Sanden international, an automobile air conditioning compressor manufacturer, was facing a problem in its incoming material inspection procedures. Although the company had designed and was using its own sampling plan, some managers and supervisors where not confident of its reliability. Sanden recently established a goal for its total number of defects per supplier as one part per million. Achievement of this target required reviews of the existing sampling plan. The purpose of this project was to help Sandra identify the best alternatives for its incoming material inspection procedures. To do that considerations were made about the usefulness of sampling inspections, theoretical aspects of inspection sampling plans were examined, current sampling plans were analyzed and recommendations were made.

Orientador: Jorge Isaias Llagostera Beltran / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-08T17:53:07Z (GMT). No. of bitstreams: 1 Lopes_FernandodeOliveira_M.pdf: 4254683 bytes, checksum: 3714a253c99b8967319409a00b69058a (MD5) Previous issue date: 2007 / Resumo: Este trabalho apresenta o desenvolvimento de um programa computacional para modelagem inicial de compressores axiais de vários estágios pertencentes ao conjunto de turbinas a gás. O desenvolvimento do programa se baseia na metodologia adotada por Saravanamutto et al. (2001), faz uso da Primeira Lei da Termodinâmica para cálculo de potência consumida pelo compressor e da Segunda Lei da Termodinâmica para determinar o grau de irreversibilidade do sistema. O programa calcula a quantidade de estágios necessária para uma dada relação de pressão, a quantidade de palhetas por estágio e outros dados construtivos do compressor. O trabalho analisa a eficiência global de uma turbina a gás, avalia rendimento utilizando diferentes tipos combustíveis, estuda a influência da temperatura de entrada do ar no compressor, temperatura de entrada dos gases na turbina, e eficiência isentrópica do compressor e da turbina. Fatores que geram instabilidade no compressor são discutidos e algumas sugestões são apresentadas para evitar que compressores operem fora das condições iniciais. O trabalho apresenta procedimentos claros e detalhados para o préprojeto de um compressor de fluxo axial. Finalmente, o trabalho apresenta uma breve discussão sobre eficiência exergética de máquinas térmicas / Abstract: This work presents the developing of a computational program for designing axial compressors that hold multistage belonged gas turbine. The developing of the program is based on methodology adopted by Saravanamutto et al.(2001), it makes use of the First Law of Thermodynamic to calculate the power required by the axial compressor e the Second Law to calculate the level of irreversibilities. Beside of this the program presents the numbers of stages required for a given pressure ratio, the amount of blades per stage and other building parameters has been included to make a better analyze about the equipment. The work contains thermal efficiency analyzes of a gas turbines, where parameters such as fuels, temperature intlet turbine, environmental conditions, efficiency of the compressor and turbine are included. Other factors such as unstable conditions are discussed and solutions to avoid that axial compressors running in off design conditions. In summary the work provides a global view about thermal machines and how their parameters can influence both in the thermal and exergetic efficiency / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

Flow visualization movies of flow through a cascade of compressor blades showed propagating stall at stagger angles of 36.5 and 45 degrees for angles of attack of 20 degrees and higher. At a stagger angle of 25 degrees, the development of a steady, separated boundary layer occurred with no propagation. The observed propagating stall process was the development of a vortex in the boundary layer and its subsequent shedding. The shedding mechanism was observed to be the interference by the reverse flow from the previously stalled passage with the vortex flow in the stalled passage. This dissipated the vortex in the blade passage and the incoming flow then flushed the stagnated vortex out of the passage. Measurements of propagation speeds showed that the propagation speed is related to the blockage of the passage, that stagger angle has an insignificant effect on propagation speed, and that propagation speed is proportional to the relative velocity. Based on the observations, a geometric model was developed to predict the onset of propagating stall. This model showed that increased solidity, decreased stagger angles, and operation at low angles of attack make a cascade more resistant to propagating stall inception. The model shows the relation of the operating point of a compressor to the stall inception point. When expanded to include all significant aspects of blade geometry, the model may provide a basis for controlling propagating, and hence, rotating, stall inception based on the blade row·geometry. / Master of Science

Pressure signals were taken on a rotor blade surface of a single-stage, low-speed axial flow compressor. The data showed unsteady, stationary pressure perturbations that correlated with the locations of five large downstream support struts. In the present work, these data are thoroughly analysed. Strut-induced pressure amplitudes as measured on the rotor are presented as a function of the downstream strut locations. Unsteady lift and moment are calculated by integrating the pressures measured by the blade-mounted transducers. In addition, a sequence of instantaneous pressure distributions on the blade surfaces presented over time shows how the rotor is influenced by the potential effect of the struts. The strut is shown to produce a significant effect on rotor flow. This effect exceeds the unsteady stator effect at design rotor-stator-strut spacing, but falls off rapidly as the struts are moved downstream. / M.S.

