bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation Study on the Work Characteristics of Combined Diesel-Electric and Gas Turbine (CODLAG)
Authors: Wang Zhitao , Li Jian , Li Tielei , Wang Weitian , Li Shuying 
Published: August 2018

The combined diesel-electric and gas turbine (CODLAG) plant is a new type of ship power plant combining the advantages of electric propulsion system and mechanical propulsion system. The requires about ship power grid is lower than full electric propulsion mode, at the same time it can gain the quiet of electric propulsion in the low working conditions and increase the mobility of the ship in the high working conditions. Unlike traditional mechanical propulsion methods and forward-looking all-electric propulsion methods, the CODLAG plant has a coupling between mechanical propulsion and electric propulsion mode. The cooperative working characteristics of two different nature systems is still need further research.
For the in-depth research of CODLAG device’s characters, this study built a simulation model of CODLAG device based on Matlab/Simulink and C/C++ platform. A kind of torque-shaft speed double closed-loop control strategy based on PID was used on the CODLAG device. And the typical work condition of CODLAG, including merging, merging off and variable work condition, was simulated in this study.
Through the simulation, the dynamic response of main parameters at typical condition have been got. Then, characters of CODLAG device with CPP was simulated at variable condition. And the thrust response was compared with FPP’s. Through comparative analysis, the effectiveness of integrated simulation method specifying to CODLAG device was verified, and some useful conference was provided for the future research.
The Mechanism of the Flow in the Hub Corner and the Control by Tailing Edge Gaps
Authors: Zhao Wenfeng , Jiang Bin , Duan Yu , Tian Zhitao , Zheng Qun 
Published: August 2018

High-pressure ratio is one of the important characteristics of the sustainable development of the modern aero-engine compressor components. When the fluid flows through the compressor cascade row, it will be influenced by both the streamwise pressure gradient and the transverse pressure gradient, which will cause hub-corner separation or stall. In this paper, different diffusion factors are chosen for the cascades. Each diffusion factor has different turning angles. The formation mechanism of hub-corner separation is studied under the condition of zero angle of attack. Numerical simulation is used to study the influence of pressure gradient on the flow field in the corner. The scale of the concentrated shed vortex forms in the suction surface increases with the increasing of the transverse pressure gradient during the hub-corner separation. When the streamwise pressure gradient increases, the suction surface vortex forms the corner stall. By reasonable design, the two vortexes can cancel out each other. At this time, the loss of cascades is the minimum.
Based on the flow mechanism of the corner separation/stall, the trailing gaps are set on three typical turn angle cascades. The results show that the trailing gaps can control the radial development of the suction surface vortex during the stall and improve flow field. The jet cannot blow the suction side boundary layer away during the corner separation, because the gap does not change the static pressure distribution at the root of the cascade. In a word, the trailing edge gaps can not only inhibit the separation in the hub corner but also have the minimum leakage loss at design point. It can be used as an effective and practical compressor design method.
Design Optimization of Heat Exchangers for Aero Engines With the Use of a Surrogate Model Incorporating Performance Characteristics and Geometrical Constraints
Authors: Salpingidou Christina , Misirlis Dimitrios , Vlahostergios Zinon , Flouros Michael , Donus Fabian , Yakinthos Kyros 
Published: August 2018

The present work is focused on the optimization of the performance characteristics of a recuperator specifically designed for aero engine applications, targeting the reduction of specific fuel consumption and taking into consideration aero engine geometrical constraints and limitations. The recuperator design was based on the elliptically profiled tubular heat exchanger which was developed and invented by MTU Aero Engines AG. For the specific fuel consumption investigations the Intercooled Recuperated Aero engine cycle, combining both intercooling and recuperation, was considered.
The optimization was performed with the development of a recuperator surrogate model, capable to incorporate major recuperator geometrical features. A large number of recuperator design scenarios was assessed, in which additional design criteria and constraints were applied. Thus, a significantly large recuperator design space was covered resulting to the identification of feasible recuperator designs providing beneficial effect on the Intercooled Recuperated Aero engine leading to reduced specific fuel consumption and weight.
An Advanced Surge Dynamic Model for Simulating ESD Events and Comparing Different Anti-Surge Strategies
Authors: Munari Enrico , Morini Mirko , Pinelli Michele , Brun Klaus , Simons Sarah , Kurz Rainer , Moore Jeffrey 
Published: August 2018

