Mass Transfer Modeling into Disk Spaces of Heat Turbomachines

2015 ◽  
Vol 362 ◽  
pp. 1-12
Author(s):  
Nikolay Lazarovski ◽  
Paskal Novakov ◽  
Anastas Yangyozov
Keyword(s):  
Mass Exchange ◽  
Three Dimensional ◽  
Axial Loading ◽  
Steam Turbines ◽  
Labyrinth Seals ◽  
Axial Forces ◽  
Exchange Processes ◽  
Working Medium ◽  
Flow Part ◽  
Mass Transfer Modeling

The thermal aerodynamic analysis of the processes in thermal turbomachinery is of great importance when it comes their design and operation in order to achieve reliable and trouble-free operation in the required turbo-power range. The distribution of kinematic and thermodynamic parameters of the working medium around heavy loaded working disks and labyrinth seals has a significant influence on heat-mass exchange and energy transformation processes. Object of this work is thermo-aerodynamic research of mass exchange processes associated with the movement of the working medium in typical complex clearances between the rotor and stator of the steam turbines of disk type and determining axial forces in the rotor. Results based on one-dimensional and two-dimensional formulations of the problem are analyzed and compared with the results of field experiment of turbine P12-90 / 18, which before the reconstruction had problems with unstable axial loading during operation in wide power range. After proper reconstruction the turbine is in a sustainable balance throughout the whole range of operation modes. There is consistency in the results in quantitative and qualitative terms regarding the extreme conditions of axial loading. There is a three-dimensional approach to solving the problem of distribution of axial loading on the structural elements of the rotor, whose advantage is the obtaining of a detailed picture of the passing fluid in the clearances between the rotor and stator of the aggregate and diaphragm-disk spaces, and a detailed presentation of the uneven distribution of the axial forces on the front surfaces. The applied thermal aerodynamic approach allows to predict the main characteristics of steam turbines at different axial and radial clearances, changing during the operation in case of wear of the the crest of the labyrinth seals. This approach can serve as a thermo-aerodynamic diagnosis of the condition of the flow part of different thermal turbomachinery and in variable working modes.

scholarly journals Heating modes and design optimization of cogeneration steam turbines of powerful units of combined heat and power plant

Energetika ◽  
2019 ◽  
Vol 65 (1) ◽  
Author(s):  
Andrey Rusanov ◽  
Aleksandr Shubenko ◽  
Oleksandr Senetskyi ◽  
Olga Babenko ◽  
Roman Rusanov
Keyword(s):  
Steam Turbine ◽  
Turbulent Flows ◽  
Software Package ◽  
Technical Problem ◽  
Three Dimensional ◽  
Software Systems ◽  
Steam Turbines ◽  
Rational Distribution ◽  
Flow Part ◽  
Numerical Research

An important scientific and technical problem of increasing the efficiency of CHP steam turbine units through the optimization of their operation modes and the creation of new highly efficient flow parts of cogenerating turbines is solved. Solutions to the problem of rational distribution of heat loads between the network heaters of cogeneration turbines during the heating period are presented. The calculations were performed using the software package SCAT which was developed in IPMach NAS of Ukraine. The carrying out of calculations of three-dimensional turbulent flows in flow parts of turbines using modern software systems is an effective direction of increased efficiency of power equipment. For the numerical research of three-dimensional currents, steam in the flow part of the steam turbine software package IPMFlow which is developed in IPMach NAS of Ukraine is used. With the use of software package IPMFlow, the researches of three-dimensional currents steam in the flow part of the medium pressure cylinder of the steam turbine of series T-100-130 are carried, which showed the feasibility of optimizing the geometry of the flow part in order to improve gas-dynamic characteristics of blades apparatuses.

