The numerical analysis of the three-dimensional (3D) flow over a National Advisory Committee for Aeronautics (NACA) 6321 airfoil to evaluate the mass flow rate by using a novel method Improved Blowing and Suction System (IBSS) to control the boundary layer is presented in this study. Analysis is performed based on 3D Reynolds-Averaged Navier-Stokes (RANS) equation with a K-omega SST solver. The aerodynamic performance of the NACA 6321 is analyzed at a Mach number of 0.10 with three different mass flow rates, namely, 0.08 kg/s, 0.10 kg/s, and 0.12 kg/s. From the study, it is seen that when the mass flow rate decreased, the aerodynamics performance also reduced, and the aerodynamic performance improved with the increase in mass flow rate. Results also show that a mass flow rate of 0.10 kg/s improved the stalling angle of attack (AoA) by 60% and coefficient of lift (CL) by 50%, enabling optimum efficiency of the aircraft wing in all aspects compared to the baseline airfoil model. The mass

Karuppiah, Balaji, Wessley, Jims John

Numerical Analysis of the Influences of Wear on the Vibrations of Power Units

2020-01-150606/03/2020

Numerical Analysis of the Influences of Wear on the Vibrations of Power Units Yashwant Kolluru, Rolando Doelling eBike Department Robert Bosch GmbH Kusterdingen, Germany yashwant.kolluru@de.bosch.com rolando.doelling@de.bosch.com Lars Hedrich Institute of Informatics Goethe University Frankfurt Frankfurt, Germany hedrich@em.informatik.uni-frankfurt.de The prime factor, which influences vibrations of electro-mechanical drives, is wear at the components. This paper discusses the numerical methods developed for abrasion, vibration calculations and the coupling between wear and NVH models of drive unit. Wear is a complex process and understanding it is essential for vibro-acoustics. The paper initially depicts finite element static model used for wear calculations. The special subroutines developed, aids in coupling the wear equations, various contact and friction formulations to the numerical model. The vibration domain model initially, focuses on calculations of mechanical excitation's

Kolluru, Yashwant, Doelling, Rolando, Hedrich, Lars

Minimization of Electric Heating of the Traction Induction Machine Rotor

2020-01-056204/14/2020

The article solves the problem of reducing electric power losses of the traction induction machine rotor to prevent its overheating in nominal and high-load modes. Electric losses of the rotor power are optimized by the stabilization of the main magnetic flow of the electric machine at a nominal level with the amplitude-frequency control in a wide range of speeds and increased loads. The quasi-independent excitation of the induction machine allows us to increase the rigidity of mechanical characteristics, decrease the rotor slip at nominal loads and overloads and significantly decrease electrical losses in the rotor as compared to other control methods. The article considers the technology of converting the power of individual phases into a single energy flow using a three-phase electric machine equivalent circuit and obtaining an energy model in the form of equations of instantaneous active and reactive power balance. The quasi-independent excitation of the induction machine is

Nikiforova, Elena, Smolin, Victor, Gladyshev, Sergey

Mathematical Analysis of Clutch Thermal Energy during Automatic Shifting Coupled with Input Torque Truncation

2020-01-096704/14/2020

A step-ratio automatic transmission alters torque paths for gearshifting through engagement and disengagement of clutches. It enables torque sources to run efficiently while meeting driver demand. Yet, clutch thermal energy during gearshifting is one of the contributors to the overall fuel loss. In order to optimize drivetrain control strategy, including the frequency of shifts, it is important to understand the cost of shift itself. In a power-on upshift, clutch thermal energy is primarily dissipated during inertia phase. The interaction between multiple clutches, coupled with input torque truncation, makes the decomposition of overall energy loss less obvious. This paper systematically presents the mathematical analysis of clutch thermal energy during the inertia phase of a typical single-transition gearshift. In practice, a quicker shift is generally favored, partly because the amount of energy loss is considered smaller. However, the analysis reveals that there is a critical input

Zhang, Yijing, Fujii, Yuji, Hippalgaonkar, Rohit, Cvok, Ivan, Ivanovic, Vladimir, Deur, Josko, Ranogajec, Vanja

Prototype Smartphone App Can Help Parents Detect Early Signs of Eye Disorders in Children

TBMG-3562212/01/2019

A Baylor University researcher’s prototype smartphone app — designed to help parents detect early signs of various eye diseases in their children such as retinoblastoma, an aggressive pediatric eye cancer — has passed its first big test.

