| 61. |
- Jonsson, Isak, 1990, et al.
(författare)
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Infrared thermography investigation of heat transfer on outlet guide vanes in an engine exit module
- 2019
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Ingår i: 13th European Turbomachinery Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2019.
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Konferensbidrag (refereegranskat)abstract
- This paper presents experimental results of heat transfer coefficient on an outlet guide vane (OGV) in an engine exit Module (EEM) at engine-representative conditions. The results were obtained in Chalmers OGV-LPT test facility with a newly developed method to measure heat transfer with high accuracy that is applicable to a large variety of geometries. A thin-walled OGV was manufactured with an internal water heating system and surface temperature was measured by IR thermography. An extensive effort has been made to mitigate all major sources of uncertainty and results from three different load cases at Reynolds number 235000 is presented. The current study is closing the gap which previously existed in the literature by providing data on heat transfer on EES OGVs under engine representative conditions. These results are crucial for designing future high-bypass ratio aero-engines which is a new radical concept requiring improvement of the existing design of EEMs.
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| 62. |
- Pasternak, M., et al.
(författare)
-
Diesel engine performance mapping using a parametrized mixing time model
- 2018
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Ingår i: International Journal of Engine Research. - : SAGE Publications. - 1468-0874 .- 2041-3149. ; 19:2, s. 202-213
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Tidskriftsartikel (refereegranskat)abstract
- A numerical platform is presented for diesel engine performance mapping. The platform employs a zero-dimensional stochastic reactor model for the simulation of engine in-cylinder processes. n-Heptane is used as diesel surrogate for the modeling of fuel oxidation and emission formation. The overall simulation process is carried out in an automated manner using a genetic algorithm. The probability density function formulation of the stochastic reactor model enables an insight into the locality of turbulence–chemistry interactions that characterize the combustion process in diesel engines. The interactions are accounted for by the modeling of representative mixing time. The mixing time is parametrized with known engine operating parameters such as load, speed and fuel injection strategy. The detailed chemistry consideration and mixing time parametrization enable the extrapolation of engine performance parameters beyond the operating points used for model training. The results show that the model responds correctly to the changes of engine control parameters such as fuel injection timing and exhaust gas recirculation rate. It is demonstrated that the method developed can be applied to the prediction of engine load–speed maps for exhaust NO x , indicated mean effective pressure and fuel consumption. The maps can be derived from the limited experimental data available for model calibration. Significant speedup of the simulations process can be achieved using tabulated chemistry. Overall, the method presented can be considered as a bridge between the experimental works and the development of mean value engine models for engine control applications.
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| 63. |
- Saccullo, Michael, 1984, et al.
(författare)
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Dual Fuel Methanol and Diesel Direct Injection HD Single Cylinder Engine Tests
- 2018
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2018-April
-
Tidskriftsartikel (refereegranskat)abstract
- Laws concerning emissions from heavy duty (HD) internal combustion engines are becoming increasingly stringent. New engine technologies are needed to satisfy these new requirements and to reduce fossil fuel dependency. One way to achieve both objectives can be to partially replace fossil fuels with alternatives that are sustainable with respect to emissions of greenhouse gases, particulates and nitrogen oxides (NOx). A suitable candidate is methanol. The aim of the study presented here was to investigate the possible advantages of combusting methanol in a heavy duty Diesel engine. Those are, among others, lower particulate emissions and thereby bypassing the NOx-soot trade-off. Because of methanol's poor auto-ignition properties, Diesel was used as an igniting sources and both fuels were separately direct injected. Therefore, two separate standard common rail Diesel injection systems were used together with a newly designed cylinder head and adapted injection nozzles. This study serves as a proof-of-concept, demonstrating that methanol can successfully be used in a high pressure Diesel injection system. Additionally, the combustion properties of the dual fuel system were compared to those of pure Diesel with the same dual injection strategy. Methanol offered comparable combustion efficiencies to conventional Diesel with lower NOx and significantly lower soot emissions. A design of experiments study was performed to characterize the methanol-diesel system's behavior in detail at a single speed-load point. A sweet spot analysis showed potential for optimizing the given setup towards even higher indicated gross efficiency with very low soot and low NOx.
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| 64. |
- Thoma, Evangelia Maria, 1996, et al.
