Flow Interactions in Low Bypass Ratio Multi-Spool Turbofan Engines

2019 ◽  
Author(s):  
Vishwas Verma ◽  
Gursharanjit Singh ◽  
A. M. Pradeep
Keyword(s):  
Flow Pattern ◽  
System Modeling ◽  
Three Dimensional ◽  
Integrated System ◽  
Operating Conditions ◽  
System Level ◽  
Component Level ◽  
Turbofan Engines ◽  
Flow Interactions ◽  
Marginal Values

Abstract Multi-spool compression systems are characterized by two or more compressor stages running at different rotational speeds. The response of an individual component can be different from an integrated system. Limiting operating conditions such as choke and stall points could have substantially different effects. The present paper explores the interactions and coupling significance between different stages of a multi-spool compression system. Further, an attempt is made by modifying the shape of the inter-compressor duct (ICD) to improve the system performance. The multi-spool system in this study comprises of the NASA stage 67 as the fan followed by in-house core and bypass ducts and a single stage booster. It is observed that the flow pattern in an ICD is entirely different in stand-alone modeling than in the integrated system modeling, owing to fan wakes and booster upstream influences. The booster performance is dependent on the duct exit flow pattern. The shape of the baseline ICD is tailored to reduce extra losses which is generated due to reduction in the length of the ICD and hence making the system more compact. It is shown that the shape tailoring optimization of ICD done independently result in a significant improvement in the duct exit flow pattern and hence an improvement in the booster performance. However, this gain in the performance is reduced to marginal values for an integrated system. This happens due to a strong coupling of the ICD flow pattern with the fan wakes and highly three dimensional nature of the ICD flow pattern. Therefore, it is found that component level optimization may not give rise to an equivalent system-level improvement.

Research on Intelligent MCAD/CAPP/CAFD Integrated System Modeling

2011 ◽  
Vol 48-49 ◽  
pp. 960-963
Author(s):  
Hui Fang Chen
Keyword(s):  
Structural Design ◽  
System Modeling ◽  
Functional Model ◽  
Three Dimensional ◽  
Integrated System ◽  
Case Based Reasoning ◽  
Planning Techniques ◽  
Object Oriented Technology ◽  
Mapping Process ◽  
Feature Based

Feature extraction and expression of three-dimensional MCAD entity model is independent of platform. According to STEP, this paper discusses for a unified MCAD / CAPP / CAFD integrated system to establish the program model and study the key technologies. The STEP neutral file that contains the model is taken to decide the design features of the part. The identification of geometric features and geometric characteristics of features to the mapping process, rule-based reasoning and case-based reasoning with the way things feature-based process planning techniques in the process of reasoning problems. UML object-oriented technology and methods such as functional analysis of the system and structural design, the initial mode of integrated system functional model and structure is established

Electro-Thermal Simulation of Interconnected Systems at Transient Operating Conditions

2017 ◽  
Author(s):  
Torsten Hauck ◽  
Vibhash Jha ◽  
J. H. J. Janssen
Keyword(s):  
Order Reduction ◽  
Element Model ◽  
Operating Conditions ◽  
System Level ◽  
Large Set ◽  
Component Level ◽  
Model Order ◽  
Design And Optimization ◽  
Efficient Simulation ◽  
Current State

The development of complex electronic modules requires very efficient simulation technique for faster design and optimization process. For smaller component level models, current state of the art FEM/CFD tools is sufficient if appropriate boundary conditions are used. But for larger system level models, this approach can be computationally expensive as the finite element model can lead to very large set of equations. Hence, there is a need for much efficient computational methods such as model order reduction (MOR). MOR was developed to study property of dynamical systems to reduce their complexity without changing input/output to the system.

Dynamic Characterization of Tilting Pad Journal Bearings From Component and System Level Testing

2012 ◽  
Author(s):  
Adolfo Delgado ◽  
Mirko Librashi ◽  
Giuseppe Vannini
Keyword(s):  
Stability Analysis ◽  
High Speed ◽  
Dynamic Stiffness ◽  
Operating Conditions ◽  
Logarithmic Decrement ◽  
Experimental Results ◽  
System Level ◽  
Component Level ◽  
Force Coefficients ◽  
Tilting Pad

The dynamic response of a direct lube, 5-pad, rocker-back pivot tilting pad bearing is characterized in a controlled motion (component level) test rig, and in a spin bunker (full system level) using a dummy rotor mounted on two identical bearings. In the component level test, the force coefficients (stiffness, damping, mass) are identified from pseudorandom excitations using a 2-DOF model. N-DOF system including the pad motions has been shown to yield frequency dependent coefficients that warrant the use of asynchronous coefficients for stability analysis in centrifugal compressors. However, experimental results showed that the real part of the dynamic stiffness is well represented as a constant stiffness and mass coefficients while the imaginary part yields a constant damping coefficient (i.e. frequency independent). In the system level test, a dedicated dummy rotor (representative of a high speed centrifugal compressor rotor) is excited by a magnetic shaker throughout a frequency range covering the rotor modes of interest while spinning at constant speed. From the rotor harmonic response the damping of each mode is extracted using a curve-fitting method based on a 1-DOF model for a given set of speeds. The dummy rotor test provides reference values for system logarithmic decrement and further validates the component level test results. The logarithmic decrement prediction using identified bearing force coefficients are in good agreement with the experimental results. In addition, using for prediction identified coefficients in a classical K-C-M or synchronous K-C form yields similar results (within 15%). This indicates that for the given bearing geometry (clearance, offset and size) and operating conditions, synchronously reduced force coefficients are adequate for stability analysis. Comparison of the identified force coefficients with results from commercially available code yielded reasonable agreement on direct coefficients while some discrepancies are highlighted on the cross-coupled coefficients.

