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Comportamiento termodinámico de rotores para compresores de tornillo con nuevo perfil.
A. Rivera Torres,J. Martínez Escanaverino
Revista de Ingeniería Mecánica , 2007,
Abstract: En el presente artículo se evalúa el comportamiento termodinámico de rotores para compresores de tornillo con nuevos perfiles, realizado con ayuda del software Scorpath 2000. Ello permite predecir con precisión el desempe o completo del compresor y su evaluación termodinámica, así como realizar comparaciones, en igualdad de condiciones, con el trabajo de otros compresores dotados de perfiles de otros tipos.The article displays an evaluation of the thermodynamic behaviour of screw compressor rotors with new profiles, obtained with the help of the Scorpath 2000 software. This allows predicting precisely the operation of the compressor, as well as its thermodynamic evaluation, under equal conditions, with the work of other compressors fitted with rotor profiles of other kinds.
DESARROLLO DE UN INSTRUMENTO VIRTUAL PARA EL BALANCEAMIENTO DINAMICO DE ROTORES DEVELOPMENT OF A VIRTUAL INSTRUMENT FOR ROTOR DYNAMICS BALANCING  [cached]
Edgar Estupi?án P,César San Martin,Luis Canales M
Ingeniare : Revista Chilena de Ingeniería , 2006,
Abstract: El presente trabajo resalta la importancia del balanceamiento de rotores como principal herramienta dentro de las tareas correctivas del mantenimiento predictivo, con el fin de que se reduzcan las vibraciones y sus efectos secundarios en las máquinas rotatorias. Se ha desarrollado un instrumento virtual para el balanceamiento dinámico de rotores, basado en un sistema de adquisición de datos (SAD). El instrumento tiene incluidos todos los cálculos necesarios para balancear rotores en un plano y en dos planos, a partir de la medición de los datos de vibración, utilizando el procedimiento de los coeficientes de influencia o utilizando un procedimiento de medición sin fase. También se ha incluido un módulo para determinar la severidad vibratoria del rotor y un módulo de análisis de vibraciones, que incluye análisis espectral y de la forma de onda. Este instrumento virtual es una herramienta útil para el balanceamiento de rotores en laboratorio así como también en la industria. This article highlights the importance of rotor balancing like the most important corrective action included in a predictive maintenance program, whose main objective is reducing the vibrations level and its secondary effect in rotary machines. A virtual instrument, based in a data acquisition system has been developed for rotor balancing. With this instrument it is possible to balance rotors in a single or two-plane, using the influence coefficient method or a no phase method. Also the instrument includes a function to determine the vibration severity and a function of vibration analysis with spectral and waveform analysis included. This virtual instrument is useful for rotor balancing in the laboratory as well as in the industry.
Reparación por soldadura de rotores de turbinas de vapor y de gas fabricados con aceros al Cr-Mo-V  [cached]
Mazur, Z.,Kubiak, J.,Hernández, A.
Revista de Metalurgia , 1999,
Abstract: An analysis of typical steam turbine and gas turbine rotor failures is carried out. On the base of the rotors different failure causes and their mode of occurring, an evaluation of the weldability of the Cr-Mo-V steels and the classification of the common turbine rotors repair possibilities is presented. The developing of specific in-situ welding repair process of the damaged 20.65 MW gas turbine rotor is described. After repair, the rotor was put back into service. Se presenta un análisis de da os típicos en rotores de turbinas de vapor y de gas fabricados con aceros de baja aleación al Cr-Mo-V. Partiendo de las causas y modos de presentación de los fallos y el deterioro del material de los rotores durante la operación de la turbina, se lleva a cabo un análisis de la soldabilidad de los aceros al Cr-Mo-V y se presenta una clasificación de los posibles tipos de reparaciones de los rotores de turbinas. Con base en los da os presentados en el rotor de la turbina de gas de 20,65 MW, se presenta el desarrollo de la tecnología de reparación por soldadura llevada a cabo in situ. El rotor fue puesto nuevamente en servicio después del proceso de reparación.
Signature of rotors  [PDF]
Mieczyslaw K. Dabkowski,Makiko Ishiwata,Jozef H. Przytycki,Akira Yasuhara
Mathematics , 2004,
Abstract: Rotors were introduced in Graph Theory by W.Tutte. The concept was adapted to Knot Theory as a generalization of mutation by Anstee, Przytycki and Rolfsen in 1987. In this paper we show that Tristram-Levine signature is preserved by orientation-preserving rotations. Moreover, we show that any link invariant obtained from the characteristic polynomial of Goeritz matrix, including Murasugi signature, is not changed by rotations. In 2001, P. Traczyk showed that the Conway polynomials of any pair of orientation-preserving rotants coincide. But it was still an open problem if an orientation-reversing rotation preserves Conway polynomial. We show that there is a pair of orientation-reversing rotants with different Conway polynomials. This provides a negative solution to the problem.
