Papers by Joao marcio Pinto paulon
Volume 1: Turbomachinery, 1982
Experimental investigations brought to light the possibilities of broadening the operating range ... more Experimental investigations brought to light the possibilities of broadening the operating range of axial flow compressors by means of outer wall casing treatments such as grooves, honeycombs or cavities. The industrial use of these techniques is however limited by uncertainties on the effectiveness of these treatments as, while they are very beneficial in some cases, they deteriorate the performance of the machine in some others. A theoretical investigation has been conducted on the flow field in cavities most commonly used, and laws for determining the groove depth have been established which account for the surge margin improvement obtained in some cases and make it possible to dismiss inefficient geometric configurations. A comparison between theory and experiment is presented, based on test results published in the literature and on an experimentation on two industrial compressors.
ASME 1972 International Gas Turbine and Fluids Engineering Conference and Products Show, 1972
A method is presented for experimental data verification on axial supersonic compressors. The act... more A method is presented for experimental data verification on axial supersonic compressors. The actual data are submitted to thoroughly analyzed validity criteria and then accepted, corrected or rejected. An example of experimental results obtained on a rotating supersonic cascade and the final processed data are also shown.
Journal of Engineering for Power, 1970
A single, isolated, test axial compressor rotor in a constant section annular duct is used for de... more A single, isolated, test axial compressor rotor in a constant section annular duct is used for determination of off-design pressure losses. The results obtained are interpreted by means of loss coefficients and description of the flow field is deduced from a simplified actuator theory that takes into account pressure losses. Rotor stall limit is interpreted as that limit mass flow rate for which no continuous solution of the equations can be obtained. Unstable operations that take place for mass flow rates smaller than the stall limit are shown to be either rotating stall or wall separation, according to the shape of the downstream pressure profile. Experiments on the rotor confirm validity of these assumptions.
La Houille Blanche, 1987
Evolution récente de l'appareillage et des techniques de mesures en aérodynamique et en hydrodyna... more Evolution récente de l'appareillage et des techniques de mesures en aérodynamique et en hydrodynamique New developments concerning aerodynamics and hydrodynamics measurement techniques and equipment J. Paulon üNERA Au cours des dernières années, des moyens de mesure nouveaux et très performants ont été développés et mis au point dans divers laboratoires et centres de recherches. Le principe de ces nouveaux moyens est brièvement exposé et des exemples d'application sont donnés, particulièrement dans le domaine de l'aérodynamique ainsi que dans celui de l'hydrodynamique. Ce tour d'horizon, certes incomplet, montre que les chercheurs disposent d'un large éventail de moyens de mesure permettant d'accéder à une connaissance plus fine des phénomènes. In recent years, new and high-performance measurement means have been developed and used in various laboratories and research centres. The principle relating to these new means is briefly described and application examples are given, in particular as regards the aerodynamics and hydrodynamics fields. This innovation shows that the research workers have a wide range of measurement means enabling more precise knowledge of such phenomena to be acquired.
International Journal of Turbo and Jet Engines, 1987
Industrial pumps are generally used in a wide range of operating conditions from almost zero mass... more Industrial pumps are generally used in a wide range of operating conditions from almost zero mass flow to mass flows larger than the design value. It has often been noted that the head-mass flow characteristic, at constant speed, presents a negative bump as the mass flow is somewhat smaller than the design mass flows. Flow and mechanical instabilities appear, which are unsafe for the facility. An experimental study has been undertaken in order to analyze and if possible to palliate these difficulties. A detailed flow analysis has shown strong three-dimensional effects and flow separations. From this better knowledge of the flow field, a particular device was designed and a strong attenuation of the negative bump was obtained. Nomenclature D volume flow rate, m .sec" G gravity constant, 9.81 m.sec" Η total head, m R outer radius, m U peripheral velocity, m.sec" δ flow coefficient μ total head coefficient
Journal of Engineering for Power, 1975
Journal of Engineering for Power, 1975
Results of an experimental research on the comparison of flow patterns in linear and annular, fix... more Results of an experimental research on the comparison of flow patterns in linear and annular, fixed and rotating supersonic blade cascades are presented. The fixed plane cascade and the fixed annular cascade give very similar results at low back pressure and the flow configuration (Schlieren pictures) and the pressure distributions are those given by theoretical calculations. In the rotating cascade the fully started supersonic regime was not obtained. At high back pressure, sidewall flow separation perturbates the flow pattern in the plane cascade. In the annular setups, the flow configuration with suction side flow separation is correctly predicted by the theory.
La Houille Blanche, 1986
Les pompes industrielles sont généralement utilisées dans un large domaine de fonctionnement, dep... more Les pompes industrielles sont généralement utilisées dans un large domaine de fonctionnement, depuis un débit presque nul jusqu'à des débits sensiblement plus élevés que la valeur de projet. Souvent, on a observé que la caractéristique hauteur-débir, à vitesse constante, présenre un « creux» négatif. lorsque le débit devient légèrement inférieur au débit de projet. Des instabilités aérodynamiques et mécaniques apparaissent, qui peuvent être dangereuses pour la machine. Afin d'analyser et, si possible, de pallier ces difficultés, une étude expérimentale a été entreprise conjointement par l'ONERA et Alsthom/Rareau. Une analyse détaillée de l'écoulement a mis en évidence des décollements et d'importants effets tridimensionnels. De cette meilleure connaissance du champ d'écoulement, nous avons pu imaginer un dispositifparticulier qui a permis d'obtenir une très forte atténuation du « creux ». Industrial pumps are generally used in a wide range of operating conditions from zero or almost zero mass jlow to mass jlows lmger than the design value. It has been often noted that the head-mass jlow characteristic of conventional axial jlow pumps operating at constant speed presents a negative hump as the mass jlow becomes somewhat smaller than the design mass jlow. The pump does not stail, there is no reallow frequency oscillations in the circuit, but jlow and mechanical instabilities, unsafe for the facility, are present for sorne intermedimy jlow range. A joint experimen/al ven/ure between ONERA and Alsthom/Ra/eau Division was undertaken in order to analyze and if possible /0 palliate these difficulties. The tests were performed in air instead of water, keeping the same jlow coefficients.
Interaction phenomena between rotor and stator are unavoidable in advanced compressors and their ... more Interaction phenomena between rotor and stator are unavoidable in advanced compressors and their effects increase with the performances of the turbomachines. Until now, it was not possible to quantify the interaction effects, but with the development of 3-D unsteady computation codes in a complete stage, it is possible to know, in detail, the flow field through the machine and to make evident and to explain the difficulties encountered in measuring the flow parameters.
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Papers by Joao marcio Pinto paulon