Stall Mitigation and Lift Enhancement of NACA 0012 with Triangle-Shaped Surface Protrusion at a Reynolds Number of 10⁵

01-12-02-000711/21/2019

Abstract Transient numerical simulations are conducted over a NACA 0012 airfoil with triangular protrusions at a Reynolds number (Re) of 100000 using the γ-Reθ transition Shear Stress Transport (SST) turbulence model. Protrusions of heights 0.5%c, 1%c, and 2%c are placed at one of the three locations, viz, the leading edge (LE), 5%c on the suction surface, and 5%c on the pressure surface, while the angle of attack (AOA) is varied between 0° and 20°. Results obtained from the time-averaged solution of the unsteady Navier-Stokes equation indicate that the smaller protrusion placed at 5%c on the suction surface improves the post-stall lift coefficient by up to 59%, without altering the pre-stall characteristics. The improvement in time-averaged lift coefficients comes with enhanced flow unsteadiness due to vigorous vortex shedding. For a given protrusion height, the vortex shedding frequency decreases as the AOA is increased, while the amplitude of fluctuations in lift coefficient

Bodavula, Aslesha, Yadav, Rajesh, Guven, Ugur

Development of a CFD Solver for Primary Diesel Jet Atomization in FOAM-Extend

2019-24-012809/09/2019

Ongoing development of a CFD framework for the simulation of primary atomization of a high pressure diesel jet is presented in this work. The numerical model is based on a second order accurate, polyhedral Finite Volume (FV) method implemented in foam-extend-4.1, a community driven fork of the OpenFOAM software. A geometric Volume-of-Fluid (VOF) method isoAdvector is used for interface advection, while the Ghost Fluid Method (GFM) is used to handle the discontinuity of the pressure and the pressure gradient at the interface between the two phases: n-dodecane and air in the combustion chamber. In order to obtain highly resolved interface while minimizing computational time, an Adaptive Grid Refinement (AGR) strategy for arbitrary polyhedral cells is employed in order to refine the parts of the grid near the interface. Dynamic Load Balancing (DLB) is used in order to preserve parallel efficiency during AGR. The combination of isoAdvector-GFM-AGR-DLB presents a unique framework for diesel

Vukcevic, Vuko, Keser, Robert, Jasak, Hrvoje, Battistoni, Michele, Im, Hong, Roenby, Johan

Empirical Investigation on the Effects of Rolling Resistance and Weight on Fuel Economy of Medium-Duty Trucks

02-12-03-001608/28/2019

Abstract Vehicle rolling resistance and weight are two of the factors that affect fuel economy. The vehicle tire rolling resistance has a more significant influence than aerodynamics drags on fuel economy at lower vehicle speeds, particularly true for medium- and heavy-duty trucks. Less vehicle weight reduces inertia loads, uphill grade resistance, and rolling resistance. The influence of weight on the fuel economy can be considerable particularly in light- to medium-duty truck classes because the weight makes up a larger portion of gross vehicle weight. This article presents an empirical investigation and a numerical analysis of the influences of rolling resistance and weight on the fuel economy of medium-duty trucks. The experimental tests include various tires and payloads applied on a total of 21vehicle configurations over three road profiles. These tests assessed the sensitivity of the vehicle’s fuel economy toward rolling resistance and weight. Several experimental results showed

Liao, Gene Y., Card, Brandon, O’Malley, Molly

Numerical Analysis of Blast Protection Improvement of an Armored Vehicle Cab by Composite Armors and Anti-Shock Seats

02-12-01-000112/05/2018

The objective of this article is to evaluate the effects of different blast protective modules to military vehicle structures and occupants. The dynamic responses of the V-shape integral basic armor, the add-on honeycomb sandwich structure module, and the anti-shock seat-dummy system were simulated and analyzed. The improvements of occupant survivability by different protective modules were compared using occupant injury criteria. The integral armored cab can maintain the integrity of the cab body structure. The add-on honeycomb sandwich armor reduces the peak structural deformation and velocity of the cab floor by 34.9% and 47.4%, respectively, compared with the cab with integral armors only. The integral armored cab with the anti-shock seat or the honeycomb sandwich structures reduces the occupant shock responses below the injury criteria. For different blast threat intensities, the selection of appropriate protective modules can meet protection requirements.

