scholarly journals Distribution of kinetic energy losses between nozzles and turbine impeller on partial gas supply modes

2021 ◽  
pp. 122-126
Author(s):  
Ю.В. Соломахин ◽  
Л.П. Цыганкова ◽  
В.Н. Коршунов
Keyword(s):  
Kinetic Energy ◽  
Pressure Ratio ◽  
Experimental Studies ◽  
Average Diameter ◽  
Rotor Blades ◽  
Low Flow ◽  
Energy Losses ◽  
Outlet Section ◽  
Technical Literature ◽  
Actual Flow Rate

В статье приведены результаты экспериментальных исследований связанных с распределением потерь кинетической энергии между сопловым аппаратом и рабочим колесом у осевых малорасходных турбинных ступеней. У всех ступеней конструктивные углы выхода сопел были менее 9°, что повлекло за собой необходимость выполнения рабочих колес с относительным шагом установки рабочих лопаток значительно большим, рекомендованного в технической литературе. Исследования проведены для ступеней со средним диаметром 250 мм. Диапазон изменения факторов составил: отношение давлений перед соплами к давлению за ступенью от 2.0 до 5.0; частоты вращения вала с рабочим колесом от 0 до 14000 . Эффективность использования кинетической энергии приведена в виде коэффициентов скорости соплового аппарата и рабочего колеса. Коэффициенты представляют собой отношение реальной скорости потока на выходе из соплового аппарата (рабочего колеса) к теоретически возможной скорости газа в выходном сечении рассматриваемого элемента ступени. Выявлено, что коэффициенты скорости сопловых аппаратов и рабочих колес изменяются не только при смене режимных параметров, таких как частота вращения ротора и отношения давлений на ступень, но и при изменении степени парциальности ступени. The article presents the results of experimental studies related to the distribution of kinetic energy losses between the nozzle apparatus and the impeller at axial low-flow turbine stages. At all stages, the design angles of the nozzle exit were less than 9 °, which entailed the necessity of making impellers with a relative pitch of the rotor blades that was much larger, as recommended in the technical literature. The studies were carried out for steps with an average diameter of 250 mm. The range of variation of the factors was the ratio of the pressures in front of the nozzles to the pressure behind the stage from 2.0 to 5.0; rotation speed of the shaft with the impeller from 0 to 14000 rpm. The efficiency of using the kinetic energy is given in the form of the coefficients of the speed of the nozzle apparatus and the impeller. The coefficients represent the ratio of the actual flow rate at the outlet of the nozzle apparatus (impeller) to the theoretically possible gas velocity in the outlet section of the stage element under consideration. It was found that the speed coefficients of the nozzle apparatus and impellers change not only when changing operating parameters, such as the rotor speed and the pressure ratio per stage, but also when changing the degree of stage partiality.

Сomparative analysis of the calculation results of infiltration losses on the example of a residential building in Moscow

2019 ◽  
Vol 1 (2) ◽  
pp. 63-72
Author(s):  
Ju. S. Gribach ◽  
D. S. Gribach ◽  
O. I. Poddaeva
Keyword(s):  
Energy Efficiency ◽  
Construction Industry ◽  
Experimental Studies ◽  
Energy Losses ◽  
Construction Sites ◽  
Technical Literature ◽  
Regulatory Documents ◽  
Calculation Results ◽  
The Russian Federation ◽  
Using Data

Today, the problem of energy efficiency is one of the leading positions in world politics. On the territory of the Russian Federation, a sufficient number of regulatory documents in the construction industry have been developed and put into effect, which regulate the activities of designers and builders in the field of energy efficiency, including in matters of energy losses. However, today this direction is not sufficiently developed: more than 10 % is spent on air heating during infiltration, while the process itself requires the most detailed study. On the basis of scientific and technical literature, the staff of the National Research Moscow State University of Civil Engineering concluded that there is a dependence of air infiltration on the distribution of the velocity of wind flows along the building facades. It was also determined that the calculation of infiltration losses on the methods available to date overstates the results, which leads to large economic losses during construction. In this regard, a study of infiltration losses was carried out using data obtained from experimental studies of wind effects on the construction site. The article presents a brief methodology for carrying out this study, a description of the process of the experiment, as well as a comparison of the data obtained in the calculation according to SP 50.13330.2012, GOST R 55656-2012 and GOST R 55656-2012 with the results of an experimental study.Introduction:the regulatory documents used in the construction industry on the territory of the Russian Federation that regulate the activities of designers and builders in the field of energy efficiency, including in matters of energy losses, are described. An analysis of the technical literature regarding the subject under study is also presented, including issues related to heat losses and infiltration.Methods:methods for calculating infiltration losses according to SP 50.13330.2012, GOST R 55656-2013 and GOST R 55656-2013 are described using data on the aerodynamic characteristics of buildings obtained in the course of experimental studies of wind impact on buildings. A brief algorithm for performing physical modeling of air flow to construction sites, which was developed by the staff of the Educational, Scientific and Production Laboratory for aerodynamic and aeroacoustic testing of building structures of the National Research University MGSU, is presented.Results and discussions:the approbation of this research methodology is presented, and a comparative graph of the calculation results for all three methods is given on the example of a residential complex under construction in Moscow.Conclusion:the conclusion is made about the need to conduct experimental studies of wind impact on construction sites in order to obtain more accurate results of the calculation of infiltration.

