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Focus on Challenges in SLD Regime: Reemitted Droplet Modelling

Dassault Aviation-Francois Caminade, Loïc Frazza
Published 2019-06-10 by SAE International in United States
A lot of studies have been carried out over the last decades on SLD ice accretion challenges. Many of them referred to SLD physics modelling such as break-up, splashing, bouncing, etc… and relied on numerous physics experiments. Different models have been developed in Europe and North-America and have been implemented in several numerical tools, widely in 2D but more and more in 3D. As these tools are intended to be used increasingly among the community, deficiencies have to be deeper investigated. This paper provides some highlights on specific needs linked to SLD impingement and ice accretion, especially for 3D high fidelity computations. Regarding the results, deficiencies on the numerical side and on experimental needs will be highlighted in order to feed brainstorming for ongoing SLD projects such as in European Union H2020 ICE-GENESIS.
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Experimental and Computer Model Results for a Carbon Nanotubes Electrothermal De-Icing System

Embraer-Rodrigo Domingos, Gilberto Becker
Published 2019-06-10 by SAE International in United States
Results from a three-dimensional computer model of a Carbon Nanotubes (CNT) based de-icing system are compared to experimental data obtained at COLLINS-Ohio Icing Wind Tunnel (IWT). The experiments were performed using a prototype of a CNT based de-icing system installed in a section of a business jet horizontal tail. The 3D numerical analysis tools used in the comparisons are AIPAC [1] and CFD++. The former was derived from HASPAC, an anti-icing computer model developed at Wichita State University in 2010 [3, 9, 10]. AIPAC uses the finite volumes method for the solution of the icing problem on an airfoil leading edge (or other 3D surfaces) and relies on any CFD solver to obtain the external flow properties used as boundary conditions. AIPAC is capable of predicting 3D multi-step ice shapes under rime, glaze and mixed regimes, and can also deal with the complex dynamics of cyclic ice accretion, melting, and shedding present in the realm of aircraft electrothermal de-icing systems. The latter is the CFD solver selected to provide the external flow properties for the…
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Computational Simulation of an Electrically Heated Ice Protection System for Composite Leading Edges of Aircraft

Gyeongsang National University-Prince Raj Lawrence Raj, Hojin Jeong, Rene Roy, Jin-Hwe Kweon, Rho Shin Myong
Published 2019-06-10 by SAE International in United States
The performance of an electrically heated aircraft ice protection system for a composite leading edge was evaluated. The composite leading edge of the model is equipped with a Ni alloy resistance heater. A state-of-the-art icing code, FENSAP-ICE, was used for the analysis of the electrothermal de-icing system. Computational results, including detailed information of conjugate heat transfer, were validated with experimental data. The computational model was then applied to the composite leading edge wing section at various metrological conditions selected from FAR Part 25 Appendix C.
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Vibroacoustic Model’s Likelihood Computation Based on a Statistical Reduction of Random FRF Matrices

PSA Group-Laurent Gagliardini, Justin Reyes
Université Paris-Est-Christian Soize
Published 2019-06-05 by SAE International in United States
Improvement of vibroacoustic models prediction capabilities requires an adapted indicator to compare experimental measurements with the results of the computational model. When dealing with highly uncertain objects such as series production cars, a probabilistic approach is mandatory to be able to describe the dispersion of experimental results. Moreover, a probabilistic non-parametric model also account for modeling uncertainties and simplifications that are part of any engineering process. The proposed approach deals with Frequency Response Functions since FRFs are the common way to handle vibroacoustic models. When considering multiple input and output points configuration, FRFs are frequency dependent complex matrices. Since the probabilistic modeling is available in current vibroacoustic software, collections of random realizations of the FRF matrix can be computed from the existing FE model. The model’s likelihood naturally appears as the probability of a measured quantity to be part of its model. It is a single number that can advantageously be used as an indicator of the model‘s relevance regarding measurements. A novel complex FRF matrix statistical reduction is proposed, allowing the model’s likelihood computation.…
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Drivetrain Noise Source Identification and Active Noise Control of a Heavy Off-Road Vehicle

Dongfeng Motor Technical Center-Zuguo Xia
Gissing Tech. Co., Ltd.-Hailin Ruan, Wei Huang, Longchen Li, Xiaojun Chen, Xiujie Tian, Keda Zhu, Changwei Zheng, Jiapeng Zhao, Renjie Dai
Published 2019-06-05 by SAE International in United States
Drivetrain noise from heavy off-road vehicles mainly includes engine noise, drive shaft noise, wheel-side gear noise, tire pattern noise etc. They are the main noise sources for such vehicles as they greatly influence the ride comfort of the passengers inside. This paper solved the drivetrain noise problems of a heavy off-road vehicle using the method of active noise control (ANC). Firstly, the vehicle is benchmarked and the noise problems are analyzed, while the noise sources are identified by analyzing the transmission principles of the drivetrain. Secondly, ANC strategies are made for the vehicle based on the noise profiles under various operating conditions. Thirdly, the multiple parameters for ANC are computed from simulations modeling the vehicle in idle, constant speed and acceleration respectively. Lastly, road tests are conducted using the multiple parameters from the simulations and a noise reduction of 2-4 dB can be achieved in the whole vehicle. The results has shown that ANC is an effective method for drivetrain noise reduction in heavy off-road vehicles as this paper provides references for the systematic solution…
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Effectiveness of Power-Law Profile Indentations on Structure-Borne Noise

