Transonic Axial Compressors Loss Correlations: Part I — Analysis and Update of Loss Models

2020 ◽  
Author(s):  
Marco Manfredi ◽  
Fabrizio Fontaneto
Keyword(s):  
Axial Compressor ◽  
Reduced Order ◽  
Axial Compressors ◽  
Analysis And Design ◽  
Main Driver ◽  
Validity Range ◽  
Loss Models ◽  
Generation Mechanisms ◽  
Semi Empirical ◽  
System Designs

Abstract The quest for greener, more efficient aircraft engines is the main driver for the development of innovative compression system designs. Reduced order design tools rely nevertheless on semi-empirical loss models, whose validity range is often not net or in general not verified. The present work aims at defining a set of loss correlations, which could readily be employed in the analysis and design process of modern transonic axial compressors. In part I, the main entropy generation mechanisms are described together with a review of the most commonly employed modelling approaches. Selected loss models are then deeper investigated and updated to increase both their range of validity and the accuracy of their predictions. In Part II, the effectiveness of the investigated models will be tested for one specific low aspect ratio axial compressor stage.

Transonic Axial Compressors Loss Correlations: Part II — Loss Models Validation

2020 ◽  
Author(s):  
Marco Manfredi ◽  
Cedric Babin ◽  
Fabrizio Fontaneto
Keyword(s):  
Axial Compressor ◽  
Numerical Data ◽  
Axial Compressors ◽  
Analysis And Design ◽  
Main Driver ◽  
Validity Range ◽  
Loss Models ◽  
Models Validation ◽  
Semi Empirical ◽  
System Designs

Abstract The quest for greener, more efficient aircraft engines is the main driver for the development of innovative compression system designs. Reduced order design tools rely nevertheless on semi-empirical loss models, whose validity range is often not net or in general not verified. The present work aims at defining a set of loss correlations, which could readily be employed in the analysis and design process of modern transonic axial compressors. In Part I, various loss correlations were deeply described and, in some cases, updated to enhance both their generality and their prediction capability. In Part II, the effectiveness of both original and updated models will be tested for one specific low aspect ratio axial compressor stage. Experimental and numerical data will be used at such extent.

Axial Compressor Performance Prediction Using Improved Streamline Curvature Approach

2018 ◽  
Author(s):  
Tao Li ◽  
Yadong Wu ◽  
Hua Ouyang ◽  
Xiaoqing Qiang
Keyword(s):  
Performance Prediction ◽  
Incidence Angle ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Internal Flow ◽  
Field Calculation ◽  
Axial Compressors ◽  
Streamline Curvature ◽  
Loss Models

This paper presents in detail the improved streamline curvature approach (SLC) to the performance evaluation and internal flow field calculation of subsonic and transonic axial compressors. Based on previous research, the diverse incidence, deviation and total pressure loss models, generally existing in the form of fitting curves and semi-empirical correlations, are discussed respectively. Typically, transonic flow in axial compressor results in the variation of several flow parameters and particularly the appearance of shock waves compared with subsonic flow. In this paper, the revision and improvement of loss models are applied to reach higher accuracy, especially considering the loss component due to actual incidence angle. Several modifications have been made as well considering the influence of three-dimensional flow. For the purpose of validating this approach, two test cases, including a single-stage transonic axial compressor NASA Stage37 and a 3-stage subsonic axial compressor P&W 3S1, are calculated. The overall characteristics and spanwise aerodynamic parameters for blade rows are demonstrated at both design and off-design conditions. Furthermore, the results agree well with both experimental data and computational fluid dynamic (CFD) results. This throughflow method is verified as an applicable and convenient tool for aerodynamic analysis and performance prediction of subsonic and transonic axial compressors.

scholarly journals Inter-Stage Dynamic Performance of an Axial Compressor of a Twin-Shaft Industrial Gas Turbine

Machines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 83
Author(s):  
Samuel Cruz-Manzo ◽  
Senthil Krishnababu ◽  
Vili Panov ◽  
Chris Bingham
Keyword(s):  
Gas Turbine ◽  
Dynamic Performance ◽  
Axial Compressor ◽  
Modeling Framework ◽  
Axial Compressors ◽  
Stage Performance ◽  
Compressor Map ◽  
Stage Characteristic ◽  
Industrial Gas Turbine ◽  
Semi Empirical

