| 1. |
- Chernoray, Valery, 1975
(författare)
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Prediction of Laminar-Turbulent Transition on an Airfoil at High Level of Free-Stream Turbulence
- 2015
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Ingår i: Progress in Flight Physics Vol. 7. - 9785945881655 ; , s. 704-
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Prediction of laminar-turbulent transition at high level of free-stream turbulence in boundary layers of airfoil geometries with external pressure gradient changeover is in focus. The aim is a validation of a transition model for transition prediction in turbomachinery applications. Numerical simulations have been performed by using a transition model by Langtry and Menter for a number of different cases of pressure gradient, at Reynolds number-range, based on the airfoil chord, 50 000 ≤ Re ≤ 500 000 and free-stream turbulence intensities 2 % and 4 %. The validation of the computational results against the experimental data showed good performance of used turbulence model for all test cases.
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| 2. |
- Wärmefjord, Kristina, 1976, et al.
(författare)
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Joining in Nonrigid Variation Simulation
- 2016
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Ingår i: Computer-aided Technologies - Applications in Engineering and Medicine. - 9789535127888
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Geometrical variation is closely related to fulfillment of both functional and esthetical requirements on the final product. To investigate the fulfillment of those requirements, Monte Carlo (MC)-based variation simulations can be executed in order to predict the levels of geometrical variation on subassembly and/or product level. If the variation simulations are accurate enough, physical tests and try-outs can be replaced, which reduce cost and lead-time. To ensure high accuracy, the joining process is important to include in the variation simulation. In this chapter, an overview of nonrigid variation simulation is given and aspects such as the type and number of joining points, the joining sequence and joining forces are discussed.
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| 3. |
- Brinkfeldt, Klas, et al.
(författare)
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Design and Fabrication of a SiC-Based Power Module with Double-Sided Cooling for Automotive Applications
- 2016
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Ingår i: Lecture Notes in Mobility. - Cham : Springer International Publishing. - 2196-5544 .- 2196-5552. ; , s. 157-171, s. 157-172
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The electrification of drive trains combined with special requirements of the automotive and heavy construction equipment applications drives the development of small, highly integrated and reliable power inverters. To minimize the volume and increase the reliability of the power switching devices a module consisting of SiC devices with double sided cooling capability has been developed. There are several benefits related to cooling the power devices on both sides. The major improvement is the ability to increase the power density, and thereby reduce the number of active switching devices required which in turn reduces costs. Other expected benefits of more efficient cooling are reductions in volume and mass per power ratio. Alternatively, improved reliability margins due to lower temperature swings during operation are can be expected. Removing the wire bonds on the top side of the devices is expected to improve the reliability regardless, since wire bonds are known to be one of the main limitations in power switching devices. In addition, it is possible to design the package with substantially lower inductance, which can allow faster switching of the devices. In this paper the design, simulations and fabrication process of a double sided SiC-based power module are presented.
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| 4. |
- Grönstedt, Tomas, 1970
(författare)
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Propulsion Systems Modeling
- 2012
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Ingår i: Physics-Based Modeling & Simulation for Aerospace Systems, VKI lecture series. - 9782875160386
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The present text draws attention to three interrelated topics; aero engine system simulation, evaluation of losses through exergy analysis and the search for more energy efficient power plants. The first chapter reviews the historical development of simulation tools, with anemphasis on generic programs, and discusses efficient numerical solution techniques and suitable solvers. A short discussion on multidisciplinary optimization tools is given. The chapter also briefly reviews the state of the art in terms of commercially available software for aeroengine simulation and discusses the needs and uses in industrial applications. The second chapter introduces the concept of exergy analysisand develops the necessary equations for applying the theory to evaluate losses in aero engines. The third chapter pursues future ultra efficient engines designed for an estimated 2050 technology level. Theanalysis is based on mission optimization starting with a conventional three shaft engine. The concept of exergy analysis is then used to show where in the cycle that major efficiency improvements of such an engine can be accomplished. This is followed by a discussion on a numberof cycle innovations that can target the observed losses. Optimization is used to quantify the improvement potential.
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| 5. |
- Kyprianidis, Konstantinos G.
