| 111. |
- Zhao, Xin, 1986, et al.
(författare)
-
Experimental Validation of the Aerodynamic Characteristics of an Aero-engine Intercooler
- 2017
-
Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 139:5
-
Tidskriftsartikel (refereegranskat)abstract
- Porous media model computational fluid dynamics (CFD) is a valuable approach allowing an entire heat exchanger system, including the interactions with its associated installation ducts, to be studied at an affordable computational effort. Previous work of this kind has concentrated on developing the heat transfer and pressure loss characteristics of the porous medium model. Experimental validation has mainly been based on the measurements at the far field from the porous media exit. Detailed near field data are rare. In this paper, the fluid dynamics characteristics of a tubular heat exchanger concept developed for aero-engine intercooling by the authors are presented. Based on a rapid prototype manufactured design, the detailed flow field in the intercooler system is recorded by particle image velocimetry (PIV) and pressure measurements. First, the computational capability of the porous media to predict the flow distribution within the tubular heat transfer units was confirmed. Second, the measurements confirm that the flow topology within the associated ducts can be described well by porous media CFD modeling. More importantly, the aerodynamic characteristics of a number of critical intercooler design choices have been confirmed, namely, an attached flow in the high velocity regions of the in-flow, particularly in the critical region close to the intersection and the in-flow guide vane, a well-distributed flow in the two tube stacks, and an attached flow in the cross-over duct.
|
|
| 112. |
- Forslund, Anders, 1982
(författare)
-
Uncertainty and Robustness in Aerospace Structures
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Engineering is not an exact science. In fact, all engineering activity contain some degree of assumption, simplification, idealization, and abstraction. When engineered creations meet reality, every manufactured product behaves differently. This variation can be detrimental to product quality and functionality. In an aerospace context, this variation may even result in serious threats to the safety and reliability of aircraft. However, it is not the variation in and of itself that is harmful, but the effects it imposes on functionality—an important distinction to make. Reducing sources of variation is often associated with tightening tolerances and increasing cost. Instead, it is preferable to eliminate the effects of this variation by making designs more robust. This idea is at the core of robust design methodology. Aerospace is an industry characterized by the complexity of its products and the multidisciplinary nature of its product development. In such contexts, there are significant barriers against implementing uncertainty-based design practices. The research presented in this thesis aims at identifying the role of robust design in general, and geometry assurance in particular, in the early phases of aerospace component design. Further, this thesis proposes a methodology by which geometry assurance practices may be implemented in this setting. The methodology consists of a modelling approach linked to a multidisciplinary simulation environment. In a series of case studies, the methodology is tested in an industrial setting. The capability of the methodology is demonstrated through several applications, in which the effects of geometric variation on the aerodynamic, thermal, and structural performance of a load-bearing turbofan component are analysed. Investigated effects include part variation, fixture variation, part configuration and welding. The proposed methodology overcomes many of the current barriers, making it more feasible to assess geometric variation in the early design phases. Despite some limitations, the methodology contributes to an academic understanding of how to evaluate geometric variation in multidisciplinary simulations and provides a tool for industry. Geometric variation is only one source of uncertainty amongst many others. By evaluating geometric variation against the framework of uncertainty quantification, this thesis addresses the relative importance of geometry assurance against other product development activities.
|
|
| 113. |
- Madrid, Julia, 1988, et al.
(författare)
-
Development of a conceptual framework to assess producibility for fabricated aerospace components
- 2016
-
Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 41, s. 681-686
-
Konferensbidrag (refereegranskat)abstract
- The aerospace industry is undergoing an intense competitive pressure due to new market demands and regulations. In the next 20 years thenumber of aircraft in service is expected to double. At the same time, there is a rapid development of new technologies to fulfil tougherrequirements, typically with regards to lower emissions and fuel consumption, where lightweight is a key issue. Along with this, some aircraftenginemanufactures have adopted a fabrication approach to build their large structural components. Within fabrication, smaller parts arewelded together into the final shape. This manufacturing approach has significantly broadened the number of possible variants of a definedproduct and production concept. In addition, fabrication has brought to the forefront important problems such as geometrical variation and weldquality. Tailoring the product design to fulfil customer requirements and moreover, tailoring the fabrication process to suit the product design,becomes really complex. Therefore, a systematic approach is required to assess the producibility of the different design solutions in order tosecure the final product quality throughout the fabrication process. In this paper, a conceptual framework, by means of a model, is presented.This model serves to identify, in a structural way, the parameters and features that are contributors to variation in the process quality output.Furthermore, the model helps to describe the parameters within the manufacturing process that build up the quality into the product, andultimately, what are the product characteristics that deliver the final quality to the custome
|
|
| 114. |
- Stadler, Michael, et al.