Dong, Yan-Peng, Lu, Zhen-Hua

Machine Learning Method Detects Heart Disease

TBMG-3322611/01/2018

Heart disease is the leading cause of death for both men and women, according to the Centers for Disease Control and Prevention (CDC). In the U.S., one in every four deaths is a result of heart disease, which includes a range of conditions from arrhythmias (abnormal heart rhythms) to defects, as well as blood vessel diseases (more commonly known as cardiovascular diseases).

Improvement in DCT Shaft Lubrication through CFD Method

04-11-03-001110/25/2018

Dual-clutch transmission (DCT) output shaft 1 (OS1) mount position is higher than the transmission lubricant level. Needle bearings and idler gears on OS1-insufficient lubrication issues and the transmission lubrication system were investigated. In the design model, the transmission housing lubrication channel and oil guide component design were studied. For numerical analysis, the STAR-CCM+ software was used to simulate transmission internal complex oil-gas multiphase transient flow morphology that monitored the four bore oil churning volumes of OS1. Finally, lubrication test results affirm simulation predictions that idler gears, needle bearings, and synchronizer rings on OS1 obtain sufficient lubrication provided that a reliable method to inspect lubrication design functions is available.

Liu, Hai, Zang, Libin

Passenger Hypoxia Protection Utilizing Oxygen Enriched Gas Mixtures

AIR6036 (Current)10/18/2018

Currently, existing civil aviation standards address the design and certification of oxygen dispensing devices that utilize oxygen sources supplying at least 99.5% oxygen. This Aerospace Information Report discusses issues relating to the use in the passenger cabin of oxygen enriched breathing gas mixtures having an oxygen content of less than 99.5% and describes one method of showing that passenger oxygen dispensing devices provide suitable hypoxia protection when used with such mixtures.

A-10 Aircraft Oxygen Equipment Committee

Investigation of Fatigue Life of Wheels in Commercial Vehicles

02-11-04-001708/21/2018

In India, vehicle population increases every day along with road accidents by 2.5% every year. About 7.7% of accidents are caused by wheel separation, 60% of which are due to nut-related problems. Wheel separations in vehicles occur due to fastener issues and fatigue failures in bolts. A study of the reasons for and mechanisms of nut loosening showed that left-hand side wheels detached and fracture failure occurred in right-hand side studs. Fatigue life of wheels with Nord-Lock washer and without washer is determined by using numerical analysis as per the IS 9438 cornering fatigue test. These numerical results are compared with experimental results.

Bawaskar, Umesh Sadashiv, Awasare, P.

Numerical Prediction of Various Failure Modes in Spotweld Steel Material

09-06-01-000305/11/2018

Crash simulation is targeted mainly carried out by the collision regulations FMVSS simulation to identify problems in vehicle structures. A modern car structure consist of several thousand weld-type connections, and failure in these connections plays an important role for the crashworthiness of the vehicle. Therefore accurate modeling of these connections is important for the automotive industry in order to improve Vehicle collision characteristics. In pursuit of this key requirement, we introduced a proper methodology for the development detailed weld model to study structural response of the weld when the applied load range is beyond the yield strength. Three-dimensional finite element (FE) models of spot welded joints are developed using the LS-Dyna FE code. In this process the force estimation model of spot welds is explained. The results from this paper shows good agreement between the simulations and the tests. Therefore, spot weld model obtained from this study should be

Patil, Sachin, Lankarani, Hamid

A Simulation Model for a Tandem External Gear Pump for Automotive Transmission

2018-01-040304/03/2018

This paper describes a simulation approach for the modeling of tandem external gear pumps. A tandem gear pump is the combination of two pumps with a common drive shaft. Such design architecture finds application in certain automotive transmission systems. The model presented in this work is applicable for pumps with both helical and spur gears. The simulation model is built on the HYGESim (HYdraulic GEars machines Simulator) previously developed by the authors for external spur gear units. In this work, the model formulation is properly extended to the capabilities of simulating helical gears. Starting directly from the CAD drawings of the unit, the fluid-dynamic model solves the internal instantaneous tooth space volume pressures and the internal flows following a lumped parameter approach. The simulation tool considers also the radial micro-motion of the gears, which influences the internal leakages and the features of the meshing process. The paper details how these aspects are

Ransegnola, Thomas M., Vacca, Andrea, Morselli, Mario Antonio, Kowalski, Andrzej, Muizelaar, Richard

Random Vibration Analysis Using Quasi-Random Bootstrapping

2018-01-110404/03/2018

Reliability analysis of engineering structures such as bridges, airplanes, and cars require calculation of small failure probabilities. These probabilities can be calculated using standard Monte Carlo simulation, but this method is impractical for most real-life systems because of its high computational cost. Many studies have focused on reducing the computational cost of a reliability assessment. These include bootstrapping, Separable Monte Carlo, Importance Sampling, and the Combined Approximations. The computational cost can also be reduced using an efficient method for deterministic analysis such as the mode superposition, mode acceleration, and the combined acceleration method. This paper presents and demonstrates a method that uses a combination of Sobol quasi-random sequences and bootstrapping to reduce the number of function calls. The study demonstrates that the use of quasi-random numbers in conjunction bootstrapping reduces dramatically computational cost.