General Motors-Jeffrey Curtis
General Motors Technical Center India-Pranoy Sureshbabu Nair, Nilankan Karmakar, Seshagiri Rao Maddipati
Published 2019-06-05 by SAE International in United States
A study on the effect of indenting power-law shaped profiles on the flexible structures for investigating the vibration damping characteristics using computational simulation method is discussed. The simulation results are checked to see the impact of such features on the damping behavior of flexible structures responsible for radiating noise when excited with fluctuating loads. Though the conventional remedies for solving Noise and vibration issues generally involves tuning of structure stiffness or damping treatment this paper gives an insight on the idea of manipulation of elastic waves within the flexible structure itself to minimize the cross-reflections of the mechanical waves. The simulation studies mentioned in this paper not only hovers over the effectiveness of such features but also will be helpful for the engineers to look through a different perspective while solving N&V issues using simulation tools. In this paper, different studies are discussed to see the impact of such features on the damping effect of the vibrating structure comparing mobility response and far-field sound pressure response as well. Propagation of waves within the structure is…
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Materials and Process Modeling of Aerospace Composites

Charles Lu
  • Progress In Technology (PT)
  • PT-202
Published 2019-04-30 by SAE International in United States
Since the successful production of carbon fibers in early 1960s, composite materials have emerged as the materials of choice for general aviation aircraft, military aircraft, space launch vehicles, and unmanned air vehicles. This has revolutionized the aerospace industry due to their excellent mechanical and physical properties, as well as weight-reducing ability. The next- generation material development model should operate in an integrated computational environment, where new material development, manufacturability, and product design practice are seamlessly interconnected. Materials and Process Modeling of Aerospace Composites reports recent developments on materials and processes of aerospace composites by using computational modeling, covering the following aspects: • The historical uses of composites in aerospace industry, documenting in detail the early usage of composite materials on Premier I by Raytheon to recent full-scale applications of composites on large commercial aircraft by Boeing and Airbus. • An overview on the classifications of composites used in aerospace industry, ranging from conventional glass- fiber reinforced composites to advanced graphene nanocomposites. • The recent work on computational material engineering on aerospace composite materials, including fundamental…
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Systematic CFD Parameter Approach to Improve Torque Converter Simulation

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Motor Co., USA-Steve Frait
Michigan Technological University, USA-Edward De Jesus Rivera, Darrell L. Robinette, Jason R. Blough, Carl L. Anderson
  • Journal Article
  • 06-12-02-0008
Published 2019-04-08 by SAE International in United States
A systematic parametrization approach was employed to simulate a torque converter operating over a wide range of speed ratios. Results of the simulation yielded torque converter impeller and turbine torques prediction errors below 11% when compared to manufacturer data. Further improvements in the computational fluids dynamic (CFD) model reduced such errors down to 3% for the impeller and 6% for the turbine torque predictions. Convergence was reached well under 300 iterations for the most optimal variable setting, but each speed ratio was let to run for 300 iterations. Solution time for the 300 iterations was 40 minutes per speed ratio. The systematic parametrization provides a very competitive procedure for torque converter simulation with reduced computational error and fast solution time.
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Accuracy and Sensitivity of Yaw Speed Analysis to Available Data

MEA Forensic Engineers & Scientists-Bradley Heinrichs, Janice Lee, Cole Young
Published 2019-04-02 by SAE International in United States
Accident reconstructionists rarely have complete data with which to determine vehicle speed, and so the true value must be bracketed within a range. Previous work has shown the effect of friction uncertainty in determining speed from tire marks left by a vehicle in yaw. The goal of the current study was to assess improvements in the accuracy of vehicle speed estimated from yaw marks using progressively more scene and vehicle information. Data for this analysis came from staged S-turn maneuvers that in some cases led to rollover of sport utility vehicles. Initial speeds were first calculated using the critical curve speed (CCS) formula on the yaw marks from the first portion of the S-maneuver. Then computer simulations were performed with progressively more input data: i) the complete tire marks from the whole S-maneuver, ii) measured vehicle mass, iii) measured suspension stiffness and damping, and iv) measured steering history. Simulations based on the complete tire marks reduced the average error compared with the CCS equation if measured accelerations were also matched. Adding the remaining input data…
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A Visual Investigation of CFD-Predicted In-Cylinder Mechanisms That Control First- and Second-Stage Ignition in Diesel Jets

Sandia National Laboratories-Mark Musculus
University of Wisconsin-Rolf Reitz
Published 2019-04-02 by SAE International in United States
The long-term goal of this work is to develop a conceptual model for multiple injections of diesel jets. The current work contributes to that effort by performing a detailed modeling investigation into mechanisms that are predicted to control 1st and 2nd stage ignition in single-pulse diesel (n-dodecane) jets under different conditions. One condition produces a jet with negative ignition dwell that is dominated by mixing-controlled heat release, and the other, a jet with positive ignition dwell and dominated by premixed heat release.During 1st stage ignition, fuel is predicted to burn similarly under both conditions; far upstream, gases at the radial-edge of the jet, where gas temperatures are hotter, partially react and reactions continue as gases flow downstream. Once beyond the point of complete fuel evaporation, near-axis gases are no longer cooled by the evaporation process and 1st stage ignition transitions to 2nd stage ignition. At this point, for the positive ignition dwell case, all of the fuel has already been injected and the 2nd stage ignition zone is surrounded by a relatively large mass of…
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