Effect of Vaned Diffuser on a Modified Turbocharger Centrifugal Compressor Performance

2014 ◽  
Vol 663 ◽  
pp. 347-353
Author(s):  
Layth H. Jawad ◽  
Shahrir Abdullah ◽  
Zulkifli R. ◽  
Wan Mohd Faizal Wan Mahmood
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Width Ratio ◽  
Outlet Section ◽  
Suction Surface ◽  
Vaned Diffuser ◽  
Minimum Width

A numerical study that was made in a three-dimensional flow, carried out in a modified centrifugal compressor, having vaned diffuser stage, used as an automotive turbo charger. In order to study the influence of vaned diffuser meridional outlet section with a different width ratio of the modified centrifugal compressor. Moreover, the performance of the centrifugal compressor was dependent on the proper matching between the compressor impeller along the vaned diffuser. The aerodynamic characteristics were compared under different meridional width ratio. In addition, the velocity vectors in diffuser flow passages, and the secondary flow in cross-section near the outlet of diffuser were analysed in detail under different meridional width ratio. Another aim of this research was to study and simulate the effect of vaned diffuser on the performance of a centrifugal compressor. The simulation was undertaken using commercial software so-called ANSYS CFX, to predict numerically the performance charachteristics. The results were generated from CFD and were analysed for better understanding of the fluid flow through centrifugal compressor stage and as a result of the minimum width ratio the flow in diffuser passage tends to be uniformity. Moreover, the backflow and vortex near the pressure surface disappear, and the vortex and detachment near the suction surface decrease. Conclusively, it was observed that the efficiency was increased and both the total pressure ratio and static pressure for minimum width ratio are increased.

scholarly journals A Comparative Assessment of Spalart-Shur Rotation/Curvature Correction in RANS Simulations in a Centrifugal Pump Impeller

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ran Tao ◽  
Ruofu Xiao ◽  
Wei Yang ◽  
Fujun Wang
Keyword(s):  
Kinetic Energy ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Comparative Assessment ◽  
Turbulence Kinetic Energy ◽  
Low Flow ◽  
Pump Impeller ◽  
Curvature Correction ◽  
Centrifugal Pump Impeller ◽  
Low Flow Rate

RANS simulation is widely used in the flow prediction of centrifugal pumps. Influenced by impeller rotation and streamline curvature, the eddy viscosity models with turbulence isotropy assumption are not accurate enough. In this study, Spalart-Shur rotation/curvature correction was applied on the SSTk-ωturbulence model. The comparative assessment of the correction was proceeded in the simulations of a centrifugal pump impeller. CFD results were compared with existing PIV and LDV data under the design and low flow rate off-design conditions. Results show the improvements of the simulation especially in the situation that turbulence strongly produced due to undesirable flow structures. Under the design condition, more reasonable turbulence kinetic energy contour was captured after correction. Under the low flow rate off-design condition, the prediction of turbulence kinetic energy and velocity distributions became much more accurate when using the corrected model. So, the rotation/curvature correction was proved effective in this study. And, it is also proved acceptable and recommended to use in the engineering simulations of centrifugal pump impellers.

scholarly journals Improving the efficiency of carousel wind turbine using aerodynamic shield

