Download or read book Technique to Predict Stage by stage Pre stall Compressor Performance Characteristics Using a Streamline Curvature Code with Loss and Deviation Correlations written by Jason Brent Klepper and published by . This book was released on 1998 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Incorporation of High fidelity Flow Field Information Into Preliminary Design of Multi stage Axial Compressors written by Alexander Timo Jörger and published by . This book was released on 2021 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis establishes an axisymmetric methodology that incorporates pre-performed high-fidelity CFD into the performance estimation of multi-stage axial compressors during preliminary design. Its key differentiator is that radial non-uniformity, inferred from three-dimensional CFD and represented using orthonormal basis functions, replaces empirical correlations of blockage, loss, and deviation as well as simplified models of flow features, such as boundary-layer growth, spanwise mixing, and endwall-corner separation. The methodology includes the effects of changes in radial non-uniformity and in blade geometry on the axisymmetric flow field. The approach can supersede current throughflow methods, increasing the fidelity of preliminary design. The primary impact of the methodology is a new capability for power gas turbine compressors to rapidly assess off-design matching at different spanwise locations along the blade height, enabling early-design choices, such as the annulus-area scheduling, based on the fidelity of CFD. Over a range of off-design conditions from near stall to near choke, the massflow capacity of a four-stage compressor was estimated within 1.2% and its efficiency within 1.5 percentage points compared to CFD at equal loading. The estimation of quasi-one-dimensional performance and the characterization of the flow close to the endwalls are improved relative to estimations of a legacy streamline curvature method since radial non-uniformity is inferred from high-fidelity flow field information. The methodology is demonstrated to be suitable for incorporation into compressor design systems.
Download or read book Off Design Computer Code for Calculating the Aerodynamic Performance of Axial Flow Fans and Compressors written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11-07 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: An off-design axial-flow compressor code is presented and is available from COSMIC for predicting the aerodynamic performance maps of fans and compressors. Steady axisymmetric flow is assumed and the aerodynamic solution reduces to solving the two-dimensional flow field in the meridional plane. A streamline curvature method is used for calculating this flow-field outside the blade rows. This code allows for bleed flows and the first five stators can be reset for each rotational speed, capabilities which are necessary for large multistage compressors. The accuracy of the off-design performance predictions depend upon the validity of the flow loss and deviation correlation models. These empirical correlations for the flow loss and deviation are used to model the real flow effects and the off-design code will compute through small reverse flow regions. The input to this off-design code is fully described and a user's example case for a two-stage fan is included with complete input and output data sets. Also, a comparison of the off-design code predictions with experimental data is included which generally shows good agreement. Schmidt, James F. Unspecified Center...
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1961 with total page 1096 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modification of a One dimensional Dynamic Compression System Model to Calculate Stage Characteristics Internally written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A one-dimensional, dynamic gas turbine engine performance analysis program, based on a modified parallel compressor theory, was enhanced with an added capability to calculate compressor stage characteristics given basic blade correlations, blade and casing geometry, and flow conditions. Total pressure ratio and total temperature ratio across rotors and stators had previously been provided solely by stage characteristics maps created using experimental data or computational means. The user now has the option to have those ratios, or characteristics, calculated via a one-dimensional code during the simulation. Experimental data is still required for calibration of this characteristics prediction code. An existing characteristics prediction code was integrated as a subroutine of the performance analysis program. With flow conditions at the stage inlet and basic stage geometry information provided, the characteristics prediction code calculates the desired ratios and feeds them back to the analysis code. The performance analysis program interacts with the characteristic prediction code whenever rotor or stator performance is required, so it can be run in a steady state or dynamic condition, with or without parallel compressor theory. The modifications allow it to simulate radial and circumferential mass redistribution, as well as radial work redistribution between the parallel flow segments. These, in turn, make it possible to model the effects of radial and circumferential inlet flow distortion on overall compressor performance. The interface with the characteristic prediction code enables separate characteristics to be calculated for each parallel flow segment. The characteristics prediction code calculates the stage pressure and temperature ratios along an averaged streamline, or meanline. Called the Meanline Code (capitalized to specify the particular algorithm used here), this code uses a correlation to provide stage loss and deviation. Since the correlation used is not sufficiently general, add-loss and add-deviation values are tabulated, or mapped, against corrected mass flow. The one-dimensional Meanline Code performs its calculations along a streamline specified by the meanline velocity density ratio (MVDR), also tabulated against mass flow in the map. The modeling technique and calibration process were validated using experimental data from NASA Rotor 1B, a single rotor compressor test bed. The new capability to calculate stage characteristics directly makes it possible to perform analyses of an engine without detailed compressor stage performance data. It also takes an important step toward increasing DYNTECC's capabilities.
