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Technical Paper
2014-04-01
Chenaniah Langness, Michael Mangus, Christopher Depcik
Abstract In order to perform cutting-edge engine research that applies to modern Compression Ignition (CI) engines, a sophisticated test cell is needed that allows control of the engine and its auxiliary systems. The primary obstacle to the completion of such a test cell is the up-front expense. This paper covers the construction of a low cost, single-cylinder engine test cell while demonstrating the type of research that can be accomplished along the way. The components necessary for the construction, instrumentation, and operation of such a test cell, neglecting emissions analysis equipment, can be obtained for less than $150,000. The engine utilized, a naturally-aspirated single-cylinder Yanmar L100V, was purchased as an engine-generator package. Major upgrades to the engine include an Alternating Current (AC) dynamometer, a Variable-Geometry Turbocharger (VGT), a gaseous-additive fuel injection system, external cooled Exhaust Gas Recirculation (EGR), in-cylinder pressure measurement, and an electronically controlled common-rail fuel injection system.
Technical Paper
2014-04-01
Kenji Tadakuma, Takashi Sugiyama, Kazuhiro Maeda, Masashi Iyota, Masahiro Ohta, Yoshinao Komatsu
A new wind tunnel was developed and adopted by Toyota Motor Corporation in March 2013. This wind tunnel is equipped with a 5-belt rolling road system with a platform balance that enables the flow simulation under the floor and around the tires in on-road conditions. It also minimizes the characteristic pulsation that occurs in wind tunnels to enable the evaluation of unsteady aerodynamic performance aspects. This paper describes the technology developed for this new wind tunnel and its performance verification results. In addition, after verifying the stand-alone performance of the wind tunnel, a vehicle was placed in the tunnel to verify the utility of the wind tunnel performance. Tests simulated flow fields around the vehicle in on-road conditions and confirmed that the wind tunnel is capable of evaluating unsteady flows.
Technical Paper
2014-04-01
Kevin R. Cooper, Miroslav Mokry
Abstract The solid-wall wind tunnel boundary correction method outlined in this paper is an efficient pressure-signature method that requires few wall-mounted pressures. These pressures are used to determine the strengths of model- and wake-representing singularities that are used with the method of images to calculate the longitudinal and lateral velocity increments induced by the wind tunnel walls. Two force correction models are presented that convert these velocity increments to force and moment corrections. The performances of the correction procedures are demonstrated by their application to data from two sets of four, geometrically identical, differently sized, simplified automotive models.
Technical Paper
2014-04-01
Daichi Katoh, Kensuke Koremoto, Munetsugu Kaneko, Yoshimitsu Hashizume
An air-dam spoiler is commonly used to reduce aerodynamic drag in production vehicles. However, it inexplicably tends to show different performances between wind tunnel and coast-down tests. Neither the reason nor the mechanism has been clarified. We previously reported that an air-dam spoiler contributed to a change in the wake structure behind a vehicle. In this study, to clarify the mechanism, we investigated the coefficient of aerodynamic drag CD reduction effect, wake structure, and underflow under different boundary layer conditions by conducting wind tunnel tests with a rolling road system and constant speed on-road tests. We found that the air-dam spoiler changed the wake structure by deceleration of the underflow under stationary floor conditions. Accordingly, the base pressure was recovered by approximately 30% and, the CD value reduction effect was approximately 10%. The ratio of the base pressure recovery to the CD value reduction effect was approximately 90%, suggesting that the main mechanism is the base pressure recovery produced by changing the wake structure.
Technical Paper
2014-04-01
Michael Guerrero, Kapil Butala, Ravi Tangirala, Amy Klinkenberger
NHTSA has been investigating a new test mode in which a research moving deformable barrier (RMDB) impacts a stationary vehicle at 90.1 kph, a 15 degree angle, and a 35% vehicle overlap. The test utilizes the THOR NT with modification kit (THOR) dummy positioned in both the driver and passenger seats. This paper compares the behavior of the THOR and Hybrid III dummies during this oblique research test mode. A series of four full vehicle oblique impact crash tests were performed. Two tests were equipped with THOR dummies and two tests were equipped with Hybrid III dummies. All dummies represent 50th percentile males and were positioned in the vehicle according to the FMVSS208 procedure. The Hybrid III dummies were instrumented with the Nine Accelerometer Package (NAP) to calculate brain injury criteria (BrIC) as well as THOR-Lx lower legs. Injury responses were recorded for each dummy during the event. High speed cameras were used to capture vehicle and dummy kinematics. The vehicle restraint devices and their associated deployment times remained the same for each test.