Measurements of Mean Velocity and Mass Exchange in a Separated Recirculating Flow

1975 ◽  
Vol 97 (3) ◽  
pp. 334-341 ◽  
Author(s):  
W. H. Schofield ◽  
T. S. Keeble
Keyword(s):  
Mass Exchange ◽  
Mixing Layer ◽  
Three Dimensional ◽  
Separated Flow ◽  
Momentum Exchange ◽  
Mean Velocity ◽  
Mass Rate ◽  
Recirculating Flow ◽  
Exchange Processes ◽  
Exchange Data

Experimental measurements were taken in a closed, recirculating, turbulent separated flow. The experiments were made to elucidate the mass and momentum exchange mechanisms between the throughflow and the recirculating flow in a combustor that had previously been developed for burning heavy fuels without a flame tube. Mean velocity measurements are presented for the cold flow field and these are used to derive a detailed streamline pattern. The three-dimensional shear layer surface that divides the recirculating flow from the throughflow is analyzed in detail and the variation of momentum exchange coefficient along its development length is derived. Mass exchange data show that the variation of mass transport along the mixing layer is similar to the variation of momentum transport. Overall features of the exchange processes are shown to be similar to those in simple two-dimensional, nonducted mixing flows if allowance is made for the three dimensionality of the present layers. However, it is also shown that there are significant quantitative differences between the two types of flow. The overall mass exchange rate between the two flow regions was found to be one-third of the mass rate supplied to the combustor and this is a typical figure for conventional designs.

Effect of Arch Supports on Ankle—Subtalar Complex Instability: A Biomechanical Experimental Study

2003 ◽  
Vol 24 (8) ◽  
pp. 634-639 ◽  
Author(s):  
Yuki Tochigi
Keyword(s):  
Internal Rotation ◽  
Testing Machine ◽  
Three Dimensional ◽  
Axial Loading ◽  
Management Policy ◽  
Anterior Talofibular Ligament ◽  
Ankle Sprains ◽  
Persistent Symptoms ◽  
Axial Forces ◽  
Arch Support

Background: Subtalar instability, which may cause persistent symptoms after severe inversion ankle sprains, often involves failure of the interosseous talocalcaneal ligament (ITCL). While several clinicians have reported surgical treatment for this pathology, nonsurgical management policy has not been well considered. Previously, it was proposed that ITCL failure possibly causes looseness of the tarsal arch construction resulting in abnormal ankle—subtalar kinematics occurring with axial forces. In the current study the author hypothesized that arch-support insole functions to improve abnormal joint kinematics in ankle—subtalar complex instability. Methods: Five fresh-frozen cadaver lower extremities with simulated ankle—subtalar complex instability, which was created by combined sectioning of the anterior talofibular ligament (ATFL) and the ITCL, were subjected to a biomechanical experiment. Cyclic axial loading from 9.8 to 668 N was applied with a material testing machine, while three-dimensional angular displacements in both the ankle and subtalar joints were determined with electric goniometers. The specimens were tested before and after inserting an arch-support insole that supports the medial-longitudinal and transverse arches of the foot. Results: Inserting the insole decreased the maximum ankle internal rotation, from 3.3° ± 0.9° to 2.3° ± 0.4° ( p = .028), while subtalar rotation was not significantly changed. Conclusions: The medial longitudinal arch-support insole reduced abnormal ankle internal rotation created by combined sectioning of the ATFL and ITCL, likely due to improved arch configuration stability.

scholarly journals Analysis of Turn-to-Turn Fault on Split-Winding Transformer Using Coupled Field-Circuit Approach

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1314
Author(s):  
Cunxiang Yang ◽  
Yiwei Ding ◽  
Hongbo Qiu ◽  
Bin Xiong
Keyword(s):  
Low Voltage ◽  
Short Circuit ◽  
Three Dimensional ◽  
Great Influence ◽  
Normal Operation ◽  
Transient Field ◽  
Axial Forces ◽  
Leakage Field ◽  
Characteristics Analysis ◽  
Split Winding