Rahman, Md Asad, Nikolaidis, Efstratios

Efficient Procedure for Robust Optimal Design of Aerospace Laminated Structures

2017-01-205809/19/2017

Innovative aircraft design studies have noted that uncertainty effects could become significant and greatly emphasized during the conceptual design phases due to the scarcity of information about the new aero-structure being designed. The introduction of these effects in design methodologies are strongly recommended in order to perform a consistent evaluation of structural integrity. The benefit to run a Robust Optimization is the opportunity to take into account uncertainties inside the optimization process obtaining a set of robust solutions. A major drawback of performing Robust Multi-Objective Optimization is the computational time required. The proposed research focus on the reduction of the computational time using mathematic and computational techniques. In the paper, a generalized approach to operate a Robust Multi-Objective Optimization (RMOO) for Aerospace structure using MSC software Patran/Nastran to evaluate the Objectives Function, is proposed. A Multi-Objective

Noziglia, Francesco, Rigato, Paolo, Cestino, Enrico, Frulla, Giacomo, Arias-Montano, Alfredo

Application of Structural Topology Optimization to Couple Thin-Walled Stiffened Box-Beams

2017-01-205909/19/2017

Future generations of civil aircrafts and unconventional unmanned configurations demand for innovative structural concepts to improve the structural performance, and thus reduce the structural weight, but also to allow possible material couplings to be made. Static and dynamic aeroelastic stability can be altered by these couplings. It is therefore necessary to use an accurate and computationally efficient beam model during the preliminary design phase. A stiffened box, made of isotropic material, but with the stiffeners oriented so that they originate the expected bending/torsion coupling, is considered in the present work. The overall equivalent bending, torsional and coupled stiffness is derived by means of homogenization of the shell skin and of the stiffener plate stiffness. A new equivalent homogeneous orthotropic material is determined and introduced into the equivalent plate configuration. The accuracy of the simplified beam model is demonstrated by the application of

Cestino, Enrico, Frulla, Giacomo, Duella, Renzo, Piana, Paolo, Pennella, Francesco, Danzi, Francesco

Vibration Analysis of Rotating Tires Focused on Effect of Rotation Using a Three - Dimensional Flexible Ring Model

2017-01-190306/05/2017

The tire is one of the most important parts, which influence the noise, vibration, and harshness of the passenger cars. It is well known that effect of rotation influences tire vibration characteristics, and earlier studies presented formulas of tire vibration behavior. However, there are no studies of tire vibration including lateral vibration on effect of rotation. In this paper, we present new formulas of tire vibration on effect of rotation using a three-dimensional flexible ring model. The model consists of the cylindrical ring represents the tread and the springs represent the sidewall stiffness. The equation of motion of lateral, longitudinal, and radial vibration on the tread are derived based on the assumption of inextensional deformation. Many of the associated numerical parameters are identified from experimental tests. Unlike most studies of flexible ring models, which have mainly discussed radial and circumferential vibration, this study presents eigen functions concerning

Matsubara, Masami, Tsujiuchi, Nobutaka, Ise, Tomohiko, Kawamura, Shozo

Bifurcation Analysis of a Car Model Running on an Even Surface - A Fundamental Study for Addressing Automomous Vehicle Dynamics

2017-01-158903/28/2017

The paper deals with the bifurcation analysis of a simple mathematical model describing an automobile running on an even surface. Bifurcation analysis is adopted as the proper procedure for an in-depth understanding of the stability of steady-state motion of cars (either cornering or running straight ahead). The aim of the paper is providing the fundamental information for inspiring further studies on vehicle dynamics with or without a human driver. The considered mechanical model of the car has two degrees of freedom, nonlinear tire characteristics are included. A simple driver model is introduced. Experimental validations of the model are produced. As a first step, bifurcation analysis is performed without driver (fixed control). Ten different combinations of front and rear tire characteristics (featuring understeer or oversteer automobiles) are considered. Steering angle and speed are varied. Many different dynamical behaviors of the model are found. Homoclinic bifurcations, stable