Technical Paper
2014-04-01
Gerhard Wickern
Abstract Open jet wind tunnels are normally tuned to measure “correct” results without any modifications to the raw data. This is an important difference to closed wall wind tunnels, which usually require wind tunnel corrections. The tuning of open jet facilities is typically done experimentally using pilot tunnels and adding final adjustments in the commissioning phase of the full scale tunnel. This approach lacked theoretical background in the past. There is still a common belief outside the small group of people designing and using open jet wind tunnels, that - similar to closed wind tunnels, which generally measure too high aerodynamic forces and moments without correction - open jet wind tunnels measure coefficient too low compared to the real world. The paper will try to show that there is a solid physical foundation underlying the experimental approach and that the expectation to receive self-correcting behavior can be supported by theoretical models. During the past years an improved understanding of test section interference in open jet wind tunnels has been developed.
Technical Paper
2014-04-01
Oliver Mankowski, David Sims-Williams, Robert Dominy
This paper outlines the creation of a facility for simulating on-road transients in a model scale, ¾ open jet, wind tunnel. Aerodynamic transients experienced on-road can be important in relation to a number of attributes including vehicle handling and aeroacoustics. The objective is to develop vehicles which are robust to the range of conditions that they will experience. In general it is cross wind transients that are of greatest significance for road vehicles. On-road transients include a range of length scales but the most important scales are in the in the 2-20 vehicle length range where there are significant levels of unsteadiness experienced, the admittance is likely to be high, and the reduced frequencies are in a band where a dynamic test is required to correctly determine vehicle response. Based on measurements of on-road conditions, the aim was for the turbulence generation system to achieve yaw angles up to 6-8°, equating to a lateral turbulence intensity of 8-10% with a frequency range extending up to 10 Hz.
Technical Paper
2014-04-01
Dirk Wieser, Hanns-Joachim Schmidt, Stefan Müller, Christoph Strangfeld, Christian Nayeri, Christian Paschereit
The experimental investigation was conducted with a 25%-scaled realistic car model called “DrivAer” mounted in a wind tunnel. This model includes geometric elements of a BMW 3 series and an Audi A4, accommodating modular, rear-end geometries so that it represents a generalized modern production car. The measurements were done with two different DrivAer rear end configurations (fastback and notchback) at varying side-wind conditions and a Reynolds number of up to Re=3.2·106. An array of more than 300 pressure ports distributed over the entire rear section measured the temporal pressure distribution. Additionally, extensive flow visualizations were conducted. The combination of flow visualization, and spatially and temporally resolved surface pressure measurements enables a deep insight into the flow field characteristics and underlying mechanisms. Moreover, static pressure fluctuations indicate regions with a high turbulence level due to flow separation and interaction between different vortical structures.
Technical Paper
2014-04-01
Sofie Koitrand, Lennart Lofdahl, Sven Rehnberg, Adrian Gaylard
Automotive aerodynamics measurements and simulations now routinely use a moving ground and rotating wheels (MVG&RW), which is more representative of on-road conditions than the fixed ground-fixed wheel (FG&FW) alternative. This can be understood as a combination of three elements: (a) moving ground (MVG), (b) rotating front wheels (RWF) and (c) rotating rear wheels (RWR). The interaction of these elements with the flow field has been explored to date by mainly experimental means. This paper presents a mainly computational (CFD) investigation of the effect of RWF and RWR, in combination with MVG, on the flow field around a saloon vehicle. The influence of MVG&RW is presented both in terms of a combined change from a FG&FW baseline and the incremental effects seen by the addition of each element separately. For this vehicle, noticeable decrease in both drag and rear lift is shown when adding MVG&RW, whereas front lift shows little change. The same trends are seen in both CFD and experimental data.