2021 ◽  
Vol 2119 (1) ◽  
pp. 012093
Author(s):  
A F Serov ◽  
V N Mamonov ◽  
A D Nazarov ◽  
N B Miskiv
Keyword(s):  
Kinetic Energy ◽  
Flow Velocity ◽  
Air Flow ◽  
Cylindrical Body ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Heat Generator ◽  
Axis Of Rotation ◽  
Wheel Torque ◽  
Air Flow Velocity

Abstract The problem of increasing the efficiency of using the oncoming air flow for a wind wheel with a vertical axis of rotation, which is a mechanical drive of the wind heat generator, is considered. It is proposed to increase the efficiency of the device by installing an aerodynamic shield for the air flow oncoming the wind wheel. Such a shield is a cylindrical body in which a heat generator is placed. The shield creates an effect of confuser, leading to an increase in the speed and, consequently, in the kinetic energy of the air flow acting on the rotor blades. It is shown experimentally that the presence of an aerodynamic shield under the conditions of the experiments carried out at an incoming air flow velocity of ~ 1 m/s leads to a practical doubling of the wind wheel torque.

Methods for calculating thermal processes under conditions of natural convection of gaseous methane under the influence of electrostatic fields

2021 ◽  
Author(s):  
V.A. Altunin ◽  
K.V. Altunin ◽  
M.R. Abdullin ◽  
M.R. Chigarev ◽  
I.N. Aliev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Power Plants ◽  
Experimental Studies ◽  
Thermal Processes ◽  
Technical Literature ◽  
New Methods ◽  
Electric Wind ◽  
Electrostatic Fields ◽  
General Method

Relying on the review and analysis of scientific and technical literature, as well as the results of experimental studies, we developed new methods for calculating thermal processes occurring in gaseous methane during its natural convection, under the influence of electrostatic fields. In this study we show methods for calculating and determining the coefficients of heat transfer to gaseous methane under the influence of electric wind, as well as methods for calculating and determining the effect of electrostatic fields on the negative process of sedimentation on a heated experimental working plate in the volume of gaseous methane. A general method has been developed for the effective and safe application of electrostatic fields in gaseous methane, which must be carried out in the calculations, design, creation, and operation of new engines, power plants, and techno systems for single and reusable ground, air, aerospace and space-based aircraft.

Quick Start of an Industrial Gas Turbine Engine Through the Development of “Silent Start” VGV Schedule

2020 ◽  
Author(s):  
Senthil Krishnababu ◽  
Vili Panov ◽  
Simon Jackson ◽  
Andrew Dawson
Keyword(s):  
Guide Vane ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Start Time ◽  
Turbine Engine ◽  
High Pressure Ratio ◽  
Compressor Map ◽  
Industrial Gas Turbine

Abstract In this paper, research that was carried out to optimise an initial variable guide vane schedule of a high-pressure ratio, multistage axial compressor is reported. The research was carried out on an extensively instrumented scaled compressor rig. The compressor rig tests carried out employing the initial schedule identified regions in the low speed area of the compressor map that developed rotating stall. Rotating stall regions that caused undesirable non-synchronous vibration of rotor blades were identified. The variable guide vane schedule optimisation carried out balancing the aerodynamic, aero-mechanical and blade dynamic characteristics gave the ‘Silent Start’ variable guide vane schedule, that prevented the development of rotating stall in the start regime and removed the non-synchronous vibration. Aerodynamic performance and aero-mechanical characteristics of the compressor when operated with the initial schedule and the optimised ‘Silent Start’ schedule are compared. The compressor with the ‘Silent Start’ variable guide vane schedule when used on a twin shaft engine reduced the start time to minimum load by a factor of four and significantly improved the operability of the engine compared to when the initial schedule was used.

Dynamic Model of Multistage Centrifugal Compressor With a Stage-by-Stage Anti-Surge Recirculating System

2021 ◽  
Author(s):  
Nicola Casari ◽  
Michele Pinelli ◽  
Alessio Suman ◽  
Matteo Manganelli ◽  
Mirko Morini ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Suction Side ◽  
System Level ◽  
Low Flow ◽  
Return Flow ◽  
Control Line ◽  
Compressor Surge ◽  
Surge Control ◽  
Surge Line