Mastinu, Giampiero, Della Rossa, Fabio, Gobbi, Massimiliano, Previati, Giorgio

Use of Electric Driveline for a Cooperative Braking Strategy

2017-01-159503/28/2017

This paper presents a brake control strategy with a novel approach to the allocation of actuator effort in an electric vehicle. The proposed strategy relies on a combination of the conventional hydraulic braking system and the electric machine in order to improve braking performance. The higher response frequency of the electric machine is paired with the additional braking torque employed by the hydraulic brakes using an integrated control allocation strategy, which allows for a constant availability of a faster and more accurate modulation of both wheel torque and wheel speed. Therefore, the availability of an electric machine as a fast longitudinal actuator yields to an improved tracking of the desired wheel slip, especially when compared to the hydraulic actuators used in traditional braking applications. As a result, this strategy leads to a clear and considerable reduction of the braking distance, removes the need for a hydraulic modulator and thereby also removes the disturbing

Arat, Mustafa Ali, Duringhof, Hans-Martin, Hagnander, Johan, L. Simoes, Eduardo

Numerical Analysis of the Steady-State Scavenging Flow Characteristics of a Two-Stroke Marine Engine

2017-01-055803/28/2017

The scavenging process in two-stroke marine engines not only transports burnt gas out of the cylinder but also provides fresh air for the next cycle, thereby significantly affecting the engine performance. In order to enhance fuel-air mixing, the scavenging process usually generates swirling flow in uniflow-type scavenging engines. The scavenging stability directly determines the scavenging efficiency and even influences fuel-air mixing, combustion, and emission of the engine. In the present study, a computational fluid dynamics (CFD) analysis of the scavenging process in a steady-state scavenging flow test is conducted. A precession phenomenon is found in the high swirl model, and Proper Orthogonal Decomposition (POD) method is used to analyze the reason and the multi-scale characteristics of the precession phenomenon.

Cui, Lei, Wang, Tianyou, Sun, Kai, Lu, Zhen, Che, Zhizhao, Sun, Yanzhe

Model-Based Circuit Protection Using Solid State Switches

2017-01-164103/28/2017

Currently, circuit breakers and, in most cases, thermal fuses are used for wire protection due to their low cost and robust design. As an alternative, solid state switches are being considered within future electrical distribution systems (EDS) for several reasons, e.g. resetability, diagnosis, smaller tolerances, and reduced dependencies on ambient temperature or arcing. Particularely if combined with benefits on the system level, such an application can be advantageous. The new approach presented in this paper uses a thermal model of the wire instead of only an emulation of the thermal fuse behavior. This allows, based on the electrical current profile, the calculation of the wire temperature and thus a robust and precise protection of the wire. In addition, it minimizes the probability of faulty switching, which is of particular importance with regard to safety-critical electrical functions. Hence, results include higher reliability and a reduction of the wire cross-section area and

Ayeb, Mohamed, Brabetz, Ludwig, Gysen, Leonard

Development of a Fork-Join Dynamic Scheduling Middle-Layer for Automotive Powertrain Control Software

2017-01-162003/28/2017

Multicore microcontrollers are rapidly making their way into the automotive industry. We have adopted the Cilk approach (MIT 1994) to develop a pure ANSI C Fork-Join dynamic scheduling runtime middle-layer with a work-stealing scheduler targeted for automotive multicore embedded systems. This middle-layer could be running on top of any AUTOSAR compliant multicore RTOS. We recently have successfully integrated our runtime layer into parts of legacy Ford powertrain software at Ford Motor Company. We have used the 3-core AURIX multicore chip from Infineon and the multicore RTA-OS. For testing purposes, we have forked some parallelizable functions inside two periodic tasks in Ford legacy powertrain software to be dynamically scheduled and executed on the available cores. Our preliminary evaluation showed 1.3–1.4x speedups for these two forked tasks. It also showed that this runtime layer scales well to the available cores and that it abstracts away the details involved in load balancing

Sadeh, Waseem, Rawashdeh, Osamah, Burkard, Dona, Dobbins, Kelvin, Lockwood, Tony, Bulmus, Atilla

Python Interface to T-Matrix Scattering Computations (PyTMatrix)

TBMG-2546510/01/2016

PyTMatrix is a Python interface to a T-matrix numerical scattering computation code originally developed at NASA GISS (Goddard Institute for Space Studies). It integrates into the NumPy/SciPy scientific framework. The software provides streamlined access to numerical T-matrix computations directly from the Python programming language. It retains the original numerical core written in Fortran 77, thus combining the flexibility of Python and the numerical performance of Fortran. It also provides tools for post-processing the output by integrating over various particle size and orientation distributions.

