bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Throttle Loss Recovery Concept Using an Expander for a 2.0 Litre Turbocharged Gasoline Engine
Authors: Lu P. , Hu B. , Brace C. 
Published: August 2015

In the internal combustion engine, a large amount of energy is rejected in the form of exhaust heat without being converted into brake work.
Additionally, in gasoline engines, throttle losses are also a considerable disadvantage limiting the capability to achieve higher thermal efficiency. Under part load conditions, both the power demand and engine speed are much lower than the maximum achievable. The throttle is partially closed to restrict inlet air mass flow to regulate the brake power production. To overcome the friction and turbulence losses at the small throttle opening, negative pressure is produced in the manifold at the cost of engine power.
This paper explores the effectiveness of an expander installed in the inlet duct of the engine to lessen, even eliminate, the throttle losses by allowing power to be reclaimed from the pressure drop across the expander, which will otherwise be wastefully dissipated across the throttle. In this way the pumping losses are reduced.
The engine system was modelled in GT-Power which is a 1-dimensional engine simulation code. The limits in decreasing in pressure drop through the throttle and the power generation from the expander were explored. Together with a turbo machine recovering energy from the exhaust flow, this system was able to enhance the fuel economy by about 5% when operating at 1.75 bar BMEP from 500–3000rpm compared with a conventional turbocharged engine. The influence of the expander machinery on the combustion and the turbocharger performance was also discussed. To achieve the highest performance level, careful optimization of the expander size and control strategy and proper matching with engine system are critical.
Undergraduate Project in Compressor Rig Design, Fabrication and Testing for Complete Engineering Training
Authors: Vo Huu Duc , Trépanier Jean-Yves 
Published: August 2015

An ambitious project in propulsion was introduced as part of the final-year integrator project offerings of the mechanical and aerospace engineering programs at École Polytechnique de Montréal in 2011–2012. It has been running successfully for the past three academic years. The project consists in the design, fabrication and placement into service of a functional instrumented multi-stage compressor test rig, including the compressor, for research in compressor aerodynamics. A team of 15–17 senior-year undergraduate engineering students are given set of design and performance specifications and measurement requirements, an electric motor and drive, a data acquisition system and some measurement probes. They must complete the project in two semesters with a budget on the order of Can$15,000. The compressor is made from rapid prototyping to keep production cost and time reasonable. However, its required rotation speed of 7200 rpm stretches the limits of the plastic material and presents the same structural challenges as industrial compressors running at higher speeds.
The students are split into sub-teams according to the required disciplines, namely compressor aerodynamics, general aerodynamics, structures, dynamics, mechanical design and integration, instrumentation and project management. For the initial phase, which covers the first two months, the students receive short seminars from experts in academia and industry in each discipline and use the knowledge from fundamental engineering courses to analytically model the different components to come up with a preliminary design. In the second phase, covering months three through six, the students are trained at commercial simulation tools and use them for detailed analysis to refine and finalize the design. In each of the first two phases, the students present their work in design reviews with a jury made up of engineers from industry and supervising professors. During the final phase, the compressor is built and tested with data acquisition and motor control programs written by the students. Finally, the students present their results with comparison of measured performance with numerical and analytical predictions from the first two phases and hand over their compressor rig with design and test reports as well as a user manual and an assembly/maintenance manual.
This complete project allows the students to put into practice virtually all the courses of their undergraduate engineering curriculum while giving them an extensive taste of the rich and intellectually challenging environment of gas turbine and turbomachinery engineering.
Advanced Water Droplet Erosion Protection for Modern Low Pressure Steam Turbine Steel Blades
Authors: Schuerhoff Joerg , Ghicov Andrei , Sattler Karsten 
Published: August 2015

Blades for low pressure steam turbines operate in flows of saturated steam containing water droplets. The water droplets can impact rotating last stage blades mainly on the leading edge suction sides with relative velocities up to several hundred meters per second. Especially on large blades the high impact energy of the droplets can lead to a material loss particularly at the inlet edges close to the blade tips. This effect is well known as “water droplet erosion”.
The steam turbine manufacturer use several techniques, like welding or brazing of inlays made of erosion resistant materials to reduce the material loss. Selective, local hardening of the blade leading edges is the preferred solution for new apparatus Siemens steam turbines. A high protection effect combined with high process stability can be ensured with this Siemens hardening technique. Furthermore the heat input and therewith the geometrical change potential is relatively low. The process is flexible and can be adapted to different blade sizes and the required size of the hardened zones. Siemens collected many years of positive operational experience with this protection measure.
State of the art turbine blades often have to be developed with precipitation hardening steels and/or a shroud design to fulfill the high operational requirements. A controlled hardening of the inlet edges of such steam turbine blades is difficult if not impossible with conventional methods like flame hardening. The Siemens steam turbine factory in Muelheim, Germany installed a fully automated laser treatment facility equipped with two co-operating robots and two 6 kW high power diode laser to enable the in-house hardening of such blades. Several blade designs from power generation and industrial turbines were successfully laser treated within the first year in operation.
This paper describes generally the setup of the laser treatment facility and the application for low pressure steam turbine blades made of precipitation hardening steels and blades with shroud design, including the post laser heat treatments.
Blue Combustion: Stoichiometric Hydrogen-Oxygen Combustion Under Humidified Conditions
Authors: Schimek Sebastian , Stathopoulos Panagiotis , Tanneberger Tom , Paschereit Christian Oliver 
Published: August 2015