Three models that predict the performance of an oil-flooded single-screw refrigerant compressor are presented. The thermodynamic equations which are a basis for all the models are derived using a control volume approach. The mechanisms for power input to the oil are presented and three of these mechanisms, oil shear, oil displacement, and external oil pumping, are dealt with analytically. The computer model, the most comprehensive model developed, gave detailed thermodynamic information about the internal processes. For the example presented, the powers calculated included (1) the shaft power (99.9 kw), (2) the preheat power (14.8 kw), (3) the closed compression power (85.1 kw), (4) the oil shear power (8.1 kw), (5) the oil displacement power (4.3 kw) and (6) the external oil pumping power (0.85 kw). For this case, the model also predicted the contributions to volumetric inefficiency (8.7%) from preheat (3.75%), recirculating oil (3 .3%) and refrigerant leakage (1.65%). It also gave the overall compression efficiency (71.5%) and the closed compression efficiency (87 .4%) along with the internal pressures, temperatures, and oil flow rates during the compression process. The star tooth tip leakage path was the site of the most oil leakage contributing 2.6% to the volumetric inefficiency. The preheat phenomenon gave rise to extra power consumption during the closed compression process (1/2% increase in ideal compression power for each 1°C additional preheat). The eight variables necessary to define the geometry of a single screw mechanism are given along Awith two techniques to determine the pocket volume and the main rotor shear area. / M. S.

The purpose of this research was to determine if installing a smaller air compressor could reduce the electrical usage of a large semiconductor manufacturing plant. A 200 horsepower Atlas Copco compressor was installed with the existing 500 horsepower Ingersoll-Rand compressors. Testing was conducted during the regular manufacturing process at MEMC Southwest in Sherman, Texas. Analysis of the data found that installing the new compressor could reduce electrical consumption. The study also found there are specific operational setpoints that allow the compressor to operate more efficiently.

Approved for public release; distribution is unlimited / A computational fluid dynamic (CFD) investigation is presented that provides predictions of the aerodynamic impact of uniform and non-uniform coatings applied to the leading edge of a compressor airfoil in a cascade. Using a NACA 65(12)10 airfoil, coating profiles of varying leading edge non-uniformity were added. This non-uniformity is typical of that expected due to fluid being drawn away from the leading edge during the coating process. The CFD code, RVCQ3D, is a steady, quasi-three-dimensional Reynolds Averaged Navier-Stokes (RANS) solver. A k-omega turbulence model was used for the Reynolds' Stress closure. The code predicted that these changes in leading edge shape can lead to alternating pressure gradients in the first few percent of chord that create small separation bubbles and possibly early transition to turbulence. The change in total pressure loss and trailing edge deviation are presented as a function of the coating non-uniformity parameter. Results are presented for six leading edge profiles over a range of incidences and inlet Mach numbers from 0.6 to 0.8. Reynolds number was 600,000 and free-stream turbulence was 6%. A two-dimensional map is provided that shows the allowable degree of coating non-uniformity as a function of incidence and inlet Mach number. / Lieutenant Commander, United States Navy

This research tested to see how audio engineers navigate and use compressors differently with alternative designs. A pre-study in the form of a semi-structured interview with a focus group was held to determine a compressor considered having a “good design” and a compressor considered having a “bad design”. An active test was conducted with audio engineer students to investigate if there is any connection between time it takes for an engineer to navigate a compressor depending on its design. The test also investigated patterns in how audio engineers use compressors differently depending on their design, and what makes it easier to navigate and more satisfactory to use. 6 paired T-test were made between different compressor designs and a video and screen capture was annotated to investigate how audio engineers navigated the compressor. The results showed that 2 out of 6 T-tests gave a significant result, meaning that the time it took to navigate some of the compressors against each other were affected by the design of the compressor interface. Results showed that there are many contributing factor towards why a compressors is easier navigate and more satisfactory to use, but with a slight tendency that “parameter controls”, “visual information” and “aesthetically pleasing” are the most important factors. No findings on how engineers might use compressors differently depending on its design were found. Some additional patterns for audio engineers using compressors were found as well.