(författare)
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Quantifying the Environmental Design Trades for a State-of-the-Art Turbofan Engine
- 2020
-
Ingår i: Aerospace. - : MDPI AG. - 2226-4310. ; 7:10, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Aircraft and engine technology have continuously evolved since their introduction and significant improvement has been made in fuel efficiency, emissions, and noise reduction. One of the major issues that the aviation industry is facing today is pollution around the airports, which has an effect both on human health and on the climate. Although noise emissions do not have a direct impact on climate, variations in departure and arrival procedures influence both CO2 and non-CO2 emissions. In addition, design choices made to curb noise might increase CO2 and vice versa. Thus, multidisciplinary modeling is required for the assessment of these interdependencies for new aircraft and flight procedures. A particular aspect that has received little attention is the quantification of the extent to which early design choices influence the trades of CO2, NOx, and noise. In this study, a single aisle thrust class turbofan engine is optimized for minimum installed SFC (Specific Fuel Consumption). The installed SFC metric includes the effect of engine nacelle drag and engine weight. Close to optimal cycles are then studied to establish how variation in engine cycle parameters trade with noise certification and LTO (Landing and Take-Off) emissions. It is demonstrated that around the optimum a relatively large variation in cycle parameters is allowed with only a modest effect on the installed SFC metric. This freedom in choosing cycle parameters allows the designer to trade noise and emissions. Around the optimal point of a state-of-the-art single aisle thrust class propulsion system, a 1.7 dB reduction in cumulative noise and a 12% reduction in EINOx could be accomplished with a 0.5% penalty in installed SFC.
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| 65. |
- Xisto, Carlos, 1984, et al.
(författare)
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Assessment of CO2 and NOx emissions in intercooled pulsed detonation turbofan engines
- 2018
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Ingår i: Proceedings of the ASME Turbo Expo. ; 1
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Konferensbidrag (refereegranskat)abstract
- In the present paper, the synergistic combination of intercooling with pulsed detonation combustion is analyzed concerning its contribution to NOxand CO2emissions. CO2is directly proportional to fuel burn and can, therefore, be reduced by improving specific fuel consumption and reducing engine weight and nacelle drag. A model predicting NOxgeneration per unit of fuel for pulsed detonation combustors, operating with jet-A fuel, is developed and integrated within Chalmers University's gas turbine simulation tool GESTPAN. The model is constructed using CFD data obtained for different combustor inlet pressure, temperature and equivalence ratio levels. The NOxmodel supports the quantification of the trade-off between CO2and NOxemissions in a 2050 geared turbofan architecture incorporating intercooling and pulsed detonation combustion and operating at pressures and temperatures of interest in gas turbine technology for aero-engine civil applications.
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| 66. |
- Xisto, Carlos, 1984, et al.
(författare)
-
Development of fuel and heat management systems for liquid hydrogen powered aircraft
- 2020
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The presentation describes the recent developments in the design of the fuel and heat management systems for liquid hydrogen powered aircraft within the H2020 project ENABLEH2. The fuel distribution system main task is to deliver the right amount of hydrogen to the combustion chamber at an adequate pressure. This requires the usage of fuel pumps, valves, insulated piping, and a fuel control system to adjust the fuel flow for a given engine rating. Moreover, since liquid hydrogen is stored at cryogenic temperatures (-253C), it also requires the integration of heat exchanger technology to increase the fuel temperature up to a state where it can be efficiently mixed with air and combusted. The combination of hydrogen high specific heat with cryogenic temperatures results in formidable cooling capacity that can be explored by compact heat-exchanger solutions. Concepts that use existing engine aero-surfaces located after rotating turbomachinery are currently being investigated a Chalmers University of Technology. A recently commissioned facility to investigate the potential benefits of a compressor flow cooling heat rejection system will also be discussed. The test facility comprises a vertically mounted low-speed 2.5 stage compressor designed to operate continuously at rotor mid-span chord Reynold number up to 600,000, which is representative of a large-size future geared turbofan engine. Detailed aerothermal studies at TRL4 will be conducted to calibrate in-house design methods for radical core integrated heat exchangers. The facility is driven by a 147kW electric drive at a nominal speed of 1920 RPM. Traverse access is included in two 18-degree sectors for all the rotor-stator interfaces. At the upstream plane of the compressor outlet-guide-vane, four independent access traverse systems are included for a 360-degree access. Downstream, an ABB robot arm with a U-shaped probe mount provides full volume probing access in the exit compressor duct.
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| 67. |
- Yamaguchi, Akichika, et al.
