Search results for "Aerospace Engineering"
showing 10 items of 378 documents
Vibrations of a continuous web on elastic supports
2017
We consider an infinite, homogenous linearly elastic beam resting on a system of linearly elastic supports, as an idealized model for a paper web in the middle of a cylinder-based dryer section. We obtain closed-form analytical expressions for the eigenfrequencies and the eigenmodes. The frequencies increase as the support rigidity is increased. Each frequency is bounded from above by the solution with absolutely rigid supports, and from below by the solution in the limit of vanishing support rigidity. Thus in a real system, the natural frequencies will be lower than predicted by commonly used models with rigid supports. peerReviewed
Racecar Longitudinal Control in Unknown and Highly-Varying Driving Conditions
2020
This paper focuses on racecar longitudinal control with highly-varying driving conditions. The main factors affecting the dynamic behavior of a vehicle, including aerodynamic forces, wheel rolling resistance, traction force resulting from changing tire-road interaction as well as the occurrence of sudden wind gusts or the presence of persistent winds, are considered and assumed to have unknown models. By exploiting the theory on delayed input-state observers and using measurement data about the vehicle and wheel speeds, a dynamic filter that allows the online reconstruction of the above-mentioned unknown time-varying quantities is derived. Moreover, by exploiting the notion of effective tir…
Take-off aerodynamics in ski jumping
2001
The effect of aerodynamic forces on the force-time characteristics of the simulated ski jumping take-off was examined in a wind tunnel. Vertical and horizontal ground reaction forces were recorded with a force plate installed under the wind tunnel floor. The jumpers performed take-offs in non-wind conditions and in various wind conditions (21-33 m s(-1)). EMGs of the important take-off muscles were recorded from one jumper. The dramatic decrease in take-off time found in all jumpers can be considered as the result of the influence of aerodynamic lift. The loss in impulse due to the shorter force production time with the same take-off force is compensated with the increase in lift force, res…
Experimental characterisation of the CIRA plasma wind tunnel SCIROCCO test section
2008
Abstract During the Validation Phase of the CIRA-PWT SCIROCCO Facility located at Capua (Italy), a test campaign has been carried out to verify the performances of the facility with the use of the two conical nozzle configurations “D” and “F” with exit diameters are, respectively of, 1150 and 1950 mm. For the first time the data results of the tests have been used to characterize the plasma flow in the test section of the facility. In particular, analytical relationships between the main thermo-fluid-dynamic parameters in the test section and the reservoir conditions of the facility have been found, and compared to the CFD prediction developed during the Design Phase of the facility. Very i…
A preliminary method for the numerical prediction of the behavior of air bubbles in the design of Air Cavity Ships
2016
Air-cavity ships (ACS) are advanced marine vehicles that use air injection under hull to improve the vessel’s hydrodynamic characteristics. Although the concept of drag reduction by supplying gas under the ship’s bottom was proposed in the 19th century by Froude and Laval, at this time there are not many systematic studies on this subject. This paper is a preliminary work with the purpose of being a basic tool for the design of the ACS with computational fluid dynamic methods. The study aims to conduct a series of computational tests to compare the numerical models of bubble with experimental data. The first step of this study was to investigate the behavior of free bubble in water, conside…
Experimental Determination of Liquefied Petroleum Gas–Gasoline Mixtures Knock Resistance
2014
The results of previous experimental researches showed that great advantages can be achieved, both in terms of fuel consumption and pollutant emissions, in bifuel vehicles by means of the double-fuel combustion, i.e., the simultaneous combustion of gasoline and a gaseous fuel, such as liquefied petroleum gas (LPG) or natural gas (NG). The substantial increase in knock resistance pursued by adding LPG to gasoline, which allowed to maintain an overall stoichiometric proportion with air also at full load, is not documented in the scientific literature and induced the authors to perform a proper experimental campaign. The motor octane number (MON) of LPG–gasoline mixtures has been hence determi…
A Novel Wideband MIMO Car-to-Car Channel Model Based on a Geometrical Semi-Circular Tunnel Scattering Model
2016
In this paper, we present a wideband multiple-input multiple-output (MIMO) car-to-car (C2C) channel model based on a geometrical semi-circular tunnel (SCT) scattering model. From the geometrical SCT scattering model, a reference channel model is derived under the assumption of single-bounce scattering in line-of-sight (LOS) and non-LOS (NLOS) propagation environments. In the proposed reference channel model, it is assumed that an infinite number of scatterers are randomly distributed on the tunnel wall. Starting from the geometrical scattering model, the time-variant transfer function (TVTF) is derived, and its correlation properties in time, frequency, and space are studied. Expressions ar…
DETERMINATION AND ANALYSIS OF HEAD AND CHEST PARAMETERS BY SIMULATION OF VEHICLE-TEENAGER IMPACT
2013
This paper reports the results of multi-body numerical simulation of a vehicle crash with a teenager pedestrian. A previous technique utilized for adult pedestrian impact is applied. The work starts with the determination of the masses for the various segments of the body of a teenager with a total mass of 45 kg and then switches to the construction of the dummy and the middle-class vehicle in the Visual Nastran environment. Simulations are performed for both frontal impacts and lateral impacts, when the vehicle is travelling at a constant speed and when the vehicle is braking, following the Euro NCAP rules on the subject. The results are analysed by calculating the values of the head inju…
PCM Thermal Energy Storage in Buildings: Experimental Study and Applications
2015
Abstract The study aims at analyzing the performance of Phase Change Materials (PCMs) in residential housing for different climates. This paper presents the results of an experiment performed in the Concordia University Solar Simulator and Environmental Chamber research facility (SSEC, Montreal, Canada). PCM boards were embedded on the back wall of a test hut placedin the climatic chamber. Several experiments were performed to explore the potential for verification of the proposed analysis and to produce enough data to perform model calibrations. Results show a strong increase in the apparent thermal inertia of the room allowing for a reduction in daily temperature fluctuations in the test …
Hardware-in-the-loop implementation for an active heave compensated drawworks
2012
Published version of an article published in the journal: Central European Journal of Engineering. Also available from the publisher at: http://dx.doi.org/10.2478/s13531-011-0062-1 This paper presents the setup and running of a hardware-in-loop (HIL) simulation for an active heave compensated (AHC) draw-works. A simulation model of the draw-works is executed on a PC to simulate the AHC draw-works with a physical PLC. The PLC (ET200S) is configured with a controller architecture that regulates the motor angular displacement and velocity through actuation of the servo valves. Furthermore, a graphical user interface is developed for operation of the AHC system. The HIL test allowed tuning of t…