Performance Of Centrifugal Compressor Research Articles

Ported Shroud 원심압축기 성능에 미치는 운용고도의 영향

Ported Shroud 원심압축기 성능에 미치는 운용고도의 영향

Determination of a suitable set of loss models for centrifugal compressor performance prediction

Performance prediction in preliminary design stages of several turbomachinery components is a critical task in order to bring the design processes of these devices to a successful conclusion. In this paper, a review and analysis of the major loss mechanisms and loss models, used to determine the efficiency of a single stage centrifugal compressor, and a subsequent examination to determine an appropriate loss correlation set for estimating the isentropic efficiency in preliminary design stages of centrifugal compressors, were developed. Several semi-empirical correlations, commonly used to predict the efficiency of centrifugal compressors, were implemented in FORTRAN code and then were compared with experimental results in order to establish a loss correlation set to determine, with good approximation, the isentropic efficiency of single stage compressor. The aim of this study is to provide a suitable loss correlation set for determining the isentropic efficiency of a single stage centrifugal compressor, because, with a large amount of loss mechanisms and correlations available in the literature, it is difficult to ascertain how many and which correlations to employ for the correct prediction of the efficiency in the preliminary stage design of a centrifugal compressor. Asa result of this study, a set of correlations composed by nine loss mechanisms for single stage centrifugal compressors, conformed by a rotor and a diffuser, are specified.

Numerical analysis of flow in a centrifugal compressor with circumferential grooves: influence of groove location and number on flow instability

As an effective and economic method for flow range enhancement, circumferential groove casing treatment (CGCT) is widely used to increase the stall margin of compressors. Different from traditional grooved casing treatments, in which the grooves are always located over the rotor in both axial and radial compressors, one or several circumferential grooves are located along the shroud side of the diffuser passage in this paper. Numerical investigations were conducted to predict the performance of a low flow rate centrifugal compressor with CGCT in diffuser. Computational fluid dynamics (CFD) analysis is performed under stage environment in order to find the optimum location of the circumferential casing groove in consideration of stall margin enhancement and efficiency gain at design point, and the impact of groove number to the effect of this grooved casing treatment configuration in enhancing the stall margin of the compressor stage is studied. The results indicate that the centrifugal compressor with circumferential groove in vaned diffuser can obtain obvious improvement in the stall margin with sacrificing design efficiency a little. Efforts were made to study blade level flow mechanisms to determine how the CGCT impacts the compressor’s stall margin (SM) and performance. The flow structures in the passage, the tip gap, and the grooves as well as their mutual interactions were plotted and analysed.

A network application for modeling a centrifugal compressor performance map

The approximation of aerodynamic performance of a centrifugal compressor stage and vaneless diffuser by neural networks is presented. Advantages, difficulties and specific features of the method are described. An example of a neural network and its structure is shown. The performances in terms of efficiency, pressure ratio and work coefficient of 39 model stages within the range of flow coefficient from 0.01 to 0.08 were modeled with mean squared error 1.5 %. In addition, the loss and friction coefficients of vaneless diffusers of relative widths 0.014-0.10 are modeled with mean squared error 2.45 %.

Effects of Radial Gap Ratio between Impeller and Vaned Diffuser on Performance of Centrifugal Compressors

A high-performance centrifugal compressor is needed for numerous industry applications nowadays. The radial gap ratio between the impeller and the diffuser vanes plays an important role in the improvement of the compressor performance. In this paper, the effects of the radial gap ratio on a high-pressure ratio centrifugal compressor are investigated using numerical simulations. The performance and the flow field are compared for six different radial gap ratios and five rotational speeds. The minimal radial gap ratio was 1.04 and the maximal was 1.14. Results showed that reducing the radial gap ratio decreases the choke mass flow rate. For the tip-speed Mach number (impeller inlet) with Mu < 1, the pressure recovery and the loss coefficients are not sensitive to the radial gap ratio. However, for Mu ≥ 1, the best radial gap ratio is 1.08 for the pressure recovery and the loss coefficients. Furthermore, the impeller pressure ratio and efficiency are reduced by increasing the radial gap ratio. Finally, the compressor efficiency was compared for different radial gap ratios. For Mu < 1, the radial gap ratio does not have noticeable effects. In comparison, the radial gap ratio of 1.08 has the best performance for Mu ≥ 1.

