Automated Aerodynamic Optimization of an Aggressive S-Shaped Intermediate Compressor Duct

2018 ◽  
Author(s):  
T. Stürzebecher ◽  
G. Goinis ◽  
C. Voss ◽  
H. Sahota ◽  
P. Groth ◽  
...  
Keyword(s):  
Guide Vane ◽  
Aerodynamic Optimization ◽  
Baseline Design ◽  
Separating Flow ◽  
High Pressure Compressor ◽  
Important Research Topic ◽  
Final Design ◽  
Endwall Contouring ◽  
Aero Engines ◽  
Pressure Compressor

As bypass-ratio in modern aero engines is continuously increasing over the last decades, the radial offset between low pressure compressor (LPC) and high pressure compressor (HPC), which needs to be overcome by the connecting s-shaped intermediate compressor duct (ICD), is getting higher. Due to performance and weight saving aspects the design of shorter and therefore more aggressive ducts has become an important research topic. In this paper an already aggressive design (with respect to current aero engines) of an ICD with integrated outlet guide vane (OGV) is used as a baseline for an aerodynamic optimization. The aim is to shorten the duct even further while maintaining it separation free. The optimization is broken down into two steps. In the first optimization-step the baseline design is shortened to a feasible extent while keeping weak aerodynamic restrictions. The resulting highly aggressive duct (intermediate design), which is shortened by 19 % in axial length with respect to the baseline, shows separation tendencies of low momentum fluid in the strut/hub region. For the second step, the length of the optimized duct design is frozen. By implementing new design features in the process of the optimizer, this optimization-step aims to eliminate separation and to reduce separation tendencies caused by the aggressive shortening. In particular, these features are: a nonaxisymmetric endwall contouring and parametrization of the strut and the OGV to allow for changes in lift and turning in both blade designs. By comparison of the three designs: Baseline, intermediate (separating flow) and final design, it can be shown, that it is possible to decrease length of the already aggressive baseline design even further, when adding a nonaxisymmetric endwall contouring and changes in blade shape of the strut and OGV. Flow separation can be eliminated while losses are kept low. With a more aggressive and therefore shorter duct the engine length and weight can be reduced. This in turn leads to lighter aircrafts, less fuel consumption and lower CO2 and NOx emissions.

AERODYNAMIC INFLUENCE OF A BLEED ON THE LAST STAGE OF A LOW-PRESSURE COMPRESSOR AND S-DUCT

2021 ◽  
pp. 1-39
Author(s):  
Apostolos Spanelis ◽  
A Duncan Walker
Keyword(s):  
Radial Flow ◽  
Guide Vane ◽  
Low Pressure ◽  
Flow Distortion ◽  
Tip Leakage ◽  
High Pressure Compressor ◽  
Unsteady Rans ◽  
Last Stage ◽  
Flow Variables ◽  
Pressure Compressor

Abstract This paper uses Computational Fluid Dynamics to investigate the effect of an engine handling bleed situated on the outer casing downstream of the last rotor stage of a low-pressure compressor and upstream of the outlet guide vane and S-shaped duct. The model, validated against existing experimental data, utilized an unsteady RANS solver incorporating a Reynolds stress closure to examine the unsteady component interactions. The results showed that at bleed rates less than 25% of the mainstream flow the bleed effects were negligible. However, at higher bleed rates performance was significantly degraded. A uniform flow extraction hypothesis was employed to separate the positional bias effects from the bulk flow diffusion. This revealed that the bleed-induced radial flow distortion can significantly affect the OGV loading distribution, which thereby dictates the position and type of stall within the OGV passage. Extraction of the rotor tip leakage via the shroud bleed, combined with the radial flow distortion, contributed to a 28% reduction in duct loss at 10% bleed and up to 50% reduced loss at 25% bleed. The actual amount of flow required to be extracted for an OGV stall to develop, was 30%. That was independent of the bleed location and the type of stall. For bleeds up to 20%, the S-duct displayed a remarkable resilience and consistency of flow variables at duct exit. However, a stalled OGV deteriorated the radial flow uniformity that was presented to the high-pressure compressor.