Despite advancements in research and industry, compressors still have to operate in the stable region of the characteristic curves otherwise, at low flow ranges, they enter an unstable regime. The worst instability that can arise in industrial compressors is called surge, which involves the whole system in view of the fact that it generates dangerous pressure and mass flow fluctuations. Thus, this phenomenon has to be prevented since it implies the deterioration of performance and leads to mechanical damage to the compressor and system components.
It is clear that, currently, compression system models have a crucial role in predicting the phenomena which can occur in the compressor and pipelines during operation.
In this paper, a dynamic model, developed in the Matlab/Simulink environment, is further implemented to allow the study of surge events caused by rapid transients, such as emergency shutdown events (ESD). The aim is to validate the experimental data obtained in a single stage centrifugal compressor installed in the test facility at Southwest Research Institute. The test facility consists of a closed loop system and is characterized by a recycling circuit, and thus a recycling valve, which is opened in case of surge or driver shutdown. In this work, the recycling circuit is implemented in the model as well, and comparisons between recorded data and simulations were carried out. Moreover, different actions for recovering/preventing surge are simulated by controlling different valves along the piping system and by adding a check valve immediately downstream the compressor.
The results demonstrated the fidelity of the model and its capability of simulating piping systems with different configurations and components, also showing, qualitatively, the different effects of some alternative actions which can be taken after surge onset.
Stall and Surge in Wet Compression: Test Rig Development and Experimental Results
Authors: Munari Enrico , D’Elia Gianluca , Morini Mirko , Pinelli Michele , Spina Pier Ruggero 
Published: August 2018

Wet compression is a strategy adopted to increase the power output of gas turbines, with respect to dry conditions, usually also incrementing the operating range of the compressor. However, stall and surge are two aerodynamic instabilities which depend on many factors, and they are expected to occur even in wet compression at low flow rates. Despite the many studies carried out in the last 80 years, literature does not offer many works concerning these instability phenomena in wet compression. In this paper, an experimental analysis of stall and surge in wet compression conditions is carried out on an axial-centrifugal compressor installed in an existing test rig at the Engineering Department of the University of Ferrara. Some modifications of the test rig were necessary.
The intake duct was implemented with a water injection system which, by means of water spray injectors, allows the uniform mixing of air and water before the compressor inlet. The control and data acquisition system of the test bench was updated with new hardware and software to obtain faster data sampling. Transient and steady-state tests were carried out to make a comparison with the experimental results in dry conditions. The analysis was carried out using traditional thermodynamic sensors, by means of both classic post-processing techniques, and cyclostationary analysis.
The aim is to i) evaluate the influence of wet compression on the stable performance of the compressor ii) qualitatively identify the characteristics of stall and surge in wet compression by means of sensors which were shown to capture these phenomena well and iii) demonstrate the reliability of cyclostationary analysis in wet compression conditions for stall and surge analysis.
Adaptive Preliminary-Design Workflow for Aero Engine Secondary Air System Cavities With an Application Case of Windage and Heat Transfer in a Rotor-Stator Cavity With Axial Through Flow
Authors: Wildow Toni , Dengg Hubert , Höschler Klaus , Sommerfeld Jonathan 
Published: August 2018

At the preliminary design stage of the engine design process, the behaviour and efficiency of different engine designs are investigated and evaluated in order to find a best matching design for a set of engine objectives and requirements. The prediction of critical part temperatures as well as the reduction of the uncertainty of these predictions is decisive to bid a competitive technology in aerospace technology. Automated workflows and Design of Experiments (DOE) are widely used to investigate large number of designs and to find an optimized solution. Nowadays, technological progress in computational power as well as new strategies for data handling and management enables the implementation of large DOEs and multi-objective optimizations in less time, which also allows the consideration of more detailed investigations in early design stages.
This paper describes an approach for a preliminary-design workflow that implements adaptive modelling and evaluation methods for cavities in the secondary air system (SAS). The starting point for the workflow is a parametric geometry model defining the rotating and static components. The flow network within the SAS is automatically recognized and CFD and Thermal-FE models are automatically generated using a library of generic models. Adaptive evaluation algorithms are developed and used to predict values for structural, air system and thermal behaviour. Furthermore, these models and evaluation techniques can be implemented in a DOE to investigate the impact of design parameters on the predicted values. The findings from the automated studies can be used to enhance the boundary conditions of actual design models in later design stages.
A design investigation on a rotor-stator cavity with axial through flow has been undertaken using the proposed workflow to extract windage, flow field and heat transfer information from adiabatic CFD calculations for use in thermal modelling. A DOE has been set up to conduct a sensitivity analysis of the flow field properties and to identify the impact of the design parameters. Additionally, impacts on the distribution of the flow field parameters along the rotating surface are recognized, which offers a better prediction for local effects in the thermal FE model.
Structural Analysis of Profiled Tubes for a Turbofan Engine Supercritical-CO2 Bottoming Cycle Heat Exchanger
Authors: Rengel Jon , Jacob Florian , Rolt Andrew , Sethi Vishal 
Published: August 2018