The use of renewable energy sources raises the demand of fast and flexible storage techniques and fast power availability to ensure electrical grid stability. A promising storage approach is the production of hydrogen and oxygen by electrolysis. The possibility of using a completely closed cycle of water, hydrogen and oxygen promises an attractive approach for high efficiency, zero emission energy storage. Since electrolysis can be carried out under high pressure, the compressor part of the gas turbine would be unnecessary, which is beneficial in terms of efficiency. Furthermore, high turbine pressure ratios, compared to typical gas turbine applications, can be reached easily.
However, the combustion of hydrogen and oxygen in gas turbines is a challenging task. Hydrogen and oxygen mixtures are extremely reactive and result in very high flame temperatures. In the present study the feasibility of steam-diluted combustion of hydrogen and oxygen at stoichiometric conditions is shown. A suitable combustor is developed and experimentally validated. The degree of humidity is varied systematically for stoichiometric hydrogen oxygen combustion. Flame shapes, temperature estimations and operating limits are compared and discussed.
Space-Time Gradient Method for Unsteady Bladerow Interaction: Part I — Basic Methodology and Verification
Authors: Yi J. , He L. 
Published: August 2015

For advanced turbomachinery development, there is increasing interest to carry out unsteady analyses for flows through multiple bladerows during a design stage. Even with the huge increase in computer processing power currently available, direct unsteady calculations in a whole annulus domain are still very time consuming. Efficient alternative methods with truncations in time and/or in space have been developed for unsteady turbomachinery flows in the past 20 years or so, but they all are associated with related limitations.
The present development is motivated to maintain as many modelling fidelities of direct unsteady solution methods as possible while still have a significant speed-up. To this end, a new steady-solution-like unsteady time-domain methodology has been developed for bladerow interactions.
No circumferential domain truncation is required so that a direct periodic (repeating) condition can be applied. For each mesh cell, the temporal gradient term as required to balance the discretized unsteady flow equation is obtained by specially sequenced spatial variations of corresponding cells in multiple-passages. Consequently the rotor-stator interface treatment becomes completely compatible to that of a direct unsteady solution. Thus a fully conservative interface is easily achieved, in contrast to existing truncated models where interface treatments tend to be complicated and non-conservative. The simultaneous solution procedure with the space-time gradient (STG) link enables an unsteady flow solution to converge at a rate comparable to that of a steady solution.
The background, motivation/justification, basic methodology and some preliminary verifications are described in this paper as Part I. Further validations and applications with extension to more complex configurations and flow conditions will be presented in Part II.
Power Augmentation Technologies: Part I — Literature Review
Authors: Ancona M. A. , Bianchi M. , Melino F. , Peretto A. 
Published: August 2015

There exists a widespread interest in the application of gas turbine Power Augmentation Technologies (PATs) in both electric power generation and mechanical drive markets. This interest is attributable to liberalization in the power generation sector, increased electric rates during peak demand period and need for a proper selection of the gas turbine in a given application.
In the Part I of this study, a comprehensive literature review of the current technologies — investigating analytical, experimental, and practical aspects — is provided. Moreover, a schematic comparison, useful for the PATs selection, will be presented and discussed.
The Impact of Low-Speed Fan Design on Noise: An Exploratory Study
Authors: Moreau Antoine , Guérin Sébastien 
Published: August 2015