The turn-to-turn faults (TTF) are also inevitable in split-winding transformers. The distorted leakage field generated by the TTF current results in large axial forces and end thrusts in the fault windings as well as affecting other branch windings normal operation, so it is of significance to study TTF of split-winding transformers. In this paper, the characteristics analysis of the split-winding transformer under the TTFs of the low voltage winding at different positions are presented. A 3600 KVA four split-windings transformer is taken as an example. Then, a simplified three-dimensional simplified model is established, taking into account the forces of the per-turn coil. The nonlinear-transient field-circuit coupled finite element method is used for the model. The leakage field distribution under the TTFs of the low voltage winding at different positions is studied. The resultant force of the short-circuit winding and the force of the per-turn coil are obtained. Subsequently, the force and current relationship between the branch windings are analyzed. The results show that the TTF at the specific location has a great influence on the axial windings on the same core, and the distorted leakage magnetic field will cause excessive axial force and end thrust of the normal and short-circuit windings. These results can provide a basis for the short-circuit design of split-winding transformer.

Influence of a Honeycomb Facing on the Flow Through a Stepped Labyrinth Seal

2000 ◽  
Vol 124 (1) ◽  
pp. 140-146 ◽  
Author(s):  
V. Schramm ◽  
K. Willenborg ◽  
S. Kim ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Theoretical Work ◽  
Labyrinth Seal ◽  
Honeycomb Structure ◽  
Experimental Investigations ◽  
Labyrinth Seals ◽  
Numerical Predictions ◽  
Flow Through ◽  
Aero Engines

This paper reports numerical predictions and measurements of the flow field in a stepped labyrinth seal. The theoretical work and the experimental investigations were successfully combined to gain a comprehensive understanding of the flow patterns existing in such elements. In order to identify the influence of the honeycomb structure, a smooth stator as well as a seal configuration with a honeycomb facing mounted on the stator wall were investigated. The seal geometry is representative of typical three-step labyrinth seals of modern aero engines. The flow field was predicted using a commercial finite volume code with the standard k-ε turbulence model. The computational grid includes the basic seal geometry as well as the three-dimensional honeycomb structures.

Stiffened Hangers: an Often Overlooked Tool for Conceptual Design of Tied-Arch Footbridges

2021 ◽  
Author(s):  
Juan José Jorquera-Lucerga ◽  
Juan Manuel GARCÍA-GUERRERO
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Structural Response ◽  
Bending Moments ◽  
Structural Element ◽  
Axial Forces ◽  
Limited Effectiveness ◽  
Out Of Plane ◽  
Arch Bridges ◽  
Fixed End

<p>In tied-arch bridges, the way the arch and the deck are connected may become crucial. The deck is usually suspended from hangers made out of steel pinned cables capable of resisting axial forces only. However, a proper structural response, (both in-plane and out-of-plane) may be ensured by fixing and stiffening the hangers in order to resist, additionally, shear forces and bending moments. This paper studies the effect of different pinned and stiffened hanger arrangements on the structural behavior of the tied-arch footbridges, with the intention of providing designers with useful tools at the early steps of design. As a major conclusion, regarding the in-plane behavior, hangers composed of cables (either with vertical, Nielsen-Löhse or network arrangements) are recommended due to its low cost and ease of erection. Alternatively, longitudinally stiffened hangers, fixed at both ends, can be used. Regarding the out-of-plane behavior, and in addition to three-dimensional arrangements of cables, of limited effectiveness, transversally stiffened hangers fixed at both ends are the most efficient arrangement. A configuration almost as efficient can be achieved by locating a hinge at the end corresponding to the most flexible structural element (normally the arch). Its efficiency is further improved if the cross-section tapers from the fixed end to the pinned end.</p>

scholarly journals Numerical Analysis on Steam Exciting Force Caused by Rotor Eccentricity

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
L. H. Cao ◽  
J. X. Wang ◽  
P. Li ◽  
P. F. Hu ◽  
Y. Li
Keyword(s):  
Pressure Fluctuation ◽  
Exciting Force ◽  
Width Ratio ◽  
Leakage Flow ◽  
Steam Turbines ◽  
Labyrinth Seals ◽  
Full Circle ◽  
Exciting Vibration ◽  
Numerical Simulator ◽  
Main Factor