Numerical Analysis on the Transitional Mechanism of the Wake Structure of the Ahmed Body

2016-01-159204/05/2016

The critical change in drag occurring on the Ahmed body when the slanted base has an angle of 30° is due to a transition in the wake structure. In a previous study on flow analysis across the Ahmed body, we investigated the unsteady wake experimentally using hot-wire and particle image velocimetry measurements. However, because the experimental analysis yielded limited data, the spatially unsteady wake behaviour, interaction between the trailing vortex and transverse vortices (up/downwash), and flow mechanism near the body were not discussed sufficiently. In this study, the unsteady wake structures were analysed computationally using computational fluid dynamics to understand these issues, and the hypothesis was tested. The slant angle was 27.5°, which is identical to that in the experiment and corresponds to a high drag condition indicated experimentally. Spatially unsteady fluctuation structures were clarified, and the relation between the structures and the critical change in drag

Kobayashi, Yuji, Kohri, Itsuhei, Kasai, Akira, Nasu, Takayoshi, Katoh, Daichi, Hashizume, Yoshimitsu

Experimental and Numerical Analysis for a Urea-SCR Catalytic Converter

2016-01-097304/05/2016

Urea-SCR (Selective Catalytic Reduction) systems are getting a lot of attention as the most promising NOx reduction technology for heavy-duty diesel engine exhaust. In order to promote an effective development for an optimal urea-SCR after-treatment system, it is important to clarify the decomposition behavior of the injected urea and a detailed reaction chemistry of the reactants on the catalyst surface in exhaust gases. In this paper we discuss experimental and numerical studies for the development of a numerical simulation model for the urea-SCR catalyst converter. As a first step, in order to clarify the behavior of reductants in an urea-SCR converter, two types of diagnostic technique were developed; one is for measuring the amount of NH3, and the other is for measuring the amount of total reductants including unreacted urea and iso-cyanic acid. These techniques were applied to examine the behavior of reductants at the inlet and inside the SCR converter. This revealed i) urea to

Yamauchi, Takafumi, Takatori, Yoshiki, Fukuda, Koichiro, Maruyama, Masatoshi

Gravitational Compensation Onboard a Comsat

TBMG-23260

11/01/2015

This technique for compensating the gravitational attraction experienced by a test-mass freely floating onboard a satellite is new, and solves an important problem that all gravitational wave missions face. Its application to the geostationary Laser Interferometer Space Antenna (gLISA) mission concept addresses and completely solves an important noise source: the gravity-gradient noise.

Numerical Investigation of Streamwise Vortex Interaction

2015-01-257309/15/2015

Streamwise vortices can be observed to interact in a number of real world scenarios. Vortex generators operating in boundary layers, as well as aircraft flying in formation can produce vortex interactions with multiple streamwise vortices in close proximity to each other. The tracking of these vortex paths as well as the location and nature of their breakdown is critical to determining how the structures can be used to aid flow control, and how large scale turbulence develops from them. Six configurations of two NACA0012 vanes were evaluated computationally to observe the interactions of a pre-existing vortex with a vortex generated downstream. Co and counter-rotating configurations at three different lateral spacings were used to vary vortex position and impingement on the rear vane. RANS testing of all configurations revealed that the strength of the downstream vortex in the co-rotating case was largely unaffected by the presence of the upstream vortex, while the counter-rotating

Forster, Kyle J., Barber, Tracie, Diasinos, Sammy, Doig, Graham

An Efficient Algorithm for Solving Differential Equations to Facilitate Modeling and Simulation of Aerospace Systems

2015-01-240209/15/2015

Differential equations play a prominent role in aerospace engineering by modeling aerospace structures, describing important phenomena, and simulating mathematical behavior of aerospace dynamical systems. Presently, aerospace systems have become more complex, space vehicle missions require more hours of simulation time to complete a maneuver, and high-performance missiles require more logical decisions in there phases of flight. Because of these conditions, a computationally efficient algorithm for solving these differential equations is highly demanded to significantly reduce the computing time. This paper presents an efficient method for solving the differential equations by using variational iteration method, which can be implemented into software package to dramatically reduce the computing time for simulating the aerospace systems thereby significantly improving computer's performance in real-time design and simulation of aircrafts, spacecrafts, and other aerospace vehicles.