In this study, the inter-stage dynamic performance of a multistage axial compressor is simulated through a semi-empirical model constructed in the Matlab Simulink environment. A semi-empirical 1-D compressor model developed in a previous study has been integrated with a 0-D twin-shaft gas turbine model developed in the Simulink environment. Inter-stage performance data generated through a high-fidelity design tool and based on throughflow analysis are considered for the development of the inter-stage modeling framework. Inter-stage performance data comprise pressure ratio at various speeds with nominal variable stator guide vane (VGV) positions and with hypothetical offsets to them with respect to the gas generator speed (GGS). Compressor discharge pressure, fuel flow demand, GGS and power turbine speed measured during the operation of a twin-shaft industrial gas turbine are considered for the dynamic model validation. The dynamic performance of the axial-compressor, simulated by the developed modeling framework, is represented on the overall compressor map and individual stage characteristic maps. The effect of extracting air through the bleed port in the engine center-casing on transient performance represented on overall compressor map and stage performance maps is also presented. In addition, the dynamic performance of the axial-compressor with an offset in VGV position is represented on the overall compressor map and individual stage characteristic maps. The study couples the fundamental principles of axial compressors and a semi-empirical modeling architecture in a complementary manner. The developed modeling framework can provide a deeper understanding of the factors that affect the dynamic performance of axial compressors.

Application of Smith Chart for Non-Repeating Stages in Axial Compressors

2013 ◽  
Author(s):  
Daniel Hernández ◽  
Antonio Antoranz ◽  
Raúl Vázquez
Keyword(s):  
Early Stage ◽  
Axial Compressor ◽  
Preliminary Design ◽  
The Novel ◽  
Flow Angle ◽  
Axial Compressors ◽  
Absolute Flow ◽  
Final Design ◽  
Semi Empirical ◽  
Smith Chart

The configuration of an axial compressor, including the mean radius, the annulus lines, stage loading or number of stages, flow parameter, work split and stage reactions, are all of them selected in the preliminary design phase. For the success of the final design, to attain the proper selection is mandatory. A representative geometry of the airfoils is not available at this early stage of the design process. Therefore the former parameters use to be selected based only on the designer prior experience and/or empirical correlations. Under these circumstances, the so called Smith Chart is a valuable tool that can provide simple guidelines to the designer and a preliminary assessment of the compressor efficiency. The use of this chart can be also extended to get the main features of the airfoils, like flow angles, turning, Mach and Reynolds number, diffusion factor, aspect ratio, etc. as well as to compare different design candidates. Several authors have produced their own diagrams by analytical or semi-empirical approach. The repeating stage hypothesis, which has been usually assumed, implies no change in inlet and outlet absolute flow angles and constant axial velocity throughout the stage. The density rise through the stage is compensated by reducing the annulus height and so the annulus wall slope along the compressor is directly obtained from the continuity equation, being in most of the cases not representative of real compressors. In order to have a more representative annulus, in the present work, the repeating stage hypothesis has not been assumed. The annulus shape (height and slope wall angle) is therefore defined by the designer and in order to close the equations of the problem, the absolute exit flow angle of every stage is required. The optimization of the compressor by the novel proposed method is more complicate because of the higher number of variables. However the method has the advantage to reduce the design iterations due to its more reliable results. The aim of this paper is to introduce the novel method of non-repeating stages and to show how this approach can be used in the preliminary design of an axial compressor.