Abstract The operability region of a centrifugal compressor is bounded by the low-flow (or high-pressure ratio) limit, commonly referred to as surge. The exact location of the surge line on the map can vary depending on the operating condition and, as a result, a typical Surge Avoidance Line is established at 10% to 15% above the stated flow for the theoretical surge line. The current state of the art of centrifugal compressor surge control is to utilize a global recycle valve to return flow from the discharge side of a centrifugal compressor to the suction side to increase the flow through the compressor and, thus, avoid entering the surge region. This is conventionally handled by defining a compressor surge control line that conservatively assumes that all stages must be kept out of surge at all the time. In compressors with multiple stages, the amount of energy loss is disproportion-ally large since the energy that was added in each stage is lost during system level (or global) recycling. This work proposes an internal stage-wise recycling that provides a much more controlled flow recycling to affect only those stages that may be on the verge of surge. The amount of flow needed for such a scheme will be much smaller than highly conservative global recycling approach. Also, the flow does not leave the compressor casing and therefore does not cross the pressure boundary. Compared to global recycling this inherently has less loss depending upon application and specific of control design.

Efficiency of a Multiple Flywheel Recuperation System

1994 ◽  
Vol 116 (1) ◽  
pp. 332-336 ◽  
Author(s):  
P. Marinov ◽  
S. Pavlov ◽  
V. Draganov
Keyword(s):  
Kinetic Energy ◽  
Dynamic Models ◽  
Energy Losses ◽  
Stored Energy ◽  
Conventional Systems

A multiple flywheel has been studied for the purpose of storing and recuperating kinetic energy. The objective of the design of such systems is a maximum storage and recuperation of the stored energy. Dynamic models of the proposed and the conventional systems are compared regarding energy losses. A coefficient of recuperating efficiency is introduced for demonstrating the advantages of the multiple flywheel system.

Full-Scale Demonstration of Surface-Stabilized Fuel Injectors for Sub-Three ppm NOx Emissions

2004 ◽  
Author(s):  
Steven J. Greenberg ◽  
Neil K. McDougald ◽  
Leonel O. Arellano
Keyword(s):  
Pressure Ratio ◽  
Full Scale ◽  
Low Flow ◽  
Stable Operation ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Fuel Injectors ◽  
Air Inlet ◽  
Radial Profiles ◽  
Developed Surface

ALZETA Corporation has developed surface-stabilized fuel injectors for use with lean premixed combustors which provide extended turndown and ultra-low NOx emission performance. These injectors use a patented technique to form interacting high-flow and low-flow flame zones immediately above a selectively-perforated porous metal surface. This allows stable operation at low reaction temperatures. This technology has been given the product name nanoSTAR™. Previous work involved the development of nanoSTAR technology from the proof-of-concept stage to prototype testing. Rig testing of single injectors and of two injectors simulating a sector of an annular combustion liner have been completed for pressure ratios up to 17 and combustion air inlet temperatures up to 700 K (800°F). This paper presents results from the first ever full-scale demonstration of surface-stabilized fuel injectors. An annular combustion liner, fitted with twelve nanoSTAR injectors was successfully tested up to a pressure ratio of 12 and combustion air inlet temperature of 700 K (800°F). NOx emissions were 2 ppm with CO emissions of 3 ppm both corrected to 15% O2. The combustion system exhibited excellent temperature uniformity around the annular combustor outlet with a maximum pattern factor of 0.16 and engine-appropriate radial profiles.

The effect of pre-detached particles on soil erodibilities associated with erosion by rain-impacted flows

Soil Research ◽  
1994 ◽  
Vol 32 (1) ◽  
pp. 127 ◽  
Author(s):  
PIA Kinnell
Keyword(s):  
Kinetic Energy ◽  
Fine Particles ◽  
Low Flow ◽  
Coarse Particles ◽  
Dynamic Nature ◽  
Soil Matrix ◽  
Degree Of Protection ◽  
Runoff Rate ◽  
Erosivity Index ◽  
Underlying Soil

In shallow rain-impacted flows, particles detached from the soil matrix will produce a layer of pre-detached particles on an eroding surface when entrainment by flow is absent. This layer provides a degree of protection to the underlying soil matrix and material from the layer also contributes to the discharge of sediment across the downstream boundary of an eroding area. The development and effects of the layer are dynamic. The layer tends to be more protective at low flow velocities and with coarse particles than at high velocities and with fine particles. The ease by which particles can be detached from the soil matrix also influences the development of the layer. The dynamic nature of the layer results in the susceptibility of a surface to erosion by rain-impacted flow varying in time and space. The consequence of this is examined with respect to erodibilities associated with an erosivity index that is based on the product of runoff rate and the rate of expenditure of rainfall kinetic energy.

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