(författare)
-
A Customised Finn Dinghy Rudder for Optimal Olympic Performance
- 2020
-
Ingår i: Proceedings (MDPI). - Basel Switzerland : MDPI. - 2504-3900. ; 49:1
-
Konferensbidrag (refereegranskat)abstract
- Because of the long history of the Finn Dinghy sailing class, the difference between a gold medal and a mediocre result often comes down to personal mistakes of the sailor, or to who has the most optimised equipment. Regarding the latter, the Finn class rules permit certain design variations of the hull, mast, sail and rudder. In the current contribution, we describe a method for developing a customised rudder system aimed at optimal performance during the Tokyo 2020 Olympics. Based on hydrodynamic analysis of existing rudder designs, an improved rudder geometry was developed. Based on the concept geometry, the rudder and tiller were structurally designed and manufactured to achieve high stiffness and sufficient strength, while respecting the minimum mass requirements as specified by the rules.
|
|
| 115. |
- Vallhagen, Johan, 1965, et al.
(författare)
-
An approach for producibility and DFM-methodology in aerospace engine component development
- 2013
-
Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 11, s. 151-156
-
Konferensbidrag (refereegranskat)abstract
- The competitiveness in the aerospace industry is steadilly increasing, at the same time there is a rapid development of new technology for next generations of jet engines. To achieve one of the most important goals, reducing weight, fabrication of structural components is one possible approach, common to many aerospace manufacturers. However, the engineering work becomes more difficult and requires new knowledge. Production becomes significantly more complicated as the need of different manufacturing processes increases, as well as the complexity of other production related activities. In the paper, definitions of producibility and manufacturability are discussed, together with related metrics for measurement of the impact of the product design on a production system. The result is a recommended set of methodologies and tools to manage and evaluate the manufacturing interests and targets, and how they must be reached and balanced within the product development process, in order to improve producibility. The work has also identified gaps and opportunities for improvements, and suggested an approach for next step in order to increase producibility in manufacturing of aerospace engine components
|
|
| 116. |
- Wärmefjord, Kristina, 1976, et al.
(författare)
-
Joining in Nonrigid Variation Simulation
- 2016
-
Ingår i: Computer-aided Technologies - Applications in Engineering and Medicine. - 9789535127888
-
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.
|
|
| 117. |
- Acquaviva, Alessandro, 1987, et al.
(författare)
-
Computationally Efficient Modeling of Electrical Machines With Cooling Jacket
- 2019
-
Ingår i: IEEE Transactions on Transportation Electrification. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2332-7782. ; 5:3, s. 618-629
-
Tidskriftsartikel (refereegranskat)abstract
- Modeling of electrical machines is a multiphysics problem. Depending on the phenomena of interest and the computational time constraint, this can be done at different levels of detail. In this article, the main approaches to model the thermal behavior of electrical machines with a liquid cooled casing around the stator (often referred to as cooling jacket) are analyzed and a novel approach is presented. The proposed method aims at creating computationally efficient 3-D multiphysics models of electrical machines with liquid cooled jacket. This model is based on the assumption of a fully developed flow in the cooling jacket which allows to scale the computational fluid dynamics (CFD) simulation to 1-D. The slot with a two layer concentrated winding and potting material is modeled using a composite material comprising of both the conductors and slot filler. Similarly, a unified material is used to model the end-windings. Experimental results on a traction machine for vehicle applications are presented showing good agreement with the simulations. Also, a comparison with a 3-D CFD is presented to verify the pressure drop in the pipe bend. Finally, the model is used to simulate a dynamic load cycle, which would be computationally extremely demanding with combined 3-D CFD and thermal FEA of the machine and its cooling.
|
|
| 118. |
- Arora, Sampann, et al.