Este trabalho tem como objetivo propor e avaliar um novo método para controle antissurto de compressores dinâmicos. É sabido que compressores dinâmicos são sujeitos ao fenômeno de surto, o qual pode danificar gravemente os componentes do compressor e provocar distúrbios de produção. O surto pode surgir a partir da ocorrência de distúrbios (por exemplo, fechamento da válvula de descarga do compressor) os quais, sem ação antissurto, fariam com que o ponto de operação se deslocasse para uma região de baixas vazões delimitada por uma linha conhecida como linha de surto. Portanto, compressores dinâmicos sempre são equipados com mecanismos antissurto: tipicamente uma válvula de reciclo de ação rápida controlada por um controlador PI antissurto. Dado que o surto se desenvolve extremamente rápido, usualmente não se permite que o compressor opere muito próximo da linha de surto. Esse objetivo de controle (manter o compressor afastado da linha de surto) é conflitante com objetivos de eficiência energética, pois os pontos de maior eficiência estão localizados próximos a essa linha. Logo, é desejável operar o compressor utilizando a mínima margem de surto que ainda garanta que a ação antissurto seja efetiva. Este trabalho propõe um método para ativação da ação antissurto no compressor com o objetivo de atingir uma ação mais rápida que o controle PI tradicional. O método proposto se baseia no cálculo offline das aberturas necessárias para a válvula de reciclo para cada possível combinação das posições dos atuadores do sistema, considerando um conjunto discreto pré-definido de valores dentro da faixa de valores de cada atuador. Esse processo gera uma tabela auxiliar para uso online. Os valores da tabela auxiliar são utilizados para gerar valores de referência para um controlador por realimentação, o qual é responsável por garantir que a trajetória do sistema irá do estado inicial no momento da ativação do controle antissurto para o estado estacionário desejado. Diversos cenários de distúrbio são simulados para diferentes controladores por realimentação e comparados com o controle antissurto PI tradicional. Os resultados mostram que a estratégia proposta é um candidato para melhorias na prática atual de controle antissurto, mas um controle por realimentação adequado deve ser selecionado e avaliado também considerando o aspecto de robustez, o qual é brevemente considerado no escopo deste trabalho. / This work aims at proposing and evaluating a novel method for anti-surge control of dynamic compressors. Dynamic compressors are known to suffer from surge, which can severely damage compressor components and disturb production. Surge may arise by the occurrence of disturbances (e.g. compressor discharge valve closure) that would bring its operating point to a region at low flows delimited by the so called surge line. Therefore, dynamic compressors are always equipped with anti-surge mechanisms: typically a fast actuating recycle valve controlled by a PI anti-surge controller. Since surge develops extremely fast, the compressor is usually not allowed to operate too close from the surge line. This control objective (keep the compressor away from the surge line) is conflicting with energy efficiency requirements, since higher efficiency operating points are located close to the surge line. Therefore, it is desirable to operate the compressor using the smallest possible surge margin that still guarantees anti-surge action is effective. This work proposes a method for triggering the compressor anti-surge action, aiming at a faster action than traditional PI control. The proposed anti-surge control method relies on an offline computation of necessary recycle valve openings for each possible combination of the system actuators positions, considering a predefined discrete set of values from the actuators positioning ranges. This generates a look-up table for online use. The values from the look-up table are used to identify the necessary compressor flow set-point for a feedback controller, which is responsible for ensuring that the system trajectory goes from the state upon anti-surge activation to the desired steady state. Several disturbance scenarios are simulated for different feedback controllers and compared to the traditional PI anti-surge controller. Results show that the proposed strategy is a candidate for improvements in current anti-surge control practice but an adequate feedback control strategy must be chosen and evaluated also under the consideration of robustness, which is slightly considered in the scope of this work.