An Experimental Investigation of a Tandem Stator Flow Characteristic in a Low Speed Axial Research Compressor

2014 ◽  
Author(s):  
Alrik Tesch ◽  
Martin Lange ◽  
Konrad Vogeler ◽  
Jens Ortmanns ◽  
Erik Johann ◽  
...  
Keyword(s):  
Swirling Flow ◽  
Guide Vane ◽  
Axial Compressor ◽  
Low Speed ◽  
High Pressure Compressor ◽  
Oil Flow ◽  
Compressor Performance ◽  
Operating Points ◽  
Insight Into ◽  
Pressure Compressor

A major goal in axial compressor development is to increase the efficiency and to reduce the weight of the module. In order to do so the power density has to be increased by raising the work per stage. Higher capability to do work can be achieved by increasing the circumferential velocity component of the fluid. Tandem stators might offer the ability to turn high swirling flow with lower losses compared to a single blade stator. In terms of higher aerodynamic loading the use of tandem vanes can be a key feature to allow the design of highly efficient and compact compressor modules. This paper presents the design and experimental validation of a single stage low speed axial compressor with a tandem outlet guide vane, representative for a modern jet engine high pressure compressor. Additionally to the overall compressor performance the 3D flow field of the tandem stator has been measured with a five hole probe at different operating points. The results will be discussed in comparison with numerical results. Furthermore, oil flow pictures are used to get a deeper insight into flow conditions inside the vane passage and to validate the numerically predicted secondary flow structures.

scholarly journals Technology Making It Into Production

2009 ◽  
Vol 131 (03) ◽  
pp. 53-53
Author(s):  
Glinter Wilfert
Keyword(s):  
European Union ◽  
High Pressure ◽  
Heat Exchanger ◽  
High Speed ◽  
Low Pressure ◽  
The European Union ◽  
Low Pressure Turbine ◽  
High Pressure Compressor ◽  
Aero Engines ◽  
Pressure Compressor

This paper discusses the concept of MTU Aero Engines’ high-speed low-pressure turbine for the geared turbofan, which is based on the European Union research program ‘Clean’. Under the program, MTU developed the high-speed low-pressure turbine, the turbine centre frame, and an integrated heat exchanger. The paper also highlights that Pratt & Whitney, launched its geared turbofan (GTF) demonstrator project and asked MTU to be a partner. MTU has secured a 15 percent stake in either GTF version, which brings its high-speed low-pressure turbine, plus the first four stages of the high-pressure compressor.

An Assessment of a Turbofan Engine Using Catalytic Interturbine Combustion

2009 ◽  
Author(s):  
Richard Avella´n ◽  
Tomas Gro¨nstedt
Keyword(s):  
Catalytic Combustion ◽  
Substantial Reduction ◽  
Parameter Study ◽  
Preliminary Design ◽  
Nox Formation ◽  
Technical Feasibility ◽  
Turbofan Engine ◽  
High Pressure Compressor ◽  
Aero Engines ◽  
Pressure Compressor

The potential for using catalytic combustion in aero engines is discussed. Some preliminaries relating to NOx formation and material capabilities are analyzed. Various means to integrate catalytic combustors in aero engines are described. In particular, catalytic interturbine combustion is investigated both in terms of technical feasibility and through a preliminary design exercise. A thermodynamic design point study is presented analyzing a configuration with a combustor located concentrically around the engine core receiving pressurized air through an interstage high pressure compressor bleed. A parameter study of the compressor bleed ratio is presented for the configuration. A substantial reduction in NOx emissions at the expense of an increase in mission fuel consumption is observed.