Design and Analysis of Low Power Compressors  [PDF]
S.KARTHICK,S.KARTHIKA,S.VALARMATHY
International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering , 2013,
Abstract: The power management has become a great concern due to the increased usage of multimedia devices.Multipliers are the main sources of power consumption in these devices. The 3-2, 4-2 and 5-2 compressors are the basiccomponents in many applications like partial product summation in multipliers. In this paper, various types ofcompressors have been designed. Different logic styles of XOR-XNOR gates and multiplexers have been compared withthe existing CMOS logic. The pass transistor implementation of XOR-XNOR gates and multiplexer circuits achieves lowpower with less number of transistor counts. The proposed compressor architecture can be built using variouscombinations of XOR-XNOR gates, transistor level implementation and multiplexer circuits. The performance of basiccompressor architectures with these low power XOR-XNOR gates and MUX blocks is found to be efficient in terms ofarea and power. Hence, the proposed 8x8-bit Wallace tree multiplier was designed using this proposed compressors andthe power results are compared with the conventional Wallace tree multiplier design. The proposed Wallace treemultiplier using these compressors achieves significant amount of less power than conventional Wallace tree multiplier.The designs are implemented and power results are obtained using TANNER EDA 12.0 v tool.
Dynamics and interactions of active rotors  [PDF]
M. Leoni,T. B. Liverpool
Physics , 2010, DOI: 10.1209/0295-5075/92/64004
Abstract: We consider a simple model of an internally driven self-rotating object; a rotor, confined to two dimensions by a thin film of low Reynolds number fluid. We undertake a detailed study of the hydrodynamic interactions between a pair of rotors and find that their effect on the resulting dynamics is a combination of fast and slow motions. We analyse the slow dynamics using an averaging procedure to take account of the fast degrees of freedom. Analytical results are compared with numerical simulations. Hydrodynamic interactions mean that while isolated rotors do not translate, bringing together a pair of rotors leads to motion of their centres. Two rotors spinning in the same sense rotate with an approximately constant angular velocity around each other, while two rotors of opposite sense, both translate with the same constant velocity, which depends on the separation of the pair. As a result a pair of counter-rotating rotors are a promising model for controlled self-propulsion.
Compound fuzzy model for thermal performance of refrigeration compressors
Guoliang Ding,Chunlu Zhang,Tao Zhan,Hao Li
Chinese Science Bulletin , 2000, DOI: 10.1007/BF03182912
Abstract: The fuzzy method is introduced to the calculation of thermal performance of refrigeration compressors. A compound model combining classical thermodynamic theory and fuzzy theory is presented and compared with a simple fuzzy model without classical thermodynamic fundamentals. Case study of refrigeration compressors shows that the compound fuzzy model and the simple fuzzy model are both more efficient than the classical thermodynamic method. However, the compound fuzzy model is of better precision and adaptability.
Orienting coupled quantum rotors by ultrashort laser pulses  [PDF]
Hiroyuki Shima,Tsuneyoshi Nakayama
Physics , 2004, DOI: 10.1103/PhysRevA.70.013401
Abstract: We point out that the non-adiabatic orientation of quantum rotors, produced by ultrashort laser pulses, is remarkably enhanced by introducing dipolar interaction between the rotors. This enhanced orientation of quantum rotors is in contrast with the behavior of classical paired rotors, in which dipolar interactions prevent the orientation of the rotors. We demonstrate also that a specially designed sequence of pulses can most efficiently enhances the orientation of quantum paired rotors.
Cooperative Self-Propulsion of Active and Passive Rotors  [PDF]
Yaouen Fily,Aparna Baskaran,M. Cristina Marchetti
Physics , 2011, DOI: 10.1039/C2SM06952K
Abstract: Using minimal models for low Reynolds number passive and active rotors in a fluid, we characterize the hydrodynamic interactions among rotors and the resulting dynamics of a pair of interacting rotors. This allows us to treat in a common framework passive or externally driven rotors, such as magnetic colloids driven by a rotating magnetic field, and active or internally driven rotors, such as sperm cells confined at boundaries. The hydrodynamic interaction of passive rotors is known to contain an azimuthal component \sim 1/r^2 to dipolar order that can yield the recently discovered "cooperative self-propulsion" of a pair of rotors of opposite vorticity. While this interaction is identically zero for active rotors as a consequence of torque balance, we show that a \sim 1/r^4 azimuthal component of the interaction arises in active systems to octupolar order. Cooperative self-propulsion, although weaker, can therefore also occur for pairs of active rotors.
ANáLISIS EXPERIMENTAL Y MODELADO DE COMPRESORES A ESPIRAL EN APLICACIONES HVAC/R  [cached]
CRISTIAN CUEVAS,VINCENT LEMORT,NéSTOR FONSECA DIAZ
Scientia Et Technica , 2010,
Abstract: Este artículo presenta los resultados de un estudio experimental de compresores a espiral. Se analizan los órdenes de magnitud de las eficiencias isentrópicas y volumétricas de estos compresores. Para el modelado se utiliza una aproximación semi-empírica, en donde se identifican algunos parámetros del modelo a partir de mediciones en laboratorio o de catálogos. Se dan algunos ejemplos de identificación de parámetros y de simulación. El modelado pone en evidencia la importancia de considerar los fenómenos físicos que suceden al interior de la máquina para representar de mejor forma su comportamiento. El modelo presentado es de tipo modular por lo tanto puede ser usado luego en un sistema aún más complejo: como es el caso de una bomba de calor, un sistema de refrigeración o de acondicionamiento de aire.
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