Romanian Research and Development Institute for Gas Turbines COMOTI

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Romanian Research and Development Institute for Gas Turbines COMOTI

Romania
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Olaru D.,Romanian Research and Development Institute for Gas Turbines COMOTI | Cuciumita C.F.,Romanian Research and Development Institute for Gas Turbines COMOTI | Vilag V.A.,Romanian Research and Development Institute for Gas Turbines COMOTI
Energy Procedia | Year: 2017

The present technology in gas turbine engines is to burn fuel in the combustion chamber and occasionally in the postcombustion chamber. Current conventional developments of gas turbine aero-thermodynamics provide small efficiency and power increase, because with the present technology one reached an asymptotical convergence to the upper limit of the gas turbine performance. An interesting and almost unexploited possibility is to continue combustion in the turbine, option that, up until recently, has been considered undesirable for a number of reasons. A turbine-combustor is defined as a turbine in which fuel is injected and combusted. The process of combustion in the turbine is called in situ reheat. Thermodynamic cycle, (a hybrid between the Ericsson and Brayton cycles) analyses have demonstrated the benefits of using reheat in the turbine in order to increase specific power and thermal efficiency. [1] © 2017 The Authors.


Stika L.A.,Romanian Research and Development Institute for Gas Turbines COMOTI | Megherelu G.,Romanian Research and Development Institute for Gas Turbines COMOTI | Vilag V.A.,Romanian Research and Development Institute for Gas Turbines COMOTI
Energy Procedia | Year: 2017

This paper focuses on the numerical study of a shaft's cooling, positioned at the end of the gas turbine hot section. Due to convection and conduction phenomena, the high temperatures of the primary gas flow are transferred -via the power turbine's blades and disk- to the power turbine's shaft. If the values of these transmitted temperatures are too high, in time, negative effects can occur, like: rotor imbalance or overheating the oil surrounding the power turbine's shaft. Therefore, for the turbine's shaft to operate properly, a cooling method must be applied. The cooling method considered in this study, is a secondary air flow path, which crosses through the labyrinth, part of the shaft itself and turbine's disk. In order to investigate the heat transfer between the secondary air flow and the turbine's shaft, several computations were performed, using the CFD software Ansys CFX. Several cases were analyzed, by modifying the geometry, the material, as well as the air mass flow passing through the analyzed path. The comparison between the different results led to the selection of the best configuration, in terms of cooling performances. © 2017 The Authors.


Popovici T.D.,Polytechnic University of Bucharest | Popovici T.D.,Romanian Research and Development Institute for Gas Turbines COMOTI | Dijmarescu M.R.,Romanian Research and Development Institute for Gas Turbines COMOTI
IOP Conference Series: Materials Science and Engineering | Year: 2017

The aim of the research presented in this paper is to determine a cutting force prediction model for milling machining of the X105CrMo17 stainless steel. The analysed material is a martensitic stainless steel which, due to the high Carbon content (∼1%) and Chromium (∼17%), has high hardness and good corrosion resistance characteristics. This material is used for the steel structures parts which are subject of wear in corrosive environments, for making valve seats, bearings, various types of cutters, high hardness bushings, casting shells and nozzles, measuring instruments, etc. The paper is structured into three main parts in accordance to the considered research program; they are preceded by an introduction and followed by relevant conclusions. In the first part, for a more detailed knowledge of the material characteristics, a quality and quantity micro-analysis X-ray and a spectral analysis were performed. The second part presents the physical experiment in terms of input, necessary means, process and registration of the experimental data. In the third part, the experimental data is analysed and the cutting force model is developed in terms of the cutting regime parameters such as cutting speed, feed rate, axial depth and radial depth. © Published under licence by IOP Publishing Ltd.


Popovici T.D.,Polytechnic University of Bucharest | Popovici T.D.,Romanian Research and Development Institute for Gas Turbines COMOTI | Dijmarescu M.R.,Romanian Research and Development Institute for Gas Turbines COMOTI
IOP Conference Series: Materials Science and Engineering | Year: 2017

The aim of the research presented in this paper is to analyse the cutting data influence upon surface quality for 17-4 PH stainless steel milling machining. The cutting regime parameters considered for the experiments were established using cutting regimes from experimental researches or from industrial conditions as basis, within the recommended ranges. The experimental program structure was determined by taking into account compatibility and orthogonality conditions, minimal use of material and labour. The machined surface roughness was determined by measuring the Ra roughness parameter, followed by surface profile registration in the form of graphics which were saved on a computer with MarSurf PS1Explorer software. Based on Ra roughness parameter, maximum values were extracted from these graphics and the influence charts of the cutting regime parameters upon surface roughness were traced using Microsoft Excel software. After a thorough analysis of the resulting data, relevant conclusions were drawn, presenting the interdependence between the surface roughness of the machined 17-4 PH samples and the cutting data variation. © Published under licence by IOP Publishing Ltd.


Gherman B.G.,Romanian Research and Development Institute for Gas Turbines COMOTI | Malael I.,Romanian Research and Development Institute for Gas Turbines COMOTI | Mihaescu M.,KTH Royal Institute of Technology | Porumbel I.,Romanian Research and Development Institute for Gas Turbines COMOTI
22nd AIAA Computational Fluid Dynamics Conference | Year: 2015

The paper presents the aerodynamic analysis of an air jet pump by means of Reynolds Averaged Navier-Stokes (RANS) simulations. A baseline configuration, reproducing an existing jet pump is first analysed from the perspective of overall mean compressible flow behaviour, turbulence production and mixing, and efficiency performance. Several constructive solutions are proposed in order to achieve enhanced mixing and efficiency performance. All the cases are investigated for the same operating condition of interest. As a result of the numerical analysis, two solutions are selected as potential improved constructive solutions in terms of mixing and efficiency performance. It is intended to complement the study by further experimental measurements for the baseline set-up and for the two selected configurations, in order to assess their actual performance and to validate the numerical data. © 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.