원심압축기 공력성능 해석 프레임워크 구축

A framework for the aerodynamic performance analysis of a centrifugal compressor was constructed using the nondimensional performance. Because of the much time and efforts for the new design of centrifugal compressors, it is widely used in the industry to assess the performance of the compressor under the new operating conditions based on the existing performance results and to apply some design changes to the existing compressors. When checking the performance of centrifugal compressors for different operating conditions by using the existing results, it is easy to utilize the non-dimensional performance head coefficient. If the framework of the non-dimensional performance coefficient is utilized, it is convenient to input design variables and performance curve data. Also it is easy to perform the non-dimensional analysis and performance review for off-design points. The accuracy of the framework was verified by comparison with the results of two 1-stage centrifugal compressors at off-design conditions.

Influence of geometrical modeling on the results of numerical prediction for the centrifugal compressor with shrouded impeller

The overall perfomance of a centrifugal compressor prototype stage with shrouded impeller has been measured. Some factors influencing the numerical prediction accuracy and choke mass flow rate have been investigated numerically using different computational models generated by the component superposition method. A structure correction method using the equivalent blade thickness to replace the impeller fillet was proposed and verified. The main goal of this research was to find out a reasonable simulation strategy for the centrifugal compressor with shrouded impeller through assessing the influence of various fine structures and omitted treatments on the overall performance. A peak isentropic efficiency of 80.28% for the compressor stage was obtained experimently while the numerical model with the equivalent blade thickness correction achieved a peak efficiency of 82.02%. The results indicate that the shroud gap and seal, the impeller fillet as well as the blade machining error are the main geometric structure factors to influence the shrouded centrifugal compressor performance. The shroud gap leakage flow decreases the effective throat area of the shrouded impeller, which leads to the decrease of the choke mass flow rate, the acceleration of the fluid in the impeller passage and the reduce of the impeller diffusion ability. At a given exit pressure, the choke mass flow rate decreases with the increase of the impeller blade relative thickness. Using the equivalent blade thickness to replace the impeller fillet can make the compressor maintain an unchanged performance in the small mass flow conditions , but improve the numerical simulation accuracy in the large mass flow conditions.

Latest technologies and novel approaches in coal seam gas centrifugal compressor trains in Australia

Latest guidelines, novel technical notes, new technical knowledge and recent lessons learned are discussed for emerging market of coal seam gas (CSG) centrifugal compressor trains. Optimum configurations and novel arrangements for coal seam gas (CSG) centrifugal compressor trains driven by gas turbines are addressed. Untreated and saturated nature of CSG need special considerations. Operation, performance, degradation, reliability and maintenance issues of centrifugal compressors, gas turbines, gear units and couplings are also explained. The focus is on new technical knowledge, latest experiences and recent lessons learned on these topics. New recommendations regarding centrifugal compressor train components, gas turbines, machinery arrangement, auxiliaries, gear units, lubrication oil systems, bearings, casing and condition monitoring are also presented. A case study is discussed.

Characterizing Flow Effects of Ported Shroud Casing Treatment on Centrifugal Compressor Performance

This paper presents an investigation of the effects of ported shroud (PS) self-recirculating casing treatment used in turbocharger centrifugal compressors for increasing the operable range. The investigation consists of computing three-dimensional flow in a representative centrifugal compressor with and without PS at various levels of approximations in flow physics and geometrical configuration; this provides an enabler for establishing the causal link between PS flow effects and compressor performance changes. It is shown that the main flow path perceives the PS flow as a combination of flow actuations that include injection and removal of mass flow and injection of axial momentum and tangential momentum. A computational model in which the presence of the PS is replaced by imposed boundary conditions (BCs) that reflect the individual flow actuations has thus been formulated and implemented. The removal of a fraction of the inducer mass flow has been determined to be the dominant flow actuation in setting the performance of PS compressors. Mass flow removal reduces the flow blockage associated with the impeller tip leakage flow and increases the diffusion in the main flow path. Adding swirl to the injected flow in the direction opposite to the wheel rotation results in an increase of the stagnation pressure ratio and a decrease of the efficiency. The loss generation in the flow path has been defined to rationalize efficiency changes associated with PS compressor operation.