The EU Horizon 2020 ULTIMATE project aims to mitigate one of the greatest loss sources in modern turbofans: the heat in core exhaust gases. The introduction of a closed-circuit recuperated bottoming cycle, using supercritical CO2 (S-CO2) as a working fluid that is heated by the exhaust gases, has been shown to be a feasible option.
Involute spiral heat exchangers have been studied for intercoolers and cooled cooling air systems. However, placing them in the core exhaust and using S-CO2 implies significant mechanical design challenges from the elevated temperatures and high internal pressures. The studied scenario considers a heat exchanger of 60% effectiveness, with an internal fluid pressure of 32 MPa. The primary objective is to minimise the total mass of the heat exchanger tubes.
The work is focused on studying elliptical tubes and an alternative multi-arc cross-section design with internal webs that is more structurally efficient. A parametric analysis of the proposed geometry has been conducted to capture the influence of each of the geometric variables on the resulting stresses.
The alloy Ti-6Al-4V is selected as the tube material and the results show that for a 400 MPa maximum allowable stress, a chord of 10 mm, a chord to thickness ratio of eight and a mi nimum wall thickness of 0.2 mm, the minimum tube weight is 20.5 g/m.
LES and RANS Analysis of the End-Wall Flow in a Linear LPT Cascade: Part I — Flow and Secondary Vorticity Fields Under Varying Inlet Condition
Authors: Pichler R. , Zhao Yaomin , Sandberg R. D. , Michelassi V. , Pacciani R. , Marconcini M. , Arnone A. 
Published: August 2018

In low-pressure-turbines (LPT) around 60–70% of losses are generated away from end-walls, while the remaining 30–40% is controlled by the interaction of the blade profile with the end-wall boundary layer. Experimental and numerical studies have shown how the strength and penetration of the secondary flow depends on the characteristics of the incoming end-wall boundary layer. Experimental techniques did shed light on the mechanism that controls the growth of the secondary vortices, and scale-resolving CFD allowed to dive deep into the details of the vorticity generation. Along these lines, this paper discusses the end-wall flow characteristics of the T106 LPT profile at Re = 120K and M = 0.59 by benchmarking with experiments and investigating the impact of the incoming boundary layer state. The simulations are carried out with proven Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulation (LES) solvers to determine if Reynolds Averaged models can capture the relevant flow details with enough accuracy to drive the design of this flow region.
Part I of the paper focuses on the critical grid needs to ensure accurate LES, and on the analysis of the overall time averaged flow field and comparison between RANS, LES and measurements when available. In particular, the growth of secondary flow features, the trace and strength of the secondary vortex system, its impact on the blade load variation along the span and end-wall flow visualizations are analysed. The ability of LES and RANS to accurately predict the secondary flows is discussed together with the implications this has on design.
Reduction of Burner Variants for Differing Fuel Compositions by Combining Intelligent Control Methods and Experimental Data of Siemens SGT-400 Dry Low Emission Combustion System
Authors: Hubbard Phill , Liu Kexin , Sadasivuni Suresh , Bulat Ghenadie 
Published: August 2018

Extension of gas fuel flexibility of a current production standard SGT-400 industrial gas turbine combustor is reported in this paper.
A successful development program has increased the capability of the standard production dry low emissions burner configuration to burn a range of fuels covering a temperature corrected wobbe index from 30 to 49 MJ/m3. A standard SGT-400 13.4 MW dry low emission double skinned combustor can was tested with a standard production gas burner for a cannular combustion system. Emissions, combustion dynamics, fuel pressure and flashback monitoring via measurement of burner metal temperatures, were the main parameters used to evaluate the impact of fuel flexibility on combustor performance. High pressure rig tests were carried out to demonstrate the capabilities of the combustion system at engine operating conditions across a wide range of ambient conditions. Variations of the fuel heating value were achieved by blending natural gas with CO2 as diluent.
The standard SGT-400 combustion system employs proven dry low emissions technology for natural gas and liquid fuels such as diesel within a specified range of fuel heating values. With the aid of novel intelligent control software, the gas fuel capability of the SGT-400 standard dry low emissions burner has been extended, with the engine, achieving stable operation and reduced emissions across the load range despite variations of the composition of the fuel supply. This, combined with previous experience from high pressure rig and engine testing of the different burner configurations that covered this range, resulted in a reduction in the number of hardware configurations from three burners to two. Testing showed that the standard production burner can reliably operate with a fuel temperature controlled wobbe index as low as 30 MJ/m3 which corresponds to 20% CO2 (by volume) in the fuel.
The performance of four different fuels with heating values in terms of temperature controlled wobbe index: 30, 33, 35 and 45 MJ/m3 (natural gas), is presented for the current production hardware. Test results show that NOx emissions decrease as the fuel heating value is reduced. Also note that a decreasing temperature controlled wobbe index leads to a requirement to increase the fuel supply pressure. The tests results obtained on the Siemens SGT-400 combustion system provide significant improvement for industrial gas turbine burner design for fuel flexibility.
Numerical Study on Deformation of Gland Seal Housing at LP Ends on a Nuclear Steam Turbine
Authors: Guo Yanan , Xie Danmei , Huang Xiangjun , Zheng Huabing , Mei Ziyue , Zhang Hengliang 
Published: August 2018