Compressor Casing Preliminary Design Based on Features

2008 ◽  
Author(s):  
Stefan Bretschneider ◽  
Frank Rothe ◽  
Martin G. Rose ◽  
Stephan Staudacher
Keyword(s):  
Design Method ◽  
Design Tool ◽  
Preliminary Design ◽  
Revolution Speed ◽  
High Pressure Compressor ◽  
Design Perspective ◽  
Structural Parts ◽  
Aero Engines ◽  
The Individual ◽  
Pressure Compressor

Structural parts, such as casings, have a significant share of the overall turbo-machinery mass of modern aero-engines. Therefore preliminary design studies must aim to include the effect of such structures. For this paper compressor casings of commercial aero-engines have been investigated in terms of their design philosophy. It is shown that compressor casings have very similar designs from the preliminary design perspective, even though they appear as very complex structures in reality. The study identified design similarities from which generalized and simplified casing structures have been derived. The casing is divided into geometrically similar basic structures. Such generalized parts are each individually characterized by features. Through simplified physical design algorithms the features are then dimensioned based on blade containment conditions, pressures and temperatures. Finally a generalized form of compressor casing design is derived from the assembly of the individual parts. The derived preliminary design method of casings is no longer dependent on a known representative casing thickness. When increasing compressor characteristics such as blade numbers, diameters or revolution speed the casing design responds directly while still maintaining a characteristic shaping philosophy. Thus a scaling method based on physics rather than only geometrical identity is achieved. The method was integrated into an existing high pressure compressor preliminary design tool. The examination of the developed methodology is carried out against existing compressor designs. Results are presented and discussed.

Review on the aerodynamics of intermediate compressor duct

2020 ◽  
Vol 14 (4) ◽  
pp. 7446-7468
Author(s):  
Manish Sharma ◽  
Beena D. Baloni
Keyword(s):  
High Pressure ◽  
Pressure Loss ◽  
Flow Analysis ◽  
Outer Wall ◽  
Optimization Techniques ◽  
Optimum Pressure ◽  
Research Areas ◽  
Static Pressure Distribution ◽  
High Pressure Compressor ◽  
Pressure Compressor

In a turbofan engine, the air is brought from the low to the high-pressure compressor through an intermediate compressor duct. Weight and design space limitations impel to its design as an S-shaped. Despite it, the intermediate duct has to guide the flow carefully to the high-pressure compressor without disturbances and flow separations hence, flow analysis within the duct has been attractive to the researchers ever since its inception. Consequently, a number of researchers and experimentalists from the aerospace industry could not keep themselves away from this research. Further demand for increasing by-pass ratio will change the shape and weight of the duct that uplift encourages them to continue research in this field. Innumerable studies related to S-shaped duct have proven that its performance depends on many factors like curvature, upstream compressor’s vortices, swirl, insertion of struts, geometrical aspects, Mach number and many more. The application of flow control devices, wall shape optimization techniques, and integrated concepts lead a better system performance and shorten the duct length.  This review paper is an endeavor to encapsulate all the above aspects and finally, it can be concluded that the intermediate duct is a key component to keep the overall weight and specific fuel consumption low. The shape and curvature of the duct significantly affect the pressure distortion. The wall static pressure distribution along the inner wall significantly higher than that of the outer wall. Duct pressure loss enhances with the aggressive design of duct, incursion of struts, thick inlet boundary layer and higher swirl at the inlet. Thus, one should focus on research areas for better aerodynamic effects of the above parameters which give duct design with optimum pressure loss and non-uniformity within the duct.

scholarly journals Redesign of a High-Pressure Compressor Blade Accounting for Nonlinear Structural Interactions

2014 ◽  
Author(s):  
Alain Batailly ◽  
Mathias Legrand ◽  
Antoine Millecamps ◽  
Sèbastien Cochon ◽  
François Garcin
Keyword(s):  
High Pressure ◽  
Forced Response ◽  
Compressor Blade ◽  
Design Stage ◽  
Blade Design ◽  
Early Integration ◽  
Nonlinear Structural ◽  
High Pressure Compressor ◽  
Structural Interactions ◽  
Pressure Compressor