The steady evolution since the 1950’s towards higher bypass ratio engines has enhanced the acoustic role of the fan compared to the jet. This paper addresses the following question: does a further decrease in fan pressure ratio and rotor tip speed provide a significant reduction of fan broadband and tonal noise?
The paper presents two conceptual parametric studies conducted with a fast analytical aerodynamic and acoustic prediction tool. The tool includes an aerodynamic fan design model which provides the quantities necessary to assess the trade-off between efficiency and noise at given thrust conditions. The fan acoustic model has a theoretical formulation for broadband and tonal noise sources which is not based on empirical correlations; it is applied on conventional and contra-rotating fan concepts.
The first study proposes a variation of the design fan pressure ratio and evaluates for each concept its impact on noise at three acoustic off-design points. The results obtained, which are in line with a past NASA study, indicate that the optimum pressure ratio in terms of fan noise is well below the fuel-burn optimum. Significant noise reductions of the broadband and tonal interaction components can be achieved with fans operating in a fully subsonic domain. Alternatively, designing at higher speed and pressure ratio near the fuel-burn optimum may invite to consider the contra-rotating fan as a candidate: it performs there very well in terms of buzz-saw and broadband noise compared to the conventional fan.
The second study addresses the variation of design rotor tip speed at constant fan pressure ratio. Although reduced tip speed may suppress buzz-saw noise, the increased loading related to it implies large blade solidities and wakes which causes a significant increase in broadband noise. Thus, there is an optimum loading that will depend on the severity of fan inflow distortion and on the onset of buzz-saw noise. Here again these conclusions confirm some experimental work performed by NASA on two different fans, and by Rolls-Royce on a third one.
Experimental Investigations on Effects of Unsteady Wakes on the Secondary Flows in the Linear T106 Turbine Cascade
Authors: Kirik Ilker , Niehuis Reinhard 
Published: August 2015

The present work extends previous investigations on the secondary flows around a steady base flow to detailed time-averaged and time-resolved flow field measurements up- and downstream of a low pressure turbine (LPT) cascade. Unsteady inflow was generated by a moving bar system.
The inlet conditions were determined using single hot wire anemometry and a pitot probe. Further detailed measurements of the three-dimensional flow field were carried out downstream of the cascade with triple hot wire anemometry, a conventional five hole pressure probe, and a dynamic pressure probe equipped with a single Kulite sensor. All measurements have been performed with and without moving bars. Cases with different Strouhal numbers and flow coefficients have been considered by varying the pitch of the moving bars between 40 mm and 80 mm and circumferential speed between 10m/s and 20m/s in order to investigate the influence of unsteady inflow in particular on the secondary flow field near the endwalls.
It turned out that the effects of the incoming wakes are evident in the time-accurate data in terms of their interaction with secondary flow vortices. On a time-averaged basis, however, the influence of the incoming wakes on the secondary flow field turned out to be small for the small inlet boundary layer.
Power Augmentation Technologies: Part II — Thermo-Economic Analysis
Authors: Ancona M. A. , Bianchi M. , Melino F. , Peretto A. 
Published: August 2015

There exists a widespread interest in the application of gas turbine Power Augmentation Technologies (PATs) in both electric power generation and mechanical drive markets. This interest is attributable to liberalization in the power generation sector, increased electric rates during peak demand period and need for a proper selection of the gas turbine in a given application.
In the Part II of this study, an analytical evaluation of the ambient temperature effect on gas turbines performance is presented. Further, the achievable power boost due to the installation of the most adopted PAT strategies is deeply investigated. Considering a whole year of operation for a large number of worldwide locations, also the behavior change — due to the use of the PATs — on both the energy production and the economic aspect will be analyzed and discussed.
Simulation of Silo Combustor Liners Transient Behavior for Advanced Design Upgrade
Authors: Fedorov Ilya , Vassiliev Vladimir , Arkhipov Alexandre , Magni Fulvio 
Published: August 2015

Many Alstom heavy-duty gas turbines with a silo combustor are in service and moreover undergoing upgrades for performance augmentation, lifetime extension, and emission reduction. The combustor liners, which are exposed to high gas temperatures, may require design tuning for these upgrades, and therefore reliable simulation of their behavior is of utmost importance.
This paper focuses on a case study of transient behavior of the Hot Gas Casing, a transition liner between compressor, turbine and silo combustor. Following a three-dimensional thermal assessment based on computational fluid dynamics, detailed structural analysis is done to identify the drivers behind different types of Hot Gas Casing deformation, observed after upgraded combustor introduction.
Thermal Barrier Coating application is proposed to reduce Hot Gas Casing bending. The solution was confirmed analytically and successfully introduced in the field. Good correlation of field findings and finite element prediction was found. It is shown that only a combined effect of thermal deformation, cyclic loading and creep may explain the observed behavior of the part.
A detailed design sensitivity study is performed, comparing different approaches to deformation reduction: application of ribs, corrugations and wall thickness increase. The best solution in terms of manufacturability and its impact on part deformation is chosen. It is found that wall corrugation does not provide the desired effect due to the nature of part deformation.
Efficiency Increase in Centrifugal Compressor With Open Impeller by Using Curvilinear Element Blade
Authors: Tsukamoto Kazuhiro , Hiradate Kiyotaka , Sakamoto Kiyohide , Chiba Haruaki , Shinkawa Yasushi 
Published: August 2015