(författare)
-
A partitioned FSI methodology for analysis of sloshing-induced loads on a fuel tank structure
- 2020
-
Ingår i: Proceedings of the 6th European Conference on Computational Mechanics: Solids, Structures and Coupled Problems, ECCM 2018 and 7th European Conference on Computational Fluid Dynamics, ECFD 2018. ; , s. 3037-3048
-
Konferensbidrag (refereegranskat)abstract
- Liquid sloshing is a source of major concern in the structural design of containers. In fuel tanks of heavy duty trucks, with capacities of up to 900 litres, this phenomenon is capable of causing fuel to impact the container tank with high forces, and exposing the vulnerable parts of the tank to heavy dynamic loads. This highly non-linear and transient phenomenon is simulated here using the commercial Computational Fluid Dynamics (CFD) code STAR-CCM+. The two phase problem is solved using the VOF interface capturing approach. Owing to the thin walled structures of the fuel tank, it becomes important to account for the effects of Fluid-Structure Interaction (FSI). To this end, a partitioned FSI methodology is employed by coupling the CFD and Finite Element Analysis (FEA) solvers for this multi-physics problem. One-way and two-way coupled FSI methodologies are compared with experimental results. The one-way coupled simulations yield good agreement of wall deformations with the experiments for low filling levels. While the two-way coupled FSI analysis corroborates well with the experiments for all filling levels, its high computational costs render the one-way coupled methodology a promising tool to analyse sloshing for industrial applications. This coupling strategy could inform a fuel tank design suited to prevent structural damage due to sloshing, thus contributing towards its safety and longevity.
|
|
| 119. |
- Boscaglia, Luca, 1991, et al.
(författare)
-
Numerically-based Reduced-order Thermal Modeling of Traction Motors
- 2021
-
Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 57:4, s. 4118-4129
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an approach based on numerical reduced-order modeling to analyze the thermal behavior of electric traction motors. In this study, a single conjugate heat transfer analysis provides the possibility to accurately predict thermal performances by incorporating both computational fluid dynamic and heat transfer modules. Then, the developed model is used as the basis for deriving a fast reduced-order model of the traction motor enabling prediction of motor thermal behaviour in duty cycles with a high number of operating points. All the results achieved are verified using flow and temperature measurements carried out on a traction motor designed and built for a traction application. A good agreement between the measured and estimated values of flows and temperatures is achieved while keeping the computation time within a reasonable range for both the full-order and reduced-order conjugate heat transfer models. The optimized full-order model can be run in minutes and the reduced-order model computation time is less than one second per operating point. The transient simulation based on reduced-order model is conducted and both the learning phase and validation results are well illustrated. It is shown than the deviation of the reduced-order model in estimating the motor thermal performance is less than one Celsius degree from the full-order model.
|
|
| 120. |
- El-Gabry, Lamyaa, et al.
(författare)
-
Measurements of Hub Flow Interaction on Film Cooled Nozzle Guide Vane in Transonic Annular Cascade
- 2015
-
Ingår i: Journal of turbomachinery. - : ASME International. - 0889-504X .- 1528-8900. ; 137:8
-
Tidskriftsartikel (refereegranskat)abstract
- An experimental study has been performed in a transonic annular sector cascade of nozzle guide vanes (NGVs) to investigate the aerodynamic performance and the interaction between hub film cooling and mainstream flow. The focus of the study is on the endwalls, specifically the interaction between the hub film cooling and the mainstream. Carbon dioxide (CO2) has been supplied to the coolant holes to serve as tracer gas. Measurements of CO2 concentration downstream of the vane trailing edge (TE) can be used to visualize the mixing of the coolant flow with the mainstream. Flow field measurements are performed in the downstream plane with a five-hole probe to characterize the aerodynamics in the vane. Results are presented for the fully cooled and partially cooled vane (only hub cooling) configurations. Data presented at the downstream plane include concentration contour, axial vorticity, velocity vectors, and yaw and pitch angles. From these investigations, secondary flow structures such as the horseshoe vortex, passage vortex, can be identified and show the cooling flow significantly impacts the secondary flow and downstream flow field. The results suggest that there is a region on the pressure side (PS) of the vane TE where the coolant concentrations are very low suggesting that the cooling air introduced at the platform upstream of the leading edge (LE) does not reach the PS endwall, potentially creating a local hotspot.
|
|
