energy supply in the drying of fiber strand materials.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 60, No. 3, pp. 442–448, March, 1991.     

Effect of local energy supply to a hypersonic flow on the drag of bodies with different nose bluntness

Parameters of the axisymmetric flow around bodies with different bluntness are compared in the case of constant energy supply to the main hypersonic flow. Flow structures, drag coefficients, and expenditure of energy on overcoming drag are analyzed with the effect of thermal energy on the flow taken into account for different bodies with equal volume.     

Comparative analysis of numerically derived drag models for development of bed expansion ratio correlation in a bubbling fluidized bed

For designing and operating fluidized bed reactors, bed expansion ratio is one of the most important parameters. In this research, a bubbling fluidized bed is simulated using three-dimensional Eulerian-Eulerian method that is incorporated with kinetic theory of granular flow (KTGF) to calculate the pressure drop, gas volume fraction (GVF) and bed expansion ratio. Grid optimization is firstly conducted to achieve suitable solution for further simulations. Subsequently, different numerically derived drag models are employed to investigate the effect of these models on gas-solid flow dynamics. Afterwards, the fluidized bed is simulated at different gas superficial velocities employing two different drag models respectively. Simulation results have been comprehensively validated against experimental data. Finally, an expression for bed expansion ratio has been formulated and compared with the empirical correlation. The proposed correlation holds reasonably well with various experimental values. This work provides a scalable way to aid in designing and operating process reactors.     

Comparative analysis of turbulence models

A comparative analysis is performed for a complete locally anisotropic turbulence model of the second order and existing turbulence models. The comparison draws on experimental data, data of a direct numerical simulation of the nonstationary Navier-Stokes equations for a developed channel flow and a uniform channel flow with a constant velocity shift, and results for turbulence damping behind a grid. The K-ɛ model and the quasi-isotropic turbulence model are shown to have marked disadvantages, especially in describing turbulent flows with a high degree of anisotropy of pulsatory motion. Use of a locally anisotropic turbulence model improves the accuracy of determining Reynolds stresses. Consideration is given to the advantages and disadvantages of the turbulence models discussed. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 2, pp. 328–339, March—April, 2000.     

Numerical evaluation of the transonic wave drag integral

This article describes-a new method, suitable for use on a digital computer, for evaluating the singular double integral of Hayes which determines the transonic wave drag of a slender body. Comparison with known exact results and with an earlier computer program described by Eminton shows the present method to be accurate as well as economic in computer time.     

Comparative analysis of energy resources

This paper examines the problems encountered by a growing demand for energy consumption and a dwindling reserve of conventional energy sources Development of alternative clean energy sources should be vigorously pursued in order to improve or maintain the quality of life. The search for new energy sources has indicated the need for developing approaches to evaluate feasibility and competitiveness of the alternative sources. Frequently mentioned as alternative energy sources are wind power, water power, tidal power, coal, fission energy with or without breeders, geothermal energy, ocean thermal energy conversion, low temperature solar energy, solar power through photosynthesis and solar electric: generation. Factors considered in comparing these energy sources are given. An illustration based on United States energy consumption rates and available energy resources provide revealing information about future directions in energy production.

Requirements for economic comparative models are discussed and an example is given.     

Comparative study of various approaches to stochastic elastic wave propagation

Summary Three approaches to the problem of 1-D wave propagation in media with random elastic and mass properties are studied: (i) method of integral spectral decomposition, (ii) the Fokker-Plank-Kolmogorov equation, and (iii) the Dyson integral equation. Merits and shortcomings of each approach are discussed. It is shown that the approaches cover actually all possible problems of the harmonic wave propagation in heterogeneous or stochastic media, hence, by means of a preliminary analysis of a particular problem and bearing in mind the strong and weak sides of each approach, one can choose an appropriate solution strategy.Dedicated to Prof. Dr. Dr. h. c. Franz Ziegler on the occasion of his 60th birthdayOn leave from Department of Mechanics and Control Processes, State Technical University of St. Petersburg, Russia.     

Dynamic Boolean modelling reveals the influence of energy supply on bacterial efflux pump expression

Antimicrobial resistance (AMR) is a global health issue. One key factor contributing to AMR is the ability of bacteria to export drugs through efflux pumps, which relies on the ATP-dependent expression and interaction of several controlling genes. Recent studies have shown that significant cell-to-cell ATP variability exists within clonal bacterial populations, but the contribution of intrinsic cell-to-cell ATP heterogeneity is generally overlooked in understanding efflux pumps. Here, we consider how ATP variability influences gene regulatory networks controlling expression of efflux pump genes in two bacterial species. We develop and apply a generalizable Boolean modelling framework, developed to incorporate the dependence of gene expression dynamics on available cellular energy supply. Theoretical results show that differences in energy availability can cause pronounced downstream heterogeneity in efflux gene expression. Cells with higher energy availability have a superior response to stressors. Furthermore, in the absence of stress, model bacteria develop heterogeneous pulses of efflux pump gene expression which contribute to a sustained sub-population of cells with increased efflux expression activity, potentially conferring a continuous pool of intrinsically resistant bacteria. This modelling approach thus reveals an important source of heterogeneity in cell responses to antimicrobials and sheds light on potentially targetable aspects of efflux pump-related antimicrobial resistance.     