Three-Dimensional Flows and Loss Reduction in Axial Compressors

1987 ◽  
Vol 109 (3) ◽  
pp. 354-361 ◽  
Author(s):  
Y. Dong ◽  
S. J. Gallimore ◽  
H. P. Hodson
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Axial Flow ◽  
Tracer Gas ◽  
Suction Surface ◽  
Axial Compressors ◽  
Small Clearance ◽  
Oil Flow ◽  
Stator Blade ◽  
Flow Compressor

Measurements have been performed in a low-speed high-reaction single-stage axial compressor. Data obtained within and downstream of the rotor, when correlated with the results of other investigations, provide a link between the existence of suction surface–hub corner separations, their associated loss mechanisms, and blade loading. Within the stator, it has been shown that introducing a small clearance between the stator blade and the stationary hub increases the efficiency of the stator compared to the case with no clearance. Oil flow visualizaton indicated that the leakage reduced the extensive suction surface–hub corner separation that would otherwise exist. A tracer gas experiment showed that the large radial shifts of the surface streamlines indicated by the oil flow technique were only present close to the blade. The investigation demonstrates the possible advantages of including hub clearance in axial flow compressor stator blade rows.

Numerical Investigation of a Cantilevered Compressor Stator at Varying Clearance Sizes

2015 ◽  
Author(s):  
Chengwu Yang ◽  
Xingen Lu ◽  
Yanfeng Zhang ◽  
Shengfeng Zhao ◽  
Junqiang Zhu
Keyword(s):  
Flow Field ◽  
Axial Compressor ◽  
High Flow ◽  
Leakage Flow ◽  
Streamwise Direction ◽  
Stall Margin ◽  
Axial Compressors ◽  
Pressure Surface ◽  
The Impact ◽  
Highly Loaded

The clearance size of cantilevered stators affects the performance and stability of axial compressors significantly. Numerical calculations were carried out using the commercial software FINE/Turbo for a 2.5-stage highly loaded transonic axial compressor, which is of cantilevered stator for the first stage, at varying hub clearance sizes. The aim of this work is to improve understanding of the impact mechanism of hub clearance on the performance and the flow field in high flow turning conditions. The performance of the front stage and the compressor with different hub clearance sizes of the first stator has been analyzed firstly. Results show that the efficiency decreases as clearance size varies from 0 to 3% of hub chordlength, but the operating range has been extended. For the first stage, the efficiency decreases about 0.5% and the stall margin is extended. The following analysis of detailed flow field in the first stator shows that the clearance leakage flow and elimination of hub corner separation is responsible for the increasing loss and stall margin extending respectively. The effects of hub clearance on the downstream rotor have been discussed lastly. It indicates that the loss of the rotor increases and the flow deteriorates due to increasing of clearance size and hence the leakage mass flow rate, which mainly results from the interaction of upstream leakage flow with the passage flow near pressure surface. The affected region of rotor passage flow field expands in spanwise and streamwise direction as clearance size grows. The hub clearance leakage flow moves upward in span as it flows toward downstream.

Geometric-control formulation and averaging analysis of the unsteady aerodynamics of a wing with oscillatory controls

2021 ◽  
Vol 928 ◽  
Author(s):  
Haithem E. Taha ◽  
Laura Pla Olea ◽  
Nabil Khalifa ◽  
Cody Gonzalez ◽  
Amir S. Rezaei
Keyword(s):  
Control Theory ◽  
Stokes Equations ◽  
Unsteady Aerodynamics ◽  
Geometric Control ◽  
Navier Stokes ◽  
Analysis Tool ◽  
Geometric Control Theory ◽  
Reduced Order ◽  
Nonlinear Control Theory ◽  
Generation Mechanisms

Differential-geometric-control theory represents a mathematically elegant combination of differential geometry and control theory. Practically, it allows exploitation of nonlinear interactions between various inputs for the generation of forces in non-intuitive directions. Since its early developments in the 1970s, the geometric-control theory has not been duly exploited in the area of fluid mechanics. In this paper, we show the potential of geometric-control theory in the analysis of fluid flows, exemplifying it as a heuristic analysis tool for discovery of symmetry-breaking and unconventional force-generation mechanisms. In particular, we formulate the wing unsteady aerodynamics problem in a geometric-control framework. To achieve this goal, we develop a reduced-order model for the unsteady flow over a pitching–plunging wing that is (i) rich enough to capture the main physical aspects (e.g. nonlinearity of the flow dynamics at large angles of attack and high frequencies) and (ii) efficient and compact enough to be amenable to the analytic tools of geometric nonlinear control theory. We then combine tools from geometric-control theory and averaging to analyse the developed reduced-order dynamical model, which reveals regimes for lift and thrust enhancement mechanisms. The unsteady Reynolds-averaged Navier–Stokes equations are simulated to validate the theoretical findings and scrutinize the underlying physics behind these enhancement mechanisms.