(författare)
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Future Aero Engine Designs : An Evolving Vision
- 2011. - 1st
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Ingår i: Advances in Gas Turbine Technology. - Rijeka, Croatia : InTech. - 9789533076119 ; , s. 3-24
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Kyprianidis, Konstantinos
(författare)
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Gas Turbines for Power and Propulsion
- 2015. - 1
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Ingår i: Handbook of Clean Energy Systems. - Chichester, West Sussex, UK : John Wiley & Sons. - 9781118388587 ; , s. 1-25
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Bokkapitel (refereegranskat)abstract
- For over seven decades, the gas turbine has been used successfully in a variety of applications including aircraft, ship, and surface vehicle propulsion as well as for electrical power and heat generation. The gas turbine is in essence a type of internal combustion engine comprising in its simplest form a compressor, a combustor, and a turbine. It can utilize a variety of different fuels, most commonly natural gas and kerosene (Jet-A).The gas turbine has played a key role in the expansion of jet transportation and is currently the prime mover for almost all commercial applications, other than light aircraft. It also has had a considerable impact in the power generation sector with efficiencies in excess of 40% for simple cycles, and close to 60% for combined cycles. Over the next decades, it is expected that the gas turbine will continue to play a significant role in the power generation and propulsion market.This article covers the fundamentals of gas turbine design, performance, and future technology development. First, a short presentation of the fundamental thermodynamics relating to the gas turbine is given. It is followed by an ideal analysis of three major cycles: the simple cycle, the intercooled cycle, and the intercooled recuperated cycle. Typical losses for gas turbine components are discussed along with relevant performance modeling methods. The fundamental principles of gas turbine conceptual design are presented followed by an assessment of the real performance of the three major cycles. Finally, a critical review is presented of future gas turbine concepts and their enabling technologies, with the primary focus on civil aircraft propulsion. Recent development trends and the primary research and development efforts by major gas turbine manufacturers are discussed in detail.
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| 7. |
- Kyprianidis, Konstantinos, et al.
(författare)
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On Intercooled Turbofan Engines
- 2013. - 1st
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Ingår i: Progress in Gas Turbine Performance. - Rijeka, Croatia : InTech. - 9789535111665 ; , s. 3-24
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Bokkapitel (refereegranskat)
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| 8. |
- Zhou, Wei, et al.
(författare)
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Dynamic modeling and coordinate control for an engine-generator set
- 2019
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Ingår i: Lecture Notes in Electrical Engineering. - Singapore : Springer Singapore. - 1876-1119 .- 1876-1100. ; , s. 1015-1033
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The engine-generator set is widely used in extended-range electric vehicles. Dynamic coordinate control of an engine-generator set is very important for its efficient and stable operation. This paper firstly presents an average model of a diesel engine-generator set. Both the engine and generator system model are built in a semi-physical way instead of traditionally map-based. Experimental results show that the model is able to reflect the real system very well in both steady and transient states. Based on the established model, two typical dynamic coordinate control schemes are compared in terms of energy efficiency and dynamic performance. Insights on how to appropriately design a dynamic coordinate controller for the engine-generator set are briefly summarized.
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| 9. |
- Baheta, Aklilu, et al.
(författare)
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CFD Analysis of Fouling Effects on Aerodynamics Performance of Turbine Blades
- 2018
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Ingår i: Rotating Machineries. - Singapore : Springer. - 9789811323560 - 9789811323577 ; , s. 73-84
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Bokkapitel (refereegranskat)abstract
- Fouling on gas turbine blades is detrimental to process operation as it may, over a period of time, reduce the blade efficiency and consequently the turbine’s efficiency. With the limitation of today’s technology, experimental study or real-life observation of fouling in a gas turbine is beyond imagination of maintenance engineers. Hence, the effect of fouling cannot be fully quantified for the engineers to come out with mitigation or intervention plans. Nevertheless, computational fluid dynamics (CFD) may provide a good simulation to understand the phenomena. In this chapter, recent effort involving CFD study on the influence of fouling on gas turbine performance is presented. Firstly, the nature of fouling on the gas turbine and the general consequences are discussed. This is followed by an elaboration on how CFD study has been conducted by the authors. Finally, the findings from the study are discussed.
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| 10. |
- Gojon, Romain, et al.
(författare)
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Large Eddy Simulation of Highly Compressible Jets with Tripped Boundary Layers
- 2019. - vol. 25
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Ingår i: Direct and Large-Eddy Simulation XI. ERCOFTAC Series.. - Cham : Springer. - 9783030049140 - 9783030049157 ; , s. 333-339
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Bokkapitel (refereegranskat)abstract
- In high-speed aircraft, supersonic jets used for propulsion can lead to very intense aerodynamically generated acoustic noise. Thus, there is a need to study the aerodynamic and aeroacoustic properties of highly compressible jets. In previous studies (Gojon et al, Temperature effects on the aerodynamic and acoustic fields of a rectangular supersonic jet, 2017, [1], Gojon et al, On the response of a rectangular supersonic jet to a near-field located parallel flat plate, 2017, [2]), several simulations of supersonic jets have been conducted. Unfortunately, the turbulence intensity at the nozzle exit was dependent on the internal geometry of the nozzle and could not be tuned. This is a pity given that, as shown experimentally (Zaman, AIAA J, 50(8):1784–1795, 2012, [3]) and numerically (Bogey et al, J Fluid Mech, 701:352–385, 2012, [4], Brés et al, Nozzle wall modeling in unstructured large eddy simulations for hot supersonic jet predictions, 2013, [5]) for subsonic and supersonic jets, the boundary layer state of the jet affects the jet flow and noise.
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