Influence of the energy supply on the conditions of supersonic flow around an obstacle

Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 62, No. 2, pp. 243–247, February, 1992.     

Comparative analysis of energy absorption behavior of tapered and grooved thin-walled tubes with the various geometry of the cross section

ABSTRACT

In this paper, Crush force efficiency (CFE), Specific Energy Absorption (SEA), Energy Absorption per Crush Length (E_cl), Maximum and average crush forces of straight and grooved tapered thin-walled tubes with various cross-section shapes (circle, ellipse, square, rectangle, hexagon, and octagon) have been studied. The effects of taper, the groove (as initiator) and their interaction have been presented in the current study using Finite Element Method as a numerical method. The tubes have the same volume, height, average cross-section area, thickness and material and have been subjected to axial and oblique dynamic loading. The results of simulations show that the section's geometry, taper and groove addition have a significant effect on energy absorption behavior and the hexagon cross section have better energy absorption behavior compared with other considered geometries. On the other hand, it was found that the behavior of these structures could improve against dynamic axial and oblique impact loading with the cost-effective geometry modifications. These results could help to improve and choose appropriate energy absorber structure based on desirable crush force and energy absorbing characteristics.     

Comparative study of various methods of primary energy estimation in nucleon-nucleon interactions

The various available methods for the estimation of primary energy in nucleon-nucleon interactions have been examined by using the experimental data on angular distributions of shower particles from p-N interactions at two accelerator energies, 67 and 400 GeV. Three different groups of shower particle multiplicities have been considered for interactions at both energies. It is found that the different methods give quite different estimates of primary energy. Moreover, each method is found to give different values of energy according to the choice of multiplicity groups. It is concluded that the E_ch method is relatively the better method among all the methods available, and that within this method, the consideration of the group of small multiplicities gives a much better result. The method also yields plausible estimates of inelasticity in high energy nucleon-nucleon interactions.     

振荡浮子式波能转换装置动力输出系统特性研究

动力输出系统(Power Take-Off, PTO)作为波浪能转换装置(Wave Energy Converter, WEC)的主要构件之一,对系统运动及能量转换至关重要。首先基于势流理论,运用特征函数展开法得到圆柱形浮体所在流域的速度势函数级数表达式,进而通过边界匹配法得到作垂荡运动浮子的附加质量、阻尼系数及波浪激励力的解析表达式。针对阻尼器特性,分别研究线性和非线性PTO阻尼作用下,浮子的运动及波能转换特性,重点研究了线性PTO作用下的过阻尼问题。计算结果表明,低速度指数的PTO系统对装置运动的影响主要体现在PTO阻尼系数上,随着阻尼系数增大,波能装置的共振频率逐渐减小,但减小幅度很小;PTO系统的非线性特性并不能改变浮子的最优转换效率,但是较大的速度指数能有效改善PTO系统的阻尼容量;在较低频和较高频时,通过解析算法得到的最优PTO阻尼系数会使得装置处于过阻尼工作状态,且在低频部分需要进行最优PTO修正的最高频率和在高频部分需要进行修正的最低频率均随着半径和吃水的增大而逐渐减小。     

Experimental investigation of the methods of energy supply to the external surface of models of flying vehicles

The results of investigation of the effects of external supply of energy to the wind tunnel models at the Mach number M=5 are presented. The energy supply has been modeled by a light gas (helium) supply to the models. The loads have been measured by wind-tunnel balance. It is obtained that at small angles of attack the lift increment under the external supply of energy occurs without an increase in drag and under some conditions is more efficient than the lift increase by means of higher engine thrust under the same energy supply to it. The similarity criterion (“influence coefficient”) is proposed to relate the wind tunnel results to full-scale conditions. Based on the fact that the application of hot hydrogen is the most reasonable for the external supply of energy under full-scale conditions, the aspects of accelerating its ignition and combustion at low temperatures are investigated. It is shown that addition into the hydrogen of its atoms and activated molecules by passing the hydrogen through a glow-discharge zone makes it possible to implement ignition at a temperature of ∼300 K. Without such a treatment, ignition occurs at a temperature of ∼900 K.     

Assessing wave energy effects on biodiversity: the wave hub experience

Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative.     

Investigation of the influence of polymer admixtures on the magnitude of the local drag coefficient

Experimental data are presented on the influence of polyox-admixtures in an aqueous solution on the magnitude of the local drag coefficients. Theoretical and experimental results on determining the pressure drop in a pump during the flow of polymer solutions in a real hydraulic apparatus are compared.     

Reducing the wave drag of bodies in supersonic flows using porous materials

We have experimentally studied the effect of a gas-permeable material situated in front of a blunt body on the aerodynamic drag of this system in a supersonic airflow with a Mach number of M = 4.85. It is established that the porous material significantly reduces the wave drag in the system. Explanation of the observed phenomenon is proposed.     

Statistical analysis of models of liquid mixing in various hydrodynamic conditions

A statistical analysis has been made of the distribution functions for residence time of a liquid in different flow formulations. The region of application of the different models of longitudinal dispersion is discussed.