The rubbing between static and moving parts of steam turbine is one of the frequent faults and difficult to diagnose accurately. In the high-speed rotation of steam turbine, if the clearance between the static and moving parts is too small, there is a possibility of rubbing accident, especially for the ends of LP steam turbine in a nuclear power plant, which will affect the safety operation of the steam turbine.
In this paper, the gland seal housing deformation of LP casing in 1000MW nuclear steam turbine is calculated and analyzed. Based on ProE and ANSYS/Workbench software, the 3D geometry model and the finite element mathematical model of LP inner casing of nuclear steam turbine are established, and the boundary conditions are determined at first. Secondly, the deformation of the gland seal housing at the LP casing end is calculated and analyzed under different conditions. Thirdly, the influence of different components temperature rise on the deformation of gland seal housing is analyzed.
Twin-Web Turbine Discs: Part 2 — Fabrication and Processing
Authors: Vasilyev Boris , Magerramova Liubov , Salnikov Anton , Tsykunov Nikolay , Isakov Vladimir , Semenov Artem 
Published: August 2018

The first part of this paper shows that the implementation of twin-web (hollow) discs can lead to an 8–30% decrease in mass or to a cyclic life increase of up to 300%, depending on the size of the disc and the operating conditions. The second part of this paper describes the results of the development of approaches for the manufacturing and processing of twin-web discs, both with the help of additive and traditional manufacturing methods. Several hollow discs with a closed cavity and a slot in the hub are made from the heat-resistant nickel alloy EI698P with the help of additive manufacturing (AM) and hot isostatic pressing (HIP), respectively. Various welding methods are considered for the production of the twin-web discs.
The effect of post-processing on the characteristics of the materials is investigated in specimens that were produced with AM methods. Special attention is paid to the surface treatment methods that should be used for discs manufactured by AM methods. The “printed” discs were controlled using radiographic, ultrasonic, fluorescent penetrant, and eddy current methods, and they were examined using computed tomography.
As a result, this paper shows that different approaches can be used for the manufacturing and processing of twin-web discs.
Unsteady Flow Simulation of Buoyancy-Driven Flows in High-Pressure Compressor Disk Cavities
Authors: Tateishi Atsushi , Watanabe Toshinori , Himeno Takehiro 
Published: August 2018

This paper focuses on the buoyancy-induced unsteady flow phenomenon inside high-pressure compressor disk cavities. In order to understand the flow structure in a realistic configuration, a 10-stage core compressor of the NASA/GE Energy Efficient Engine is adopted as a computational target. The numerical flow simulation is conducted on a full annulus model, where the temperature distribution on the wall is modeled based on the core test results. The time-averaged flow fields are obtained by detached eddy simulation (DES) and two-dimensional axisymmetric Reynolds-averaged Navier-Stokes (RANS) simulation, and the difference is discussed in detail.
The DES result showed large-scale, vortical structures with significant radial velocity fluctuations especially in the rear part of the compressor. These fluctuations create radial arm-like structure in the temperature distribution in the cavity, and greatly enhance the mixing between the bore coolant and hot air near the cavity wall. In addition, it is observed that the hot air discharged from the cavities creates a large cell at bore region, which extends across several rear stages.
Although the present study successfully illustrates the entire structure of unsteady flow in heated compressor disk cavities including full stages, a more detailed validation will be needed to further confirm the applicability of DES for the targeted flow.
Representation and Analysis of Geometric Uncertainties in Rotor Blades
Authors: Carassale Luigi , Bruzzone Silvia , Cavicchi Andrea , Marrè Brunenghi Michela 
Published: August 2018

Geometric uncertainties involved in the rotor blade manufacturing process are a major concern for designers. The deviation of the produced components from their nominal geometry have an impact on the Natural Frequencies (NF) that, under certain circumstances, may have negative effects on the dynamic forced response in operative conditions.
Geometric defects are usually limited by imposing dimensional tolerances based on empirical considerations, simplified approach that may lead to costly manufacturing requirements that still may not guarantee safe results.
This paper proposes a probabilistic representation of the geometric uncertainties for rotor blades and defines a procedure to evaluate their effects on the blade NFs. The deviation from nominal geometry is represented through the Principal Component Analysis (PCA) where it is expressed as a sum of characteristic geometric shapes (GUMs) modulated by mutually uncorrelated random variables (Principal Components, PC). The effect of each GUM is then linearly propagated on the blade NFs and a sensitivity matrix is finally defined.
The procedure is applied to a case-study that concerns a set of 50 nominally identical compressor blades and the ability of GUMs to represent the effects of geometric uncertainties is tested.