Technical Paper
2014-04-01
Austin Hausmann, Christopher Depcik
This study investigates the practicality of vehicle coast down testing as a suitable replacement to moving floor wind tunnel experimentation. The recent implementation of full-scale moving floor wind tunnels is forcing a re-estimation of previous coefficient of drag determinations. Moreover, these wind tunnels are relatively expensive to build and operate and may not capture concepts such as linear and quadratic velocity dependency along with the influence of tire pressure on rolling resistance. As a result, the method elucidated here improves the accuracy of the fundamental vehicle modeling equations while remaining relatively affordable. The trends produced by incorporating on road test data into the model fit the values indicated by laboratory tests. This research chose equipment based on a balance between affordability and accuracy while illustrating that higher resolution frequency equipment would further enhance the model accuracy.
WIP Standard
2014-03-31
This SAE Aerospace Standard (AS) provides a method for gas turbine engine performance computer programs to be written using FORTRAN COMMON blocks. If a "function-call application program interface" (API) is to be used, then ARP4868 and ARP5571 are recommended as alternatives to that described in this document. When it is agreed between the program user and supplier that a particular program shall be supplied in FORTRAN, this document shall be used in conjunction with AS681 for steady-state and transient programs. This document also describes how to take advantage of the FORTRAN CHARACTER storage to extend the information interface between the calling program and the engine subroutine.
WIP Standard
2014-03-26
1.1 This SAE Aerospace Standard (AS) provides performance station designation and nomenclature systems for aircraft propulsion systems and their derivatives. 1.2 The parameter naming conventions presented herein are for use in all communications concerning propulsion system performance such as computer programs, data reduction, design activities, and published documents. They are intended to facilitate calculations by the program user without unduly restricting the method of calculation used by the program supplier. 1.3 The list of symbols presented herein will be used for identification of input and output parameters. These symbols are not required to be used as internal parameter names within the engine subprogram
WIP Standard
2014-03-26
This SAE Aerospace Standard (AS) provides performance station designation and nomenclature systems for aircraft propulsion systems and their derivatives. The systems presented herein are for use in all communications concerning propulsion system performance such as computer programs, data reduction, design activities, and published documents. They are intended to facilitate calculations by the program user without unduly restricting the method of calculation used by the program supplier. The list of symbols presented herein will be used for identification of input and output parameters. These symbols are not required to be used as internal parameter names within the engine subprogram.
WIP Standard
2014-02-24
"Hot Day ", "Tropical Day ", "Standard Day ", "Polar Day " and "Cold Day " are part of the lexicon of the aircraft industry. These terms are generally understood to refer to specific, generally accepted characteristics of atmospheric temperature versus pressure altitude. There are also other, less well-known days, defined by their frequency of occurrence, such as "1% Hot Day ", "10% Cold Day ", or "Highest Recorded Day ". These temperature characteristics have their origins in multiple sources, including U.S. military specifications which are no longer in force.
Standard
2014-02-21
“Hot Day”, “Tropical Day”, “Standard Day”, “Polar Day”, and “Cold Day” are part of the lexicon of the aircraft industry. These terms are generally understood to refer to specific, generally accepted characteristics of atmospheric temperature versus pressure altitude. There are also other, less well-known days, defined by their frequency of occurrence, such as “1% Hot Day”, “10% Cold Day”, or “Highest Recorded Day”. These temperature characteristics have their origins in multiple sources, including U.S. military specifications which are no longer in force.
Standard
2014-02-13
This SAE Aerospace Recommended Practice (ARP) provides performance station designation and nomenclature systems for aircraft propulsion systems and their derivatives. The systems presented herein are for use in all communications concerning propulsion system performance such as computer programs, data reduction, design activities, and published documents.
Standard
2014-01-03
This SAE Aerospace Standard (AS) provides performance station designation and nomenclature systems for aircraft propulsion systems and their derivatives. The systems presented herein are for use in all communications concerning propulsion system performance such as computer programs, data reduction, design activities, and published documents. They are intended to facilitate calculations by the program user without unduly restricting the method of calculation used by the program supplier. The list of symbols presented herein will be used for identification of input and output parameters. These symbols are not required to be used as internal parameter names within the engine subprogram.
