Aerodynamic Characteristics of a Road Vehicle in Steady-State Cornering

2015 ◽  
Author(s):  
Takuji Nakashima ◽  
Makoto Tsubokura ◽  
Yoshihiro Okada ◽  
Takahide Nouzawa ◽  
Ryosuke Kono ◽  
...  
Keyword(s):  
Steady State ◽  
Fluid Dynamic ◽  
Pressure Change ◽  
Aerodynamic Characteristics ◽  
Vehicle Body ◽  
Road Vehicle ◽  
Physical Mechanisms ◽  
Tank Experiment ◽  
Vehicle Motion ◽  
Towing Tank Experiment

The objective of this study was to investigate the aerodynamics of a road vehicle during cornering. We focused on steady-state cornering and divided the vehicle motion into two components, a yaw rotation and a sideslip motion. The fluid-dynamic characteristics of the vehicle in steady-state cornering and the effects of the two motion components were investigated both by a towing tank experiment and by numerical simulation. The results indicate that both of the motion components generated fluid-dynamic centripetal force and fluid-dynamic yaw moments in opposite directions. The distributions of pressure change on the vehicle body, generated by the motion components, were numerically visualized. The physical mechanisms that generated these aerodynamic characteristics are discussed.

scholarly journals Test Results of a Polymer Radiator of MTZ-80 Tractor Cooling System

2020 ◽  
Vol 14 (1) ◽  
pp. 55-60
Author(s):  
O. N. Didmanidze ◽  
R. T. Khakimov ◽  
E. P. Parlyuk ◽  
N. A. Bol’shakov
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Cooling System ◽  
Operating Mode ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
Hydrodynamic Resistance ◽  
Measuring Instruments ◽  
Research Areas ◽  
In Series

Global car manufacturers wish to increase the number of manufactured products, reduce their cost and labor input. The choice of research areas, design and technological developments in radiator construction is an extremely important and urgent task, due to the mass production of radiators for tractors and automobiles on the one hand, and the favorable development prospects of these interrelated industries, on the other. (Research purpose) To substantiate theoretically and experimentally the use of a combined cooling system containing both aluminum and polymeric water radiators and similarly liquid-oil heat exchangers based on the four principles listed above on automobiles and tractors. (Materials and methods) The authors performed bench tests using a special wind tunnel to study the thermal and aerodynamic characteristics of a prototype tractor radiator with a polyurethane core. After reaching the steady-state operating mode of the installation, the experimental values were determined for the control and measuring instruments. (Results and discussion) The authors carried out measurements of all parameters of both coolants in series at each steady-state operating mode of the bench. They obtained the main indicators dependences (reduced heat transfer, aerodynamic and hydraulic drag) of the heat exchanger, close to the operating conditions of the vehicles. (Conclusions) A prototype MTZ-80 radiator with a polyurethane core has great prospects as a future alternative radiator. An increase by 10-15 percent in the radiator heat transfer is possible by using aluminum fi ns on the surface of the polyurethane plate. A 15-20 percent reduction in hydrodynamic resistance is achieved by increasing the diameter of the capillary throughput in a polyurethane plate and the number of plates themselves in the radiator cell.

scholarly journals HELIUM RELEASE FROM 12Cr18Ni10Ti STAINLESS STEEL AFTER IMPACT OF STEADY STATE GLOW DISCHARGE He PLASMA

2021 ◽  
pp. 32-36
Author(s):  
G.P. Glazunov ◽  
M.N. Bondarenko ◽  
A.L. Konotopskiy ◽  
I.E. Garkusha ◽  
S.M. Maznichenko ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Steady State ◽  
Glow Discharge ◽  
Thermal Desorption ◽  
Gas Discharge ◽  
Plasma Pressure ◽  
Discharge Voltage ◽  
Probe Surface ◽  
Physical Mechanisms ◽  
He Atom

The thermal desorption experiments were carried out to study the process of helium outgassing from the stainless steel 12Cr18Ni10Ti after exposure to a steady state glow discharge (GD) plasma in He atmosphere. The currentvoltage characteristics in different plasma regimes have been measured and estimation of He ions energy has been made. Measurements of He release from the stainless steel probes showed the saturation of probe surface with He after the fluencies of ~ 4 ∙ 1019 ion/cm2. The value of He outgassing strongly depends on the regime of GD plasma: pressure of work gas, discharge voltage, etc. Several maximums, including the maximum at the temperature of 100…150 °C, were registered in the He desorption curves that indicated different He atom states on the surface and in the nearest surface bulk. Physical mechanisms of such He outgassing are discussed.