Liu, Yucheng

Numerical Investigation of the Effect of Microchannel Evaporator Design on the Performance of Two-Phase Ejector Automotive Air Conditioning Cycles

2015-01-036204/14/2015

Much attention has been given in recent years to the use of two-phase ejectors and particularly to the performance of the standard ejector cycle with a liquid-vapor separator. However, this cycle may not be the best choice for automotive applications due to the large size required by an efficient separator as well as the cycle's performance at conditions of lower ejector potential. A limited amount of recent research has focused on alternate two-phase ejector cycles that may be better suited for automotive applications. One of these cycles, using the ejector to allow for evaporation at two different temperatures and eliminating the need for a separator, will be the subject of investigation in this paper. Previous investigations of this cycle have been mainly theoretical or experimental; this paper aims to provide a numerical analysis of the effect of evaporator design on the performance of the ejector cycles. In this paper, a numerical model of a microchannel evaporator is developed

Lawrence, Neal, Elbel, Stefan

Interval Finite Element Analysis of Structural Dynamic Problems

2015-01-048404/14/2015

We analyze the frequency response of structural dynamic systems with uncertainties in load and material properties. We introduce uncertainties in the system as interval numbers, and use Interval Finite Element Method (IFEM). Overestimation due to dependency is reduced using a new decomposition for the stiffness and mass matrices, as well as for the nodal equivalent load. In addition, primary and derived quantities are simultaneously obtained by means of Lagrangian multipliers that are introduced in the total energy of the system. The obtained interval equations are solved by means of a new variant of the iterative enclosure method resulting in guaranteed enclosures of relevant quantities. Several numerical examples show the accuracy and efficiency of the new formulation.

Xiao, Naijia, Muhanna, Rafi L., Fedele, Francesco, Mullen, Robert L.

Uncertainty Analysis of Static Plane Problems by Intervals

2015-01-048204/14/2015

We present a new interval-based formulation for the static analysis of plane stress/strain problems with uncertain parameters in load, material and geometry. We exploit the Interval Finite Element Method (IFEM) to model uncertainties in the system. Overestimation due to dependency among interval variables is reduced using a new decomposition strategy for the structural stiffness matrix and the nodal equivalent load vector. Primary and derived quantities follow from minimization of the total energy and they are solved simultaneously and with the same accuracy by means of Lagrangian multipliers. Two different element assembly strategies are introduced in the formulation: one is Element-by-Element, and the other resembles conventional assembly. In addition, we implement a new variant of the interval iterative enclosure method to obtain outer and inner solutions. Numerical examples show that the proposed interval approach guarantees to enclose the exact system response.

Xiao, Naijia, Muhanna, Rafi L., Fedele, Francesco, Mullen, Robert L.

Road Profile Estimation for Active Suspension Applications

2015-01-065104/14/2015

The road profile has been shown to have significant effects on various vehicle conditions including ride, handling, fatigue or even energy efficiency; as a result it has become a variable of interest in the design and control of numerous vehicle parts. In this study, an integrated state estimation algorithm is proposed that can provide continuous information on road elevation and profile variations, primarily to be used in active suspension controls. A novel tire instrumentation technology (smart tire) is adopted together with a sensor couple of wheel attached accelerometer and suspension deflection sensor as observer inputs. The algorithm utilizes an adaptive Kalman filter (AKF) structure that provides the sprung and unsprung mass displacements to a sliding-mode differentiator, which then yields to the estimation of road elevations and the corresponding road profile along with the quarter car states. The proposed method is tested through numerical analysis under MATLAB/Simulink

Arat, Mustafa Ali, Taheri, Saied, Holweg, Edward

An Efficient Method to Calculate the Failure Rate of Dynamic Systems with Random Parameters Using the Total Probability Theorem

2015-01-042504/14/2015

Using the total probability theorem, we propose a method to calculate the failure rate of a linear vibratory system with random parameters excited by stationary Gaussian processes. The response of such a system is non-stationary because of the randomness of the input parameters. A space-filling design, such as optimal symmetric Latin hypercube sampling or maximin, is first used to sample the input parameter space. For each design point, the output process is stationary and Gaussian. We present two approaches to calculate the corresponding conditional probability of failure. A Kriging metamodel is then created between the input parameters and the output conditional probabilities allowing us to estimate the conditional probabilities for any set of input parameters. The total probability theorem is finally applied to calculate the time-dependent probability of failure and the failure rate of the dynamic system. The proposed method is demonstrated using a vibratory system. Our approach can