Download or read book Compressor Instability with Integral Methods written by Eddie Y.K. Ng and published by Springer Science & Business Media. This book was released on 2007-07-07 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together the quick integral approaches and advances in the field for the prediction of stall and surge problems in the compressor. The book is useful for people involved in the flow analysis, design and testing of rotating machinery. For students, it can be used as a specialized topic of senior undergraduate or graduate study. The book can also serve as self-study material.
Download or read book ASME Technical Papers written by and published by . This book was released on 1976 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Prediction of an Axial Compressor Stage Characteristic from a One point Measurement written by Shahnaz M. Punjani and published by . This book was released on 1995 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book STGSTK A Computer Code for Predicting Multistage Axial Flow Compressor Performance by a Meanline Stage Stacking Method written by and published by . This book was released on 1982 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Methodology to Estimate Aero performance and Aero operability Limits of a Multistage Axial Flow Compressor for Use in Preliminary Design written by Sameer Kulkarni and published by . This book was released on 2012 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The preliminary design of multistage axial compressors in gas turbine engines is typically accomplished with mean-line methods. These methods, which rely on empirical correlations, estimate compressor performance well near the design point, but may become less reliable off-design. For land-based applications of gas turbine engines, off-design performance estimates are becoming increasingly important, as turbine plant operators desire peaking or load-following capabilities and hot-day operability. The current work implements a one-dimensional stage stacking procedure, including a new blockage term, which is used to estimate off-design compressor performance and operability range of a 13-stage axial compressor used for power generation. The procedure utilizes stage characteristics which are constructed from computational fluid dynamics (CFD) simulations of groups of stages. The stage stacking estimates match well with CFD results. These CFD results are used to assess a metric which estimates the stall limiting stages.
Download or read book Predicting Stage Performance of a Multi stage Centrifugal Compressor Using the Overall Compressor Performance Characteristic written by Dirk Cornelius Human and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The reliable operation of Integrally Geared Centrifugal Compressors (IGCCs), used in the coal-fired power generation industry of South Africa, is essential for economic, environmental and safety considerations. However, due to the unavailability of individual stage performance curves, the ability of a compressor owner to identify underperforming stages to maintain these compressors proactively remains limited. This study addresses the stage performance prediction of an IGCC when only the compressor's overall performance characteristic, in conjunction with the impeller diameters and tip speeds, are known. The study is limited to IGCCs used in the coal-fired power generation industry of South Africa. Based on the limited inputs, two performance modelling methods were considered for this application, namely stage stacking and 1-dimensional modelling. However, stage stacking requires known operating points on each stage performance curve from which the rest of the curve can be extrapolated while 1-dimensional models require detailed stage design information to model stage performance. This study developed a revised stage stacking procedure which in contrast to the traditional stage stacking procedure, does not require a known operating point on each stage's performance curve, for it assesses the relative stage performance at the compressor's surge flow rate. The relative maximum pressure ratio of each stage is acquired through the application of similarity principles while a simplified 1-dimensional impeller analysis model is used to assess relative impeller head coefficients. The modelling process was developed based on performance and design data for IGCCs obtained from a compressor manufacturer. Performance data of four IGCCs, consisting of 13 stages, were obtained, including the design data for ten impellers. Hence, the IGCCs satisfy the requirements of geometric and aerodynamic similarity, unveiling a linear relationship between the stage impeller tip speed and maximum pressure ratio. A simplified 1-dimensional performance model was used to assess relative impeller head coefficients. A verification procedure ensured the integrity of the findings of the 1-dimensional model was maintained by comparing the model results to findings obtained using commercial compressor performance modelling software. A sensitivity analysis was conducted on the 1-dimensional performance model to ascertain which input parameters could be scaled as a function of the impeller tip diameter. For the four IGCCs for which data were obtained, the stage-discharge pressure and isentropic efficiency curves were calculated using the developed model. The maximum variation between the measured and calculated pressure and isentropic efficiency curves equaled 8.20% and 10.84%, respectively. The prediction accuracy of the developed modelling procedure is similar to map-based models found in literature and is considered adequate for identifying an underperforming stage. Thus, the developed model could serve as a valuable conditioning monitoring tool for site-based compressor owners.