WIP Standard
2013-10-19
The SAE Aerospace Standard document AS681 is the parent document of this SAE Aerospace Recommended Practice (ARP). AS681 applies to Engine programs written to conform to this document. This ARP specifies a set of functions and their expected behaviors that constitute a function based Application Program Interface (API) for gas turbine engine customer programs. The functions specified in this API are delivered by the Supplier as part of the Engine model. This document defines generic language independent functions and specific appendices for implementations in C and Fortran. The function based API specified in this ARP represents an alternative to the Fortran COMMON block structure, as specified in AS4191, historically used to communicate with an engine program. The customer may request emulation of the AS4191 interface if desired. This document does not specify how the parameter names in the Engine program are constructed, how program capabilities might be expanded or altered, or how error messages are constructed.
WIP Standard
2013-10-18
This document provides recommendations for several aspects of air-breathing gas turbine engine performance modeling using object-oriented programming systems. Nomenclature, application program interface, and user interface are addressed with the emphasis on nomenclature. The Numerical Propulsion System Simulation (NPSS) modeling environment is frequently used in this document as an archetype. Many of the recommendations for standards are derived from NPSS standards. NPSS was chosen because it is an available product. The practices recommended herein may be applied to other object-oriented systems. While this document applies broadly to any gas turbine engine, the great majority of engine performance computer programs have historically been written for aircraft propulsion systems. Aircraft and propulsion terminology and examples appear throughout.
Standard
2013-10-04
This document provides recommendations for several aspects of air-breathing gas turbine engine performance modeling using object-oriented programming systems. Nomenclature, application program interface, and user interface are addressed with the emphasis on nomenclature. The Numerical Propulsion System Simulation (NPSS) modeling environment is frequently used in this document as an archetype. Many of the recommendations for standards are derived from NPSS standards. NPSS was chosen because it is an available product. The practices recommended herein may be applied to other object-oriented systems. While this document applies broadly to any gas turbine engine, the great majority of engine performance computer programs have historically been written for aircraft propulsion systems. Aircraft and propulsion terminology and examples appear throughout.
Technical Paper
2013-09-17
Alessandro Ceruti, Piergiovanni Marzocca, Casey Stockbridge
Scaled models are often used to check the aerodynamic performance of full scale aircraft and airship concepts, which have gone through a conceptual and preliminary design process. Results from these tests can be quite useful to improve the design of unconventional airships whose aerodynamics might be quite different from classical configurations. Once the airship geometry has been defined, testing is required to acquire aerodynamic data necessary to implement the mathematical model of the airship needed by the flight control system to develop full autonomous capabilities. Rapid prototyping has the great potential of playing a beneficial role in unconventional autonomous airship design similarly to the success obtained in the design process of conventional aircrafts. By reducing model cost, build time, difficulty of construction, and maintaining acceptable surface quality and finish, designers have greater ability to analyze several configurations of airships and to change the geometry in order to increase stability, reduce drag, or fulfill mission requirements.
Technical Paper
2013-09-17
Abdallah Ben Mosbah, Manuel Flores Salinas, Ruxandra Botez, Thien-my Dao
One of the hardest tasks involving wind tunnel characterization is to determine the air-flow condition inside the test section. The Log-Tchebycheff method and the Equal Area method allow calculation of local velocities from measured differential pressures on rectangular and circular ducts. However, these two standard methods for air flow measurement are limited by the number of accurate pressure readings by the Pitot tube. In this paper, a new approach is presented for wind tunnel calibrations. This approach is based on a limited number of dynamic pressure measurements and a predictive technique using Neural Network (NN). To optimize the NN, the extended great deluge (EGD) algorithm is used. Wind tunnel testing involves a large number of variables such as wind direction, velocity, rate flow, turbulence characteristics, temperature variation and pressure distribution on airfoils. NN has the advantage that multilayer perceptron neural networks can describe a 3D flow area with a small amount of experimental data, fewer numbers of iterations and less computation time per iteration.
Technical Paper
2013-09-08
Daniele Littera, Alessandro Cozzolini, Marc Besch, Mario Velardi, Daniel Carder, Mridul Gautam
Stringent emission regulations have forced drastic technological improvements in diesel after treatment systems, particularly in reducing Particulate Matter (PM) emissions. Those improvements generally regard the use of Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF) and lately also the use of Selective Catalyst Reduction (SCR) systems along with improved engine control strategies for reduction of NOx emissions from these engines. Studies that have led to these technological advancements were made in controlled laboratory environment and are not representative of real world emissions from these engines or vehicles. In addition, formation and evolution of PM from these engines are extremely sensitive to overall changes in the dilution process. In light of this, the study of the exhaust plume of a heavy duty diesel vehicle operated inside a subsonic environmental wind tunnel can give us an idea of the dilution process and the representative emissions of the real world scenario.