INTRODUÇÃO: O tratamento da fibrose cística (FC) envolve o uso de medicamentos fornecidos através de nebulizadores e seu funcionamento adequado é essencial. OBJETIVOS: Avaliar o desempenho de nebulizadores a jato utilizados por pacientes com FC e comparar dois manômetros para avaliação dos compressores. MÉTODOS: Estudo descritivo, transversal, de avaliação dos nebulizadores usados pelos pacientes com FC da Associação Mineira de Assistência a Mucoviscidose. Os pacientes trouxeram compressores (Proneb Ultra®) e nebulizadores (Pari LC plus®) para avaliação. O desempenho do compressor foi avaliado por medidas de pressão operacional através dos manômetros PARI PG101® (PARI GmbH, Starnberg, Alemanha) e FSA analógico (Famabras, Itaquaquecetuba, Brasil).As variáveis de eficiência do nebulizador foram: O débito de volume nebulizado (DVN), taxa de oferta da medicação (TOR) e volume residual (VR) foram calculados por diferenças de peso de cada nebulizador após 10 minutos de nebulização de solução salina (2,5ml). O diâmetro médio de massa da partícula (DMM) foi calculado através da equação proposta por Standaert et al. A análise estatística incluiu o pacote R (v.2.15) e MINITAB, com alfa=0,05. O coeficiente Kappa foi calculado para avaliar concordância de valores entre os equipamentos, e curva ROC construída para calcular o valor aferido no manômetro FSA com melhor sensibilidade/especificidade, utilizando o manômetro PARI PG101® como referência. A associação entre valores de pressão, DVN, TOR e VR foi calculada pela correlação de Spearman. RESULTADOS: Avaliados 146 sistemas com tempo mediano de uso de 32(12-60) meses±36 meses. Cinquenta e sete (39%) não funcionaram adequadamente, com valores pressóricos inferiores à metade da referência. Os sistemas com funcionamento inadequado comprometeram as variáveis de eficiência dos nebulizadores A concordância entre os diferentes métodos de avaliação de acordo com a classificação; com funcionamento adequado e inadequado através do coeficiente Kappa foi 0,81(IC95%- 0,65-0,97), p<0,001. Na avaliação da sensibilidade e especificidade foi observado o ponto de corte de 23,5 PSI no manômetro FSA mostrou sensibilidade=99% e especificidade=79% (p<0,001). Houve associação significativa entre DVN, VR e pressões aferidas. CONCLUSÕES: Uma proporção significativa dos sistemas de nebulização não funcionou adequadamente. As variáveis de eficiência da nebulização estavam comprometidas indicando que a pressão gerada no compressor é um aspecto crítico na eficiência do tratamento. O método alternativo da avaliação dos compressores se apresentou adequado para ser utilizado nos compressores utilizados no tratamento da FC. / INTRODUCTION: Cystic fibrosis (CF) treatment of involves the use of medications supplied through nebulizers and their proper functioning is essential. OBJECTIVES: To evaluate the performance of jet nebulizers used by CF patients and to compare two pressure gauges Compressors evaluation. METHODS: This was a descriptive, cross - sectional study of the nebulizers used by patients with CF of the Mucoviscidosis Care Association of Minas Gerais. The patients brought compressors (Proneb Ultra®) and nebulizers (Pari LC plus®) for evaluation. The performance of the compressor was evaluated by operating pressure measurements using PARI PG101® manometers (PARI GmbH, Starnberg, Germany) and analog FSA (Famabras, Itaquaquecetuba, Brazil). The variables of efficiency of nebulization under study were: nebulizer delivery volume (NDV), drug output rate (DOR), and residual volume (RV), which were calculated by weighing each nebulizer before nebulization and 10 minutes after nebulization using a saline solution (2.5 mL). The mass median diameter (MMD) was calculated using the equation proposed by Standaert et al. Statistical analysis included the package R (v.2.15) and MINITAB, with alpha = 0.05. The Kappa coefficient was calculated to evaluate agreement of values between the equipment\'s, and ROC curve constructed to calculate the value measured in the FSA manometer with better sensitivity / specificity, using the PARI PG101® manometer as reference. The association between pressure values, NDV, DOR and RV was calculated by the Spearman correlation. RESULTS: We evaluated 146 systems with a median time of use of 32 (12-60) months ± 36 months. Fifty-seven (39%) did not function properly, with pressure values lower than half the reference. The systems with inadequate functioning compromised the efficiency variables of the nebulizers. The agreement between the different evaluation methods according to the classification; with adequate and inadequate functioning through the Kappa coefficient was 0.81 (95% CI -0.65-0.97), p <0.001. In the evaluation of sensitivity and specificity, the cut-off point of 23.5 PSI on the FSA manometer showed sensitivity = 99% and specificity = 79% (p <0.001). There was a significant association between NDV, DOR, RV and measured pressures. CONCLUSIONS: A significant number of the nebulizer systems were ineffective. The variables of nebulization efficiency were compromised, which indicated that the pressure generated by the compressor was a critical aspect for treatment efficiency. The alternative method of compressors evaluation was suitable for use in CF treatment routine.