Download or read book Dimension Determination of Precursive Stall Events in a Single Stage High Speed Compressor written by and published by . This book was released on 1996 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Near stall Performance Prediction for a Low Speed Single Stage Compressor written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics is used to model turbomachinery compressor performance throughout the entire operating range. While it can be very accurate for peak performance calculations, it often is inaccurate around near-stall. CFD tends to predict too large of a peak pressure rise. A few reasons are proposed and explored during the course of this thesis: 1) The complexities of tip modeling 2) Stator loss and blockage on the compressor 3) Multi-bladerow effects 4) Unsteady effects. All analyses tested on the compressor rotor used by Masahiro Inoue. A multi-block grid was used to adequately model the clearance gap. A standard Wilcox k-w turbulence model was used. Steady single blade row and multi-bladerow analysis were done. An unsteady single bladerow analysis was also made. The implementation of a Low Speed Pre-conditioner and Matrix Dissipation were also studied to see their benefits on the convergence and performance prediction of this rotor. The results were plotted on a compressor speedline of total pressure rise coefficient vs. exit corrected flow. This allowed for comparisons between the tested cases. These results were compared with published experimental results. Steady state results were close to experimental data at design point, but over-predicted the pressure rise as the compressor was throttled toward stall. Adding the stator loss from the multi-bladerow analysis was a significant improvement to this accuracy, as the stator was shown to have large separation, but still over-predicted the pressure rise. It was determined that there was little or no multi-bladerow interaction. Unsteady analysis of the rotor alone resulted in little additional loss before stall, but greatly improved accuracy for flow coefficients lower than the peak pressure rise where unsteady effects are prevalent. The numerical analysis required to achieve accuracy in compressor modeling depends on the area of the speedline. Near design point, steady state, rotor-alone analysis may be sufficient. As the compressor nears stall, it is important to take into consideration turbulence effects and all rotors and stators. For flow coefficients lower than the peak pressure rise of the compressor speedline, unsteady analysis is required to achieve accurate results.
Download or read book A Wide Range Axial Flow Compressor Stage Performance Model written by Gregory S. Bloch and published by . This book was released on 1991 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic compression system response is a major concern in the operability of aircraft gas turbine engines and computer models have been developed to predict compressor response to changing operating conditions. These models require a knowledge of the steady-stage operating characteristics as inputs, which limits the ability to use them as predicting tools. The full range of dynamic axial flow compressor operation spans forward and reversed flow conditions. A model for predicting the wide flow range characteristics of axial flow compressor stages has been developed and a parametric study of the effect of changing design variables on steady-state performance has been conducted. The model was applied to a 3-stage, low-speed compressor with very favorable results and to a 10-stage, high-speed compressor with mixed results. Conclusions were made regarding the inception of stalling and the effects associated with operating a stage in a multistage environment. It was also conclude that there are operating points of an isolated compressor stage that are not attainable when that stage is operated in a multistage environment. Axial Compressor, Stalling Performance, Aircraft Turbine, Engine, Performance Prediction.
Download or read book Stage Effects on Stalling and Recovery of a High Speed 10 Stage Axial Flow Compressor written by William W. Copenhaver and published by . This book was released on 1990 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of a High-speed 10-stage axial-flow compressor test involving overall compressor and individual stage performance while stalling and operating in quasi-steady rotating stall are described. Test procedures and data acquisition methods used to obtain the dynamic stalling and quasi-steady in-stall data are explained. Unstalled and in-stall data obtained from the compressor operating at five different shaft speeds and one off-schedule variable vane condition are presented. The effects of compressor speed and variable geometry on overall compressor in-stall pressure rise and hysteresis extent are illustrated through the use of quasi-steady stage temperature and pressure rise characteristics. The results indicate that individual stage performance during overall compressor. Time resolved install data acquired at two different shaft speeds are presented in support of the notion that stage operation varies significantly from entrance to exit of the compressor. Both time-averaged and time-resolved individual stage results suggest that stage matching is important, not only for unstalled performance but also for in-stall performance and recoverability from stall. The measured high-speed 10-stage test compressor individual stage pressure and temperature characteristics were input into a stage-by-stage dynamic compressor performance model. The analytical model had been previously validated for the prediction of low-speed compressor stalling and in-stall performance. (SDW).
Download or read book Analytical Correlation of Centrifugal Compressor Design Geometry for Maximum Efficiency with Specific Speed written by Michael R. Galvas and published by . This book was released on 1972 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Centrifugal compressor performance was examined analytically to determine optimum geometry for various applications as characterized by specific speed. Seven specific losses were calculated for various combinations of inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, blade exit backsweep, and inlet-tip absolute tangential velocity for solid body prewhirl. The losses considered were inlet guide vane loss, blade loading loss, skin friction loss, recirculation loss, disk friction loss, vaneless diffuser loss, and vaned diffuser loss. Maximum total efficiencies ranged from 0.497 to 0.868 for a specific speed range of 0.257 to 1.346. Curves of rotor exit absolute flow angle, inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, head coefficient and blade exit backsweep are presented over a range of specific speeds for various inducer tip speeds to permit rapid selection of optimum compressor size and shape for a variety of applications.