Standard
2013-07-09
The report shows how the methodology of measurement uncertainty can usefully be applied to test programs in order to optimize resources and save money. In doing so, it stresses the importance of integrating the generation of the Defined Measurement Process into more conventional project management techniques to create a Test Plan that allows accurate estimation of resources and trouble-free execution of the actual test. Finally, the report describes the need for post-test review and the importance of recycling lessons learned for the next project.
Standard
2013-06-05
This SAE Aerospace Recommended Practice (ARP) provides performance station designation and nomenclature systems for aircraft propulsion systems and their derivatives.
Standard
2013-05-16
This aerospace recommended practice (ARP) addresses the care, use, and training required to employ an effective borescope inspection program. Five subsections are included that cover training, storage, preoperational inspections, operation, and postoperational care related to both rigid and flexible borescopes. Throughout this ARP, proper borescope system nomenclature and terminology are utilized as specified in SAE ARP4022, Borescope Inspection System Definitions.
Technical Paper
2013-05-13
Richard Kolano
This paper presents the design, construction, and implementation of a novel sound transmission loss (STL) testing fixture that is unique to the automotive industry. This fixture was built within a large 1.68 m high × 2.74 wide (5′6″ × 9′0″) opening in the wall between a 497 m3 (17,591 ft3) reverberation room and an adjacent anechoic chamber. The fixture was designed and built to accommodate interchangeable plugs that allow STL measurements on an automotive ‘buck’ as well as on flat sample materials. It features a removable sample holding frame system that simply and quickly clamps in place and acoustically seals with a pneumatically inflated seal.
Technical Paper
2013-05-13
Richard Kolano, Sanjay Abhyankar, Thomas Martin
This paper presents the upgrades and improvements needed to bring an old and seldom used reverberation room test suite up to current standards. The upgrades and improvements included eliminating a below-floor pit that was open to the reverberation room, improving the acoustical diffusion within the room, enlarging the opening between the reverberation room and an adjacent anechoic chamber, renovating the anechoic receiving chamber, constructing an innovative sound transmission loss test fixture, and installing of a high power reverberation room sound system.
Technical Paper
2013-05-13
Claudio Bertolini, Tommy Falk
The use of small reverberation rooms for the measurement of the Diffuse Field Absorption Coefficient (DFAC) is common practice in the automotive industry. Such practice brings with itself a few issues, related to the limited size of the measurement environment. Some of these issues (e.g. measurements’ repeatability and reproducibility) have already been thoroughly investigated in articles published at past SAE NV Conferences. This paper intends to focus on some other “minor” aspects related to the measurement of DFAC in small reverberation rooms that so far have received little attention but that can, anyhow, have a non-negligible influence on the measurement results, in particular when they have to be compared to target curves. These “minor” aspects involve, for example, the use of metal frames to seal the edges of test samples, the effect of using correlated or un-correlated signals for the excitation loudspeakers, the importance of taking into account the environmental conditions (like temperature and humidity) and the effect of microphones’ size and orientation.
Technical Paper
2013-05-13
Filip Nauwelaerts, David Moens, Kristof Harri
When qualifying prototype samples in terms of vibration response and dynamic characteristics, an accredited laboratory is required to implement monitoring procedures to assure the validity of the test results. According to ISO17025, such monitoring may include inter-laboratory comparison or proficiency testing. This paper presents a mechanical structure which has been designed specifically to be used as a generic reference sample during such a comparative study in which resonant frequencies of a structure need to be quantified. This paper elaborates on the analysis and design issues, which encompass theoretical analysis, both purely mathematical and by FEM (Finite Element Modeling). In addition, to allow statistical analysis of test data resulting from measurements performed by different test laboratories, the uncertainty budget [1] of the reference value of this sample is determined. As a first step towards a European project, a limited group of accredited test laboratories in Belgium have participated in a first Round Robin proficiency analysis.
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