The effect of curvilinear element blade on open-type centrifugal impeller is numerically examined in this research. We compared four different open-type centrifugal impellers. Two of them were linear element blade impellers: one has a positive tangential lean to the rotation at the outlet and the other has negative tangential lean. The other two were curvilinear element blade impellers having different tangential lean profiles. Numerical simulation of steady flow was conducted in one-blade path model with inlet, impeller and vane-less diffuser regions.
The simulation confirm that impellers with negative tangential lean profiles improve the stage efficiency under the flow rate at the design point and the curvilinear element blade improve the stage efficiency not only at the design point but the lower flow rate regions also. The efficiency increase at the design point is obtained not in the vane-less diffuser region but in the impeller region since the negative lean profile reduce the tip-leakage loss near the impeller outlet region. The negative tangential lean profile changes the pressure distribution in the flow passage between two impeller blades. The pressure difference between the pressure surface and the suction surface of one blade near the tip region decrease because of the pressure distribution change. Hence, the mass flow rate of the tip leakage decreases and reduces the loss generation. In addition, the reason why the stage efficiency increases under the lower flow rate conditions by using curvilinear element blade is the suppression effect of the flow separation in the vane-less diffuser. This result indicates that there is a design criteria both tangential lean angle and the inflection point of the profile from positive to negative to suppress the flow separation at the hub side in the vane-less diffuser.
Flow Evolution in a One and a Half Axial Steam Turbine Stage Under Different Operating Conditions
Authors: Paradiso Berardo , Mora Alessandro , Dossena Vincenzo , Gatti Giacomo , Nesti Andrea , Arcangeli Lorenzo , Maceli Nicola 
Published: August 2015

In order to investigate in detail the performance of steam turbine stages the Low Speed Test Rig at Politecnico di Milano has been adapted. The setup consists of a one and an half turbine stage with an inlet guide vane. Two kind of experimental approaches are planned in the project: the first, denominated “performance”, has been carried out by the OGTL department of GE Oil&Gas Florence while, at the same time, Politecnico di Milano performed detailed inter-stage measurements with steady probes and time resolved high response pressure probes. An axial steam turbine stage was tested under several operating conditions in terms of rotational speed, mass flow and inlet angle with the aim to provide the functional curves of the machine together with detailed flow-field measurements. In this paper, a detailed description of the inter-stage flow-field is presented for the most relevant operating condition. Then, a comparison between three different points at the same rotational speed (but different mass flow) is proposed. Finally, the effects of different axial gaps on the overall performance of the stage are discussed.
In particular, two different vane-rotor axial gaps have been tested by traversing pressure and temperature probes in three different axial planes. The first measurement plane is located at the first stator exit with the aim to provide details of the inlet swirl angle and 3D flow-field generated by the IGV. In the second plane, located at the rotor exit, the effect of different load conditions on the rotor performance and average flow-field is discussed. Finally, the measurements obtained in the third plane, placed at the second stator exit, are afterwards compared with the one obtained in the first plane, in order to evidence the influence of an unsteady inlet flow-field on the stator behaviour. The aim of the work is to provide very detailed aerodynamic measurements; this large amount of data will be used to validate the results of the CFD simulation carried out in the design stage. In this paper the preliminary findings of the steady flow-field will be presented as the basis for further analysis.
The Characteristics of Rotating Instabilities in Low Pressure Steam Turbines at Low Volume Flow Operation
Authors: Sigg Roland , Rice Timothy 
Published: August 2015

For flexible operation steam turbines may operate occasionally at low load. Operation away from the original design regime looks set to be an increasing trend mainly due to the presence of intermittently available renewable energy sources in the grid. This paper sets out an approach for considering low flow effects on turbine designs.
At low load operating conditions rotating instabilities (RIS) can occur in the rear stages of LP steam turbines. The instabilities are comparable in many ways to rotating stall in compressors. Ideally the turbine blade natural frequencies should be designed to avoid the frequencies generated by the RIS system.
The characteristics of RIS systems were experimentally investigated to understand the dependency with both flow coefficient and exhaust configuration. Correlations have been developed to characterize the dynamic pressure amplitudes and the fractional speed of the RIS moving around the wheel. The presented correlation based method is shown calibrated for a specific blade design.
Two different test rigs provide the basis for the work presented. A low pressure model steam turbine provided detailed information for key blade/exhaust combinations. A simplified small scale air turbine was used to provide additional input for the behavior with alternative exhaust back wall position. Observations of the characteristic RIS behavior from model turbine tests are set in context with observed changes in the flow field.