NUMERICAL SIMULATION ON PERFORMANCE OF A LOW SPEED CENTRIFUGAL COMPRESSOR.

27Feb 2017 NUMERICAL SIMULATION ON PERFORMANCE OF A LOW SPEED CENTRIFUGAL COMPRESSOR. S. M. Swamy and V. Panndurangadu. Assistant Professor, Department of Mechanical Engineering, GNITS, Shaikpet, Hyderabad-500104, India. Professor, Department of Mechanical Engineering, JNTUA, Ananthapuramu -515002, A.P, India.

Investigation of two pipe diffuser configurations for a compact centrifugal compressor

Diffusers are one of the most important factors determining the centrifugal compressor performance. The present work is aimed at providing a detailed understanding of the underlying flow and loss mechanisms in three different diffusers in a compact centrifugal compressor stage. Experimental and computational studies were conducted for various diffuser configurations, e.g. two pipe diffusers and one wedge diffuser, while keeping the throat in all the three geometries. It was found that both the pipe diffuser configurations had better aerodynamic performance than the original wedge diffuser. Furthermore, the pipe diffuser with a fishtail arrangement exhibited greater performance improvement, but had more distortion outflow than the wedge diffuser and the radial pipe diffuser because of the strong jet and wake structure caused by the fishtail turn. Nevertheless, the fishtail configuration has a smaller discharge swirl angle, which would have a positive impact on the performance of the combustor. As a result, the fishtail pipe diffuser configuration was recommended in compact centrifugal compressors.

Effect of Fluid Injection to a Leading Edge of Circular Cascade on Centrifugal Compressor Performance

Effect of Fluid Injection to a Leading Edge of Circular Cascade on Centrifugal Compressor Performance

Investigation on steady and unsteady performance of a SCO2 centrifugal compressor with splitters

Supercritical carbon dioxide (SCO2 ) is widely concerned with its excellent physical properties. Its high density helps to achieve a compact mechanical structure, especially in all kinds of turbomachinery. In this paper, a SCO2 centrifugal compressor with splitter blades is displayed and numerically investigated. A thorough numerical analysis of the steady and unsteady performance of this SCO2 centrifugal compressor is performed in ANSYS-CFX with SST turbulence model. Streamlines, pressure and temperature under steady- and unsteady-state are compared and analyzed. Moreover, the trans-critical phenomenon at the leading edge of the rotor blade and the aerodynamic performance are covered. The results in this paper provide the foundation for the design and numerical investigation of SCO2 centrifugal compressors.

Analysis of performance for centrifugal steam compressor

In this study, mean streamline and Computational fluid dynamics (CFD) analyses were performed to investigate the performance of a small centrifugal steam compressor using a latent heat recovery technology. The results from both analysis methods showed good agreement. The compression ratio and efficiency of steam were found to be related with those of air by comparing the compression performances of both gases. Thus, the compression performance of steam could be predicted by the compression performance of air using the developed dimensionless parameters.

Performance improvement of transonic centrifugal compressors by optimization of complex three-dimensional features

Transonic centrifugal compressors with high efficiency and wide stable flow range are required in modern gas turbine engines. Blade design with complex three-dimensional features is one of the promising methods to further improve the performance of such cases. Aiming to increase the efficiency while maintaining similar level of the stable flow range, this article investigates aerodynamic potentials of complex three-dimensional features in a transonic centrifugal compressor by multi-point and multi-objective optimizations, in which the camber curves, the sweep feature, and the lean feature have been optimized. During the first round of optimizations, the aforementioned three groups of variables are optimized individually, and their sensitivities to the performance have been analyzed. When optimizing the camber curves, the best result shows an end-bend feature at the front of the hub section, and the efficiency is improved by 1.0% due to the lowered shock strength. When optimizing the sweep feature, the best result presents an S-shape leading edge and a forward sweep feature. The efficiency is increased by 0.5% because of the reduced wake region. The optimized lean feature only improves the efficiency by 0.2%, which shows its relatively low potential. The final round of optimizations couples both the camber curves and the sweep feature, and the best geometry combines both the end-bend and S-shape leading edge patterns. The peak efficiency and the choke mass flow rate have been increased by 2.2% and 8.1%, respectively, which is owing to the combination of the lowered shock strength by optimized camber curves and the reduced wake region by optimized sweep feature. The result indicates significant potential of complex three-dimensional features to improve the performance of transonic centrifugal compressors.