Integrated Real-Time Event Based Cost Modeling of Battery Manufacturing System

2014 ◽  
Author(s):  
Yang Li ◽  
Qing Chang
Keyword(s):  
Real Time ◽  
Manufacturing System ◽  
System Modeling ◽  
Integrated System ◽  
Cost Modeling ◽  
System Level ◽  
System Level Modeling ◽  
Event Based ◽  
Unified Index

Information of battery manufacturing system is becoming increasingly transparent, detailed and real-time. Despite the big potential in improving productivity, the advantages of information are not fully realized due to a lack of system level modeling. Motivated by this need, we develop an integrated system modeling approach to quantify the systematic impact of stations and supporting activities with a unified index called event based cost (EBC). The analysis provides a severity ranking of stations and supporting activities. A case study is conducted to demonstrate the application of the model in a battery production system and its ability to facilitate decision making.

Secondary Flows and Vortex Motion in a High-Efficiency Backswept Impeller at Design and Off-Design Conditions

1990 ◽  
Vol 112 (1) ◽  
pp. 7-13 ◽  
Author(s):  
C. Hah ◽  
H. Krain
Keyword(s):  
Flow Pattern ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Vortex Motion ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Optimum Shape ◽  
Discharge Velocity

The three-dimensional viscous flow field of a 4.7:1 pressure ratio backswept impeller was studied experimentally and numerically by using laser velocimetry and an advanced three-dimensional viscous code. The impeller was designed by a CAD method, and a maximum rotor efficiency of 94 percent was achieved. Both the experimental and the theoretical approach revealed comparatively smooth impeller discharge velocity profiles at all three operating conditions (design, choke, and near surge) differing widely from the well-known jet/wake-type flow pattern. The three-dimensional viscous code was used for detailed flowfield studies, i.e., secondary flows; vortex motion and tip-clearance effects were analyzed at design and off-design conditions. The comparison of experimental and numerical results indicates that the tip-clearance effect should be properly modeled to predict the impeller flow pattern properly and that optimum shape of rotor exit flow pattern can be obtained by controlling the swirling vortex motion.

Dynamic Infrared System Level Fault Isolation

2003 ◽  
Author(s):  
John A. Naoum ◽  
Johan Rahardjo ◽  
Yitages Taffese ◽  
Marie Chagny ◽  
Jeff Birdsley ◽  
...  
Keyword(s):  
Fault Isolation ◽  
System Level ◽  
System Component ◽  
Component Level ◽  
Ir Imaging ◽  
Non Destructive

Abstract The use of Dynamic Infrared (IR) Imaging is presented as a novel, valuable and non-destructive approach for the analysis and isolation of failures at a system/component level.

scholarly journals Intelligent long-term performance analysis in power electronics systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saeed Peyghami ◽  
Tomislav Dragicevic ◽  
Frede Blaabjerg
Keyword(s):  
Performance Indicator ◽  
Thermal Characteristics ◽  
Operating Conditions ◽  
System Level ◽  
Power Electronic ◽  
Reliability Modeling ◽  
Artificial Neural Network Ann ◽  
Long Term Performance ◽  
Term Performance

AbstractThis paper proposes a long-term performance indicator for power electronic converters based on their reliability. The converter reliability is represented by the proposed constant lifetime curves, which have been developed using Artificial Neural Network (ANN) under different operating conditions. Unlike the state-of-the-art theoretical reliability modeling approaches, which employ detailed electro-thermal characteristics and lifetime models of converter components, the proposed method provides a nonparametric surrogate model of the converter based on limited non-linear data from theoretical reliability analysis. The proposed approach can quickly predict the converter lifetime under given operating conditions without a further need for extended, time-consuming electro-thermal analysis. Moreover, the proposed lifetime curves can present the long-term performance of converters facilitating optimal system-level design for reliability, reliable operation and maintenance planning in power electronic systems. Numerical case studies evaluate the effectiveness of the proposed reliability modeling approach.

Advances in coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery

2020 ◽  
pp. 095441002096645
Author(s):  
Jie Gao ◽  
Chunde Tao ◽  
Dongchen Huo ◽  
Guojie Wang
Keyword(s):  
Performance Improvement ◽  
High Efficiency ◽  
Three Dimensional ◽  
Great Influence ◽  
Aerodynamic Characteristics ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Axial Turbine ◽  
Flow Interactions ◽  
And Performance

Marine, industrial, turboprop and turboshaft gas turbine engines use nonaxisymmetric exhaust volutes for flow diffusion and pressure recovery. These processes result in a three-dimensional complex turbulent flow in the exhaust volute. The flows in the axial turbine and nonaxisymmetric exhaust volute are closely coupled and inherently unsteady, and they have a great influence on the turbine and exhaust aerodynamic characteristics. Therefore, it is very necessary to carry out research on coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics, so as to provide reference for the high-efficiency turbine-volute designs. This paper summarizes and analyzes the recent advances in the field of coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery. This review covers the following topics that are important for turbine and volute coupled designs: (1) flow and loss characteristics of nonaxisymmetric exhaust volutes, (2) flow interactions between axial turbine and nonaxisymmetric exhaust volute, (3) improvement of turbine and volute performance within spatial limitations and (4) research methods of coupled turbine and exhaust volute aerodynamics. The emphasis is placed on the turbine-volute interactions and performance improvement. We also present our own insights regarding the current research trends and the prospects for future developments.

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