Numerical modeling of the performance of a centrifugal compressor impeller with low inlet flow coefficient

The paper presents the results of computational fluid dynamics modeling of the performance of two centrifugal impellers with low inlet flow coefficients. The first impeller with the flow coefficient of 0.024 had nine main and nine splitter blades and the outlet diameter of 447 mm. The second one differed from the first one only by the lack of the splitters, 18 main blades were used instead. The numerical simulations were verified by the experimental measurements performed on a corresponding test rig. The measurements show better performance characteristics of the impeller with splitters. The main aim of the numerical research, therefore, was to identify the reasons for the existing differences in the performance of the impellers

Selected metrological aspects of the compressor initial test operation

W artykule poruszono, opierając się na rzeczywistym przypadku, problematykę przeprowadzania w warunkach przemysłowych ruchów testowych sprężarek i dmuchaw przepływowych. Pokazano typowe trudności dokonywania pomiarów związane ze skalą obiektu i ograniczeniami przestrzennymi. Podano podstawowe wymagania, co do lokalizacji przyrządów pomiarowych, opierając się na obowiązujących normach. Opisano zastosowany układ pomiaru przepływu oraz sformułowano wytyczne metodyki ruchu testowego.The paper discusses problems of initial test operation of blowers under industrial conditions, basing on the existing case. There are shown typical difficulties in taking measurements connected with the object scale and its spatial limitations. The basic requirements for localization of the measurement equipment, complying with the standards in force, are given. A flow measurement system and rules for measuring the initial operating are presented. The paper is an attempt to summarize perennial experience of the Institute of Turbomachinery Tool of the Technical University of Lodz in measurement systems for compressors and blowers. A special attention is paid to the reliability of flow measurements since this problem has been extremely difficult for many years. These difficulties are connected with a very long measurement time and bad condition of measuring instrumentation caused by wear and tear

Projekt oraz numeryczna i eksperymentalna weryfikacja dmuchawy recyrkulacyjnej do długotrwałych testów przepływomierzy turbinowych

A design of the centrifugal recirculation blower as well as results of its experimental and numerical investigations are presented in this paper. The blower was designed to work in the unique test stand which is used for long-term tests of turbine flowmeters. A 1D method was used to design this blower, then experimental and numerical studies were conducted in order to verify the 1D method. A comparison of the blower pressure increase obtained from the experiment and the computations is presented. Velocity and pressure distributions from the numerical simulations in selected sections are also shown and discussed. Additional numerical studies of a shrouded rotor and a rotor with a lower tip clearance were conducted and are presented in the paper as well.W artykule przedstawiono konstrukcje odśrodkowej dmuchawy recyrkulacyjnej oraz wyniki jej badan eksperymentalnych jak i numerycznych. Zaprezentowana dmuchawa została zaprojektowana do pracy na unikalnym stanowisku badawczym, które służy do długoterminowych testów przepływomierzy turbinowych. W artykule zaprezentowano porównanie przyrostu ciśnienia uzyskane z pomiarów i z symulacji numerycznych. Pokazano również rozkłady ciśnień i prędkości dla wybranych powierzchni kontrolnych

Numerical study of surge predecessors in centrifugal blower — inlet recirculation

Paper presents the numerical investigation of inlet recirculation in a centrifugal blower. This phenomenon is known as a local flow instability that is not too harmful in centrifugal compressors compared to centrifugal pumps. However recent findings have shown that it can be regarded as a surge predecessor, and hence very significant for compressors. Therefore there is strong need to understand its physics. One of ways to understand it to apply computational fluid dynamic (CFD) simulations. Therefore in this study the transient numerical simulations were conducted and results were related to the experimental data presented in other papers. Simulation confirmed that the inlet recirculation structure can be resolved by means of CFD and the results are in agreement with some available models. Inlet recirculation structure built up gradually along the circumference increasing the power loss. Obtained structure also explained pressure variations observed in experiments. This has shown that CFD can bring significant improvement in existing antisurge systems and recirculation bleeds that extend the machine operating range

Modernization of a high pressure synthesis gas turbocompressor

The paper describes several modernization aspects of a three-staged synthesis gas radial turbo compressor. The principal aim was to adapt the machine to new working conditions, resulting from the current state-of-art production technology. The required discharge pressure was changed from 21.1 MPa to 14 MPa. The paper covers the discussion on the scope of modernization, its variants and the final variant choice. It provides review of the thermodynamic calculation methodology, dedicated test stand results and also some of the on-site acceptance tests. The revamped compressor is in continuous service since October 2015

Radial fan controlled with impeller movable blades – CFD investigations

Modern classical power generation systems, based on power plants in Poland, where coal (hard bituminous coal or lignite) is the primary energy source, operate under variable loading conditions. Thus, all machines working in the technological system of the power generation unit are required to be adapted to variable loading, and, consequently, to operate beyond the design point of their performance characteristics. High efficiency of the process requires the efficiency of individual devices to be high, beyond the design point, as well. For both air and exhaust gases fans, an effective control system is needed to attain a high level of efficiency. As a result of cooperation between two institutes from the Faculty of Mechanical Engineering, Lodz University of Technology, and the Vibroson company, a new design of the radial fan with impeller movable blades, which allows for controlling the device operation within a wide range, has been developed. This new design and determination the performance characteristics for two geometrical variants of blades with computational fluid dynamics methods are presented. The obtained results have been compared to the results of the measurements of fan performance curves conducted on the test stand