Petcu A.C.,Romanian Research and Development Institute for Gas Turbines COMOTI | Florean F.G.,Romanian Research and Development Institute for Gas Turbines COMOTI | Porumbel I.,Romanian Research and Development Institute for Gas Turbines COMOTI | Berbente C.,Polytechnic University of Bucharest | Silivestru V.,Romanian Research and Development Institute for Gas Turbines COMOTI
Energy for Sustainable Development | Year: 2016

Camelina is well-suited to be a sustainable biofuel crop, as its seeds naturally have high oil content. The process of obtaining bio-kerosene from camelina oil by hydrotreatment is time-consuming and expensive, thus the possibility of using straight camelina oil/kerosene mixtures as fuel in terrestrial applications is considered. For this purpose, combustion tests were conducted on a burner. Three camelina oil/kerosene mixtures were tested. The influence of the variation of the fuel preheating temperature was also studied and presented. During the tests, the composition of the exhaust gas and its temperature were monitored and registered using two gas analysers. The results were compared with those obtained when the burner was fuelled with pure kerosene. © 2016 International Energy Initiative.


Banu A.,Polytechnic University of Bucharest | Marcu M.,Institute of Physical Chemistry Ilie Murgulescu | Alexandrescu E.,Romanian Research and Development Institute for Gas Turbines COMOTI | Anghel E.M.,Institute of Physical Chemistry Ilie Murgulescu
Journal of Solid State Electrochemistry | Year: 2014

Electrochemical depositions of hybrid polypyrrole/nickel cobalt oxide (PPy/NiCoO) coatings onto ferritic stainless steel surface were carried out with different electrochemical techniques from 0.1 M pyrrole (Py) in 0.2-M oxalic acid (OA) solution and less than 150-nanometer-sized NiCoO particles. The structural properties of the composite were investigated by using different methods such as transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometer (EDS) and Raman spectroscopy. The embedded NiCoO particles, uniformly distributed onto the surface of the PPy film, have similar oxide ratios corresponding to a mixed oxide structure. The electrochemical characterization was done using polarization curves and linear sweep voltammetry (LSV) related to oxygen reduction reaction (ORR) in alkaline solution and hydrogen peroxide as an oxygen source. Concerning the exchange current densities for ORR, the obtained values (between 1.06 and 1.45 × 10−3 mA cm−2 for a total amount of NiCoO of 0.1 mg cm−2) are comparable with other polymer films with Pt. © 2014, Springer-Verlag Berlin Heidelberg.


Petcu A.C.,Romanian Research and Development Institute for Gas Turbines COMOTI | Plesu V.,Polytechnic University of Bucharest | Berbente C.,Polytechnic University of Bucharest
UPB Scientific Bulletin, Series B: Chemistry and Materials Science | Year: 2016

Camelina is one of the most promising sources of renewable fuels. The crude oil obtained from this plant can be chemically treated and converted into bio-diesel or bio-kerosene. To study straight camelina oil combustion process is very important to know as many of its properties as possible. In this article, estimation methods of several thermophysical properties, such as: critical properties, density, thermal conductivity, and specific heat are presented. Where it was possible, the estimated values have been compared with experimental measurements, thus validating the used method.


MAlAel I.,Romanian Research and Development Institute for Gas Turbines COMOTI | DrAgan V.,Romanian Research and Development Institute for Gas Turbines COMOTI | Gherman B.,Romanian Research and Development Institute for Gas Turbines COMOTI
Annals of DAAAM and Proceedings of the International DAAAM Symposium | Year: 2015

In this paper, the authors performed a series of numerical analysis using CFD methods for the study of turbulence intensit effects on the efficiency of a wind turbine vertical axis Darrieus type, at the starting point. These analyzes have the ti speed ratio value (TSR) equal to 1. The solver used is based on pressure and it uses the Simple Method (semi-implicitmethod pressure-linked-equation). To determine the influence of the turbulence intensity were imposed on borde conditions, the intensity values between 1 and 20%. Finally, are represented variations of moment and power coefficient for a full rotation (0-360 degrees). The magnitude vorticity variation is also presented for all the studied cases.


Barbu E.,Romanian Research and Development Institute for Gas Turbines COMOTI | Fetea G.,Romanian Research and Development Institute for Gas Turbines COMOTI | Petcu R.,Romanian Research and Development Institute for Gas Turbines COMOTI | Vilag V.,Romanian Research and Development Institute for Gas Turbines COMOTI | Dragasanu L.,Romanian Research and Development Institute for Gas Turbines COMOTI
Chemical Engineering Transactions | Year: 2013

The new generation of afterburning installations of the cogeneration groups with gas turbine will have to take into consideration the emissions, efficiency and process requirements. The paper presents the research performed at cogeneration power plant 2xST 18 - Suplacu de Barcau, Romania, on afterburning installation flow and NOx emissions, the stage of CFD simulations and test bench experiments. For an integrated analysis of the afterburning installation, at different functional configurations of the cogeneration group, were studied: NOx emission at heat recovery steam generator stack, burning gases temperature at the end of afterburning chamber, infrared image of the upper part of burner. Data analysis, obtained at partial loads allowed obtaining an experimental burner that has 30 % less NOx emissions than the one in the power plant. Experiencing the burner at nominal load, currently mounted on test bench, will permit the validation of numerical model and verification of performances. Copyright © 2013, AIDIC Servizi S.r.l.

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