Model Predictive Controller Design for Vehicle Motion Control at Handling Limits in Multiple Equilibria on Varying Road Surfaces

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6667
Author(s):  
Szilárd Czibere ◽  
Ádám Domina ◽  
Ádám Bárdos ◽  
Zsolt Szalay
Keyword(s):  
Steady State ◽  
Vehicle Dynamics ◽  
Multiple Equilibria ◽  
Stability Control ◽  
Equilibrium Analysis ◽  
Stable Region ◽  
Test Scenario ◽  
Sideslip Angle ◽  
Road Surfaces ◽  
Vehicle Motion

Electronic vehicle dynamics systems are expected to evolve in the future as more and more automobile manufacturers mark fully automated vehicles as their main path of development. State-of-the-art electronic stability control programs aim to limit the vehicle motion within the stable region of the vehicle dynamics, thereby preventing drifting. On the contrary, in this paper, the authors suggest its use as an optimal cornering technique in emergency situations and on certain road conditions. Achieving the automated initiation and stabilization of vehicle drift motion (also known as powerslide) on varying road surfaces means a high level of controllability over the vehicle. This article proposes a novel approach to realize automated vehicle drifting in multiple operation points on different road surfaces. A three-state nonlinear vehicle and tire model was selected for control-oriented purposes. Model predictive control (MPC) was chosen with an online updating strategy to initiate and maintain the drift even in changing conditions. Parameter identification was conducted on a test vehicle. Equilibrium analysis was a key tool to identify steady-state drift states, and successive linearization was used as an updating strategy. The authors show that the proposed controller is capable of initiating and maintaining steady-state drifting. In the first test scenario, the reaching of a single drifting equilibrium point with −27.5° sideslip angle and 10 m/s longitudinal speed is presented, which resulted in −20° roadwheel angle. In the second demonstration, the setpoints were altered across three different operating points with sideslip angles ranging from −27.5° to −35°. In the third test case, a wet to dry road transition is presented with 0.8 and 0.95 road grip values, respectively.

Hot-spot reaction under transient pressure conditions

1987 ◽  
Vol 413 (1845) ◽  
pp. 329-350 ◽  
Keyword(s):  
Hot Spots ◽  
Hot Spot ◽  
Thermodynamic Description ◽  
Exothermic Reaction ◽  
Pressure Change ◽  
Variable Pressure ◽  
Transient Pressure ◽  
Physical Mechanisms ◽  
Solid Explosives ◽  
Condensed Phase Explosives

The initiation of condensed-phase explosives is often caused by hot spots; that is, localized regions of high temperature created by a variety of physical mechanisms, particularly in solid explosives. Once the hot spots are created, further temperature change is governed by (i) self-heating due to chemical reaction, (ii) heat loss by conduction and radiation, and (iii) adiabatic effects due to pressure and specific volume variation. The last effect includes both self-induced pressure change due to thermal expansion against the surroundings, and externally generated pressure change when initiation is attempted by mechanical impact. This paper presents a thermodynamic description of exothermic reaction under conditions of variable pressure and volume. The reaction rate is assumed to be a function of temperature only. The effect of variable pressure enters through its influence on temperature. It is demonstrated that the effects of self-induced pressure change are small. In the case of externally generated pressure change, explosion times can be affected drastically. These results are discussed in terms of initiation by shock waves of finite duration.

The Modeling of Electrohydraulic Proportional Valves

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Davide Cristofori ◽  
Andrea Vacca
Keyword(s):  
Steady State ◽  
Linear Model ◽  
Nonlinear Model ◽  
3D Model ◽  
Fluid Dynamic ◽  
Body Motion ◽  
General Nature ◽  
Relief Valve ◽  
Real Component ◽  
Electromagnetic Model

The present work describes the modeling of a proportional relief valve actuated by an electromagnet. Two models were developed and compared each other: a detailed nonlinear model and its linearized version. The modeling approach presented has a general nature and can be applied to various types of electrohydraulic proportional valves (EHPV). The comparison between nonlinear and linear model results shows the limits of the linear approximation to study the real component. Substantially, the nonlinear model is composed by three submodels: the fluid-dynamic model (for the evaluation of the main flow features), the mechanical model (which solves the mobile body motion), and the electromagnetic model (which evaluates the magnetic forces and the electric transient). All submodels are based on a lumped parameter (LP) approach and they implement a specific set of nonlinear equations. However, to carefully model the main electromagnetic phenomena that characterize the proportional electromagnet behavior (including: magnetic losses, fringing effects, and magnetic saturation), a finite element analysis (FEA) 3D model was developed by the authors. The LP electromagnetic model is based on a particular use of the FEA 3D model steady state results. A series of transient simulations were performed through the FEA 3D model in order to quantify the effect of the eddy currents and to determine a second order transfer function used in the linear model to describe the electromagnet dynamics. The remaining parts of the linear model are obtained by linearizing the nonlinear model equations. The FEA 3D model was experimentally validated in steady-state conditions, while the results of the overall model of the valve were verified in both steady-state and dynamic conditions.

Studies on Aerodynamic Characteristics of Dump Diffusers for Modern Aircraft Engines

2012 ◽  
Vol 232 ◽  
pp. 246-251 ◽  
Author(s):  
P. Sathyan ◽  
S. Srikanth ◽  
I. Dheepan ◽  
M. Arun ◽  
C. Aswin ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Finite Volume Scheme ◽  
Aircraft Engines ◽  
Navier Stokes Equations ◽  
Dynamic Constraints ◽  
Fully Implicit

The geometrical optimization of dump diffusers are extremely demanding as the flow fields and stress fields are very complex and must be well understood to achieve the required design efficiencies. In this paper parametric analytical studies