The steam exciting force has been proved to be great threat to the operation safety of steam turbines. The mechanism of steam exciting vibration cannot be profoundly revealed by simply analyzing the steam exciting force, especially in simplified models. Therefore, a full-circle stage of steam turbine with shroud and labyrinth seals was investigated by numerical simulator CFX. The instability of leakage flow and the pressure fluctuation were analyzed on the eccentric condition. The effects of leakage vortexes, the depth-width ratio of seal cavity, and the eccentricity on the steam exciting force were studied. Results show that the leakage flow is nonuniform in the circumferential direction with the change of front teeth vortexes, which causes the steam exciting force. The tangential and radial steam exciting force both increase with the eccentricity increasing. The effects of the depth-width ratio of seal cavity on the two forces are different. In addition, the pressure fluctuation caused by the leakage vortexes on the shroud surfaces is a main factor inducing the steam exciting force. This research provides a theoretical guidance for the operation safety and optimization of steam turbines.

scholarly journals Methodology of software development for artificial microclimate control systems

2020 ◽  
pp. 21-31
Author(s):  
Ihor Golinko ◽  
Pavlo Gikalo
Keyword(s):  
Control System ◽  
Software Development ◽  
Control Systems ◽  
Mass Exchange ◽  
Air Conditioning ◽  
Block Diagram ◽  
Dew Point ◽  
Program Logic ◽  
Air Conditioners ◽  
Exchange Processes

The specificity of accelerated software development for microcontrollers is considered. The software development technique for a program-logic controller is presented on the example of an algorithm for controlling the industrial premises microclimate. The method of “dew point” for the control system of industrial air conditioning. The analysis of the functioning of the control system of industrial air conditioning according to the “dew point” method has been carried out and a block diagram of the control system of an artificial microclimate has been proposed. Structurally, the mathematical description of an artificial microclimate system is presented, which takes into account the nonlinearity of mass-exchange processes of air preparation. It can be used by specialists to implement computer-integrated technologies and to analyze and adjust the parameters of the control system of industrial air conditioners.

scholarly journals Universal multifunctional device for heat and mass exchange processes during organic raw material processing

2018 ◽  
Vol 6 (1 (96)) ◽  
pp. 47-54 ◽  
Author(s):  
Aleksey Zagorulko ◽  
Andrii Zahorulko ◽  
Kateryna Kasabova ◽  
Vitalii Chervonyi ◽  
Oleksandr Omelchenko ◽  
...  
Keyword(s):  
Material Processing ◽  
Mass Exchange ◽  
Raw Material ◽  
Heat And Mass Exchange ◽  
Exchange Processes ◽  
Multifunctional Device

Sequential vs Multidisciplinary Coupled Optimization and Efficient Surrogate Modelling of a Last Stage and the Successive Axial Radial Diffuser in a Low Pressure Steam Turbine

2014 ◽  
Author(s):  
Kevin Cremanns ◽  
Dirk Roos ◽  
Arne Graßmann
Keyword(s):  
Steam Turbine ◽  
Design Process ◽  
Energy Demand ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Low Pressure ◽  
Steam Turbines ◽  
Low Pressure Turbine ◽  
Pressure Steam ◽  
Last Stage

In order to meet the requirements of rising energy demand, one goal in the design process of modern steam turbines is to achieve high efficiencies. A major gain in efficiency is expected from the optimization of the last stage and the subsequent diffuser of a low pressure turbine (LP). The aim of such optimization is to minimize the losses due to separations or inefficient blade or diffuser design. In the usual design process, as is state of the art in the industry, the last stage of the LP and the diffuser is designed and optimized sequentially. The potential physical coupling effects are not considered. Therefore the aim of this paper is to perform both a sequential and coupled optimization of a low pressure steam turbine followed by an axial radial diffuser and subsequently to compare results. In addition to the flow simulation, mechanical and modal analysis is also carried out in order to satisfy the constraints regarding the natural frequencies and stresses. This permits the use of a meta-model, which allows very time efficient three dimensional (3D) calculations to account for all flow field effects.

Sign in / Sign up

Export Citation Format

Share Document