Majcher, Monica, Mourelatos, Zissimos P., Geroulas, Vasileios, Baseski, Igor, Singh, Amandeep

A Data Mining-Based Strategy for Direct Multidisciplinary Optimization

2015-01-047904/14/2015

One of the major challenges in multiobjective, multidisciplinary design optimization (MDO) is the long computational time required in evaluating the new designs' performances. To shorten the cycle time of product design, a data mining-based strategy is developed to improve the efficiency of heuristic optimization algorithms. Based on the historical information of the optimization process, clustering and classification techniques are employed to identify and eliminate the low quality and repetitive designs before operating the time-consuming design evaluations. The proposed method improves design performances within the same computation budget. Two case studies, one mathematical benchmark problem and one vehicle side impact design problem, are conducted as demonstration.

Xu, Hongyi, Chuang, Ching-Hung, Yang, Ren-Jye

Reducing Power-On/Off Glitches in Precision DACs: Part 2

TBMG-21943

04/10/2015

introduced a phenomenon called power-on/off glitch. The example discussed the impact of this phenomenon on a motor control system. We limited our analysis to a DAC where the output buffer is powered on in normal mode: zero-scale or mid-scale. In Part 2, we analyze when the DAC output is powered on in high-impedance mode. We present a mathematical model for the power-on glitch, followed by board-level solutions to minimize it.

Numerical Analysis of Flow Field Parameters in Internal Combustion Engines with Experimental Validation

2014-36-037109/30/2014

The simulation of the fluid dynamics in internal combustion engines has become more important in the past few years for research, development and design of that equipment. The Computational Fluid Dynamics (CFD) methodology is able to analyze the fluid flow in regions the experimental technology cannot afford to. Using a single cylinder research engine, the calculation can be validated from in-cylinder pressure and temperature measurements, also with velocity fields and the related variables. This paper presents the evaluation of the numerical results for tumble and swirl coefficient on internal combustion engines along with its validation. The commercial code STAR-CD, with the ES-ICE module, specific for internal combustion engine, was used for the CFD calculation. Grid independence studies in space and time has been made for reliability of the results. The results show a motor optimized for the tumble and swirl coefficients having its maximum values around the spark time, thus it

Fonseca, Leonardo Guimarães, de Oliveira Alvarenga Coelho, Raniro, Braga, Raphael Meireles, Valle, Ramon Molina

Implementing Determinate Assembly for the Leading Edge Sub-Assembly of Aircraft Wing Manufacture

2014-01-225209/16/2014

The replacement for the current single-aisle aircraft will need to be manufactured at a rate significantly higher that of current production. One way that production rate can be increased is by reducing the processing time for assembly operations. This paper presents research that was applied to the build philosophy of the leading edge of a laminar flow European wing demonstrator. The paper describes the implementation of determinate assembly for the rib to bracket assembly interface. By optimising the diametric and the positional tolerances of the holes on the two bracket types and ribs, determinate assembly was successfully implemented. The bracket to rib interface is now secured with no tooling or post processes other than inserting and tightening the fastener. This will reduce the tooling costs and eliminates the need for local drilling, de-burring and re-assembly of the bracket to rib interface, reducing the cycle time of the operation. Ultimately, self-indexing components mean

Irving, Lucas, Ratchev, Svetan, Popov, Atanas, Rafla, Marcus

Design Analysis for Origami-Based Folded Sheet Metal Parts

2014-01-909804/20/2014

1 The manufacturing of Origami based sheet metal products is a promising technology, mostly in terms of reducing the tooling and process complexity. This procedure can also be called fold forming, as it depends on exclusively shaping the required geometry via sequence of bends. However, the design analysis and modeling of folded sheet metal products are not fully mature, especially in terms of determining the best approach for transferring the analysis from a three-dimensional (3D) to a two-dimensional (2D) context. This manuscript discusses the extension of the Origami technique to the fold forming of sheet metal products represented in modeling approach and design considerations for the topological variations, the geometrical validity, and the variance of stress-based performance. This paper also details the optimization metrics that were developed to reflect the design and manufacturing differences among the possible topological and geometrical options for a single part design

Qattawi, Ala, Abdelhamid, Mahmoud, Mayyas, Ahmad, Omar, Mohammed

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