A Reduced-Order Model for the Preliminary Design of Small-Scale Radial Inflow Turbines

2021 ◽  
Author(s):  
Marco Manfredi ◽  
Marco Alberio ◽  
Marco Astolfi ◽  
Andrea Spinelli
Keyword(s):  
Heat Recovery ◽  
Internal Combustion Engines ◽  
Reduced Order Model ◽  
Pollutant Emissions ◽  
Small Scale ◽  
Preliminary Design ◽  
Order Model ◽  
Reduced Order ◽  
Wide Range ◽  
Loss Models

Abstract Power production from waste heat recovery represents an attractive and viable solution to contribute to the reduction of pollutant emissions generated by industrial plants and automotive sector. For transport applications, a promising technology can be identified in bottoming mini-organic Rankine cycles (ORCs), devoted to heat recovery from internal combustion engines (ICE). While commercial ORCs exploiting turbo-expanders in the power range of hundreds kW to several MW are a mature technology, well-established design guidelines are not yet available for turbines targeting small power outputs (below 50 kW). The present work develops a reduced-order model for the preliminary design of mini-ORC radial inflow turbines (RITs) for high-pressure ratio applications, suitable to be integrated in a comprehensive cycle optimization. An exhaustive review of existing loss models, whose development pattern is retraced up to the original approaches, is proposed. This investigation is finalized in a loss models effectiveness analysis performed by testing several correlations over six existing geometries. These test case turbines, operating with different fluids and covering a wide range of target expansion ratio, size, and gross power output, are then employed to carry out the validation procedure, whose results prove the robustness and prediction capability of the proposed reduced-order model.

scholarly journals Simplified Method for Flow Analysis and Performance Calculation Through an Axial Compressor

1984 ◽  
Author(s):  
Hubert Miton ◽  
Youssef Doumandji ◽  
Jacques Chauvin
Keyword(s):  
Equations Of Motion ◽  
Computing Time ◽  
Flow Analysis ◽  
Axial Compressor ◽  
Computation Method ◽  
Duct Flow ◽  
Axial Compressors ◽  
Flow Through ◽  
And Performance ◽  
Performance Calculation

This paper describes a fast computation method of the flow through multistage axial compressors of the industrial type. The flow is assumed to be axisymmetric between the blade rows which are represented by actuator disks. Blade row losses and turning are calculated by means of correlations. The equations of motion are linearized with respect to the log of static pressure, whose variation along the radius is usually of limited extent for the type of machines for which the method has been developed. In each computing plane (i.e. between the blade rows) two flows are combined: a basic flow with constant pressure satisfying the mass flow requirements and a perturbation flow fulfilling the radial equilibrium condition. The results of a few sample calculations are given. They show a satisfactory agreement with a classical duct flow method although the computing time is reduced by a factor five. The method has also been coupled with a surge line prediction calculation.

scholarly journals Radial Transport and Momentum Exchange in an Axial Compressor

1992 ◽  
Author(s):  
Robert P. Dring
Keyword(s):  
Secondary Flow ◽  
Diffusion Model ◽  
Turbulent Diffusion ◽  
Flow Model ◽  
Axial Compressor ◽  
Momentum Exchange ◽  
Radial Transport ◽  
Axial Compressors ◽  
Mixing Coefficient ◽  
Spanwise Location

The objective of this work was to examine radial transport in axial compressors from two perspectives. The first was to compare the mixing coefficient based on a secondary flow model (using measured radial velocities) with that based on a turbulent diffusion model. The second was to use measured airfoil pressure forces and momentum changes to assess the validity of the assumption of diffusive radial transport which is common to both models. These examinations were carried out at both design and off-design conditions as well as for two rotor tip clearances. In general it was seen that radial mixing was strongest near the hub and that it increased dramatically at near-stall conditions. It was also seen that radial transport could cause large differences (≈ 100%) between the force on an airfoil and the change in momentum across the airfoil at the same spanwise location.

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