Effects of volute’s asymmetry on the performance of a turbocharger centrifugal compressor

The effects of the volute’s asymmetry on the performance of a turbocharger centrifugal compressor were studied using steady simulations and theoretical analysis. According to the steady simulation results, it is found that the volute’s asymmetry has significant influence on the performance of the centrifugal compressor. The variation of the stage efficiency due to volute’s asymmetry is up to 4%. Meanwhile, the volute’s asymmetry restricts the compressor stable flow range by imposing a distorted outlet pressure condition and forcing some certain impeller passages to suffer from a worse flow than the others. These certain passages are likely to stall first and trigger the surge, as the stage flow rate further decreases. In other words, the local stall triggers the surge. The relevant flow mechanisms were given to explain the effects based on the three-dimensional flow field, and a new model was developed to demonstrate how the local stall induced by the volute’s asymmetry triggers the system instability.

Effect of internal heat leakage on the performance of a high pressure ratio centrifugal compressor

Centrifugal compressors are widely used in compact gas turbines in industrial and military applications where a high pressure ratio in small size is needed. The trend in centrifugal compressor is high pressure ratios and high efficiencies. However, higher pressure ratio increases the temperature difference between upstream flow and downstream flow which leads to a heat leakage from downstream to upstream through the solid parts. This heat leakage negatively affects the performance as well as the reliability of the compressor. In this study the effect of heat leakage through solid impeller and casing on the compressor performance has been studied for different pressure ratios. The compressor performance has been calculated using a three dimensional numerical model. Conjugate Heat Transfer (CHT) method has been used to calculate the temperature in the solid parts. The results show that the internal heat leakage through both the impeller and casing reduces the efficiency by 2.5% and the total pressure ratio by about 0.83 at pressure ratio up to 11. The effect of the internal heat transfer on the compressor performance is more noticeable at pressure ratios higher than 5. Meanwhile, heat transfer inside the solid impeller alone from the hot region to the cool region reduces the maximum impeller temperature while this heat leakage has a small effect on the compressor performance. However, heat leakage inside the casing alone slightly increases the impeller temperature while it strongly affects the compressor performance.

Optimal design of impeller for centrifugal compressor under the influence of one-way fluid-structure interaction

In this study, a method for optimal design of impeller for centrifugal compressor under the influence of Fluid-structure interaction (FSI) and Response surface method (RSM) was studied. Numerical simulation was conducted using ANSYS Multi-physics with various configurations of impeller geometry. Each of the design parameters was divided into 3 levels. Total 45 design points were planned by Central composite design (CCD) method, which is one of the Design of experiment (DOE) techniques. Response surfaces generated based on the DOE results were used to find the optimal shape of impeller for high aerodynamic performance. The whole process of optimization was conducted using ANSYS Design xplorer (DX). Through the optimization, structural safety and aerodynamic performance of centrifugal compressor were improved.

Effect of the inlet geometry on performance, surge margin and noise emission of an automotive turbocharger compressor

Centrifugal compressor performance at low mass flow rates has become an issue in the latest years due to engine downsizing and the increase of low-end torque request. The principal drawback of this operating region is the appearance of the surge phenomenon, which is strongly affected by the compressor inlet geometry. This work is addressed to study the impact of different inlet geometries on the compressor performance, including compressor efficiency, noise emission and surge margin. An engine test bench is set up with a centrifugal compressor and both steady and transient (tip-out) tests are performed in order to obtain a complete view of the influence of each configuration. The results show a clear sensitivity of the compressor parameters to the variations of the geometry upstream the compressor inlet.

능동형 케이싱 트리트먼트의 형상 변화가 원심압축기의 공력성능에 미치는 영향

능동형 케이싱 트리트먼트의 형상 변화가 원심압축기의 공력성능에 미치는 영향