Recent numerical developments dedicated to the simulation of rotor/stator interaction involving direct structural contacts have been integrated within the Snecma industrial environment. This paper presents the first attempt to benefit from these developments and account for structural blade/casing contacts at the design stage of a high-pressure compressor blade. The blade of interest underwent structural divergence after blade/abradable coating contact occurrences on a rig test. The design improvements were carried out in several steps with significant modifications of the blade stacking law while maintaining aerodynamic performance of the original blade design. After a brief presentation of the proposed design strategy, basic concepts associated with the design variations are recalled. The iterated profiles are then numerically investigated and compared with respect to key structural criteria such as: (1) their mass, (2) the residual stresses stemming from centrifugal stiffening, (3) the vibratory level under aerodynamic forced response and (4) the vibratory levels when unilateral contact occurs. Significant improvements of the final blade design are found: the need for an early integration of nonlinear structural interactions criteria in the design stage of modern aircraft engines components is highlighted.

A Machine Learning Based Approach of Performance Estimation for High-Pressure Compressor Airfoils

2018 ◽  
Author(s):  
Jonas Marx ◽  
Stefan Gantner ◽  
Jörn Städing ◽  
Jens Friedrichs
Keyword(s):  
Machine Learning ◽  
High Pressure ◽  
Machine Learning Algorithms ◽  
Performance Estimation ◽  
Predictive Maintenance ◽  
Support Vector ◽  
K Nearest Neighbor ◽  
Operating Characteristics ◽  
High Pressure Compressor ◽  
Pressure Compressor

In recent years, the demands of Maintenance, Repair and Overhaul (MRO) customers to provide resource-efficient after market services have grown increasingly. One way to meet these requirements is by making use of predictive maintenance methods. These are ideas that involve the derivation of workscoping guidance by assessing and processing previously unused or undocumented service data. In this context a novel approach on predictive maintenance is presented in form of a performance-based classification method for high pressure compressor (HPC) airfoils. The procedure features machine learning algorithms that establish a relation between the airfoil geometry and the associated aerodynamic behavior and is hereby able to divide individual operating characteristics into a finite number of distinct aero-classes. By this means the introduced method not only provides a fast and simple way to assess piece part performance through geometrical data, but also facilitates the consideration of stage matching (axial as well as circumferential) in a simplified manner. It thus serves as prerequisite for an improved customary HPC performance workscope as well as for an automated optimization process for compressor buildup with used or repaired material that would be applicable in an MRO environment. The methods of machine learning that are used in the present work enable the formation of distinct groups of similar aero-performance by unsupervised (step 1) and supervised learning (step 2). The application of the overall classification procedure is shown exemplary on an artificially generated dataset based on real characteristics of a front and a rear rotor of a 10-stage axial compressor that contains both geometry as well as aerodynamic information. In step 1 of the investigation only the aerodynamic quantities in terms of multivariate functional data are used in order to benchmark different clustering algorithms and generate a foundation for a geometry-based aero-classification. Corresponding classifiers are created in step 2 by means of both, the k Nearest Neighbor and the linear Support Vector Machine algorithms. The methods’ fidelities are brought to the test with the attempt to recover the aero-based similarity classes solely by using normalized and reduced geometry data. This results in high classification probabilities of up to 96 % which is proven by using stratified k-fold cross-validation.

Flow Measurements in a Nozzle Guide Vane Passage With a Low Aspect Ratio and Endwall Contouring

2000 ◽  
Author(s):  
Steven W. Burd ◽  
Terrence W. Simon
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Guide Vane ◽  
Flow Measurements ◽  
Vast Number ◽  
Aspect Ratios ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

The vast number of turbine cascade studies in the literature has been performed in straight-endwall, high-aspect-ratio, linear cascades. As a result, there has been little appreciation for the role of, and added complexity imposed by, reduced aspect ratios. There also has been little documentation of endwall profiling at these reduced spans. To examine the role of these factors on cascade hydrodynamics, a large-scale nozzle guide vane simulator was constructed at the Heat Transfer Laboratory of the University of Minnesota. This cascade is comprised of three airfoils between one contoured and one flat endwall. The geometries of the airfoils and endwalls, as well as the experimental conditions in the simulator, are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow field in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indicate that the acceleration imposed by endwall contouring and airfoil turning is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significantly from that adjacent to the straight endwall.

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