(författare)
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Spray Characterization of Gasoline Direct Injection Sprays under Fuel Injection Pressures up to 150 MPa with Different Nozzle Geometries
- 2019
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2019-January:january
-
Tidskriftsartikel (refereegranskat)abstract
- Maximum fuel injection pressures for GDI engines is expected to increase due to positive effects on emissions and engine-efficiency. Current GDI injectors have maximum operating pressures of 35 MPa, but higher injection pressures have yielded promising reductions in particle number (PN) and improved combustion stability. However, the mechanisms responsible for these effects are poorly understood, and there have been few studies on fuel sprays formed at high injection pressures. This paper summarizes experimental studies on the properties of sprays formed at high injection pressures. The results of these experiments can be used as inputs for CFD simulations and studies on combustion behavior, emissions formation, and combustion system design. The experiments were conducted using an injection rate meter and optical methods in a constant volume spray chamber. Injection rate measurements were performed to determine the injectors' flow characteristics. Spray imaging was performed using a high-speed video camera. Several spray properties such as the liquid spray penetration, spray plume angle, and the spray breakup point were determined as functions of the fuel injection pressure and injected fuel mass by image post-processing. The impact of fuel pressure on spray droplet size was also investigated using two-component Phase Doppler Interferometry. Piezoelectric injectors for diesel engines were used with modified nozzles that produce sprays resembling those generated in gasoline engines. Experiments were performed with fuel injection pressures ranging from 20 to 150 MPa, and chamber pressures of 0.1 and 0.6 MPa. In addition, four different nozzles with three different nozzle configurations and either 6 or 10 holes were used to determine how hole geometry affects spray formation. The study's key findings are that increasing the fuel injection pressure advances spray breakup and creates smaller droplets, improving mixture formation and accelerating evaporation. The nozzle type and the ambient pressure both significantly affect aspects of spray behavior such as spray tip development.
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| 68. |
- Ferreira da Silva, Janaina, et al.
(författare)
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Considering the Effects of Turbine Blade Cooling on Engine Performance Estimation
- 2017
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Ingår i: Proceedings of the 23rd ISABE conference 2017.
-
Konferensbidrag (refereegranskat)abstract
- In gas turbines, a way to improve the engine performance is by increasing the Turbine Inlet Temperature (TIT). However, increasing TIT causes an increase in heat load of turbine components. A limit in the performance improvement is imposed by the permissible metal temperature. Engine running above the melting point of material might be achieved only by cooling turbine components or using Thermal Barrier Coating (TBC). This thermal management must be done to ensure safe and durable engine operation. The most common method to cool turbine components is bleed a portion of the compressor airflow and inject it on blades and disks. Unfortunately, the extraction has an adverse effect on engine performance compared with engine without bleed. In this paper, the cooling effects on engine performance estimation at preliminary design was analyzed. The engine configuration used in the study is a turboshaft – single spool gas turbine engine. The coolant parameters are estimated using the method developed by Young and Wilcock. The results showed that there is a marked difference on performance for uncooled and cooled turbine blades, highlighting the importance in considering the cooling on performance estimation since design preliminary phase. Ignoring the cooling in evaluation can cause up to 15% difference in net specific work.
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| 69. |
- Orbay, Raik, 1974, et al.
(författare)
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Off-Design Performance Investigation of a Low Calorific Value Gas Fired Generic-Type Single-Shaft Gas Turbine.
- 2008
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Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 130:3
-
Tidskriftsartikel (refereegranskat)abstract
- When low calorific value gases are fired, the performance and stability of gas turbines may deteriorate due to a large amount of inertballast and changes in working fluid properties. Since it is rather rare to have custom-built gas turbines for low lower heating value (LHV) operation, the engine will be forced to operate outside its design envelope. This, in turn, poses limitations to usable fuel choices. Typical restraints are decrease in Wobbe index and surge and flutter margins for turbomachinery. In this study, an advanced performance deck has been used to quantify the impact of firing low-LHV gases in a generic-type recuperated as well as unrecuperated gas turbine. A single-shaft gas turbine characterized by a compressor and an expander map is considered. Emphasis has been put on predicting the off-design behavior. The combustor is discussed and related to previous experiments that include investigation of flammability limits, Wobbe index, flame position, etc. The computations show that at constant turbine inlet temperature, the shaft power and the pressure ratio will increase; however, the surge margin will decrease. Possible design changes in the component level are also discussed. Aerodynamic issues (and necessary modifications) that can pose severe limitations on the gas turbine compressor and turbine sections are discussed. Typical methods for axial turbine capacity adjustment are presented and discussed.
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| 70. |
- Pons, Arion, 1995, et al.
(författare)
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Multiparameter Solution methods for semi-structured aeroelastic flutter problems
- 2017
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Ingår i: AIAA Journal. - 1533-385X .- 0001-1452. ; 55:10, s. 3530-3538
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents several new methods for the solution of aeroelastic flutter problems with a partial polynomial structure: problems consisting of a mix of polynomial and more complex nonlinear components. The focus is particularly on systems that use Theodorsen aerodynamics: for such systems, four new solution algorithms are devised. Two of these are direct but yield approximate results, and two are iterative. These algorithms are tested on an example system, and their computational characteristics are investigated and discussed. Three of them are suitable for practical implementation; the fourth is too computationally intensive to be of great practical use. Extensions and improvements to these algorithms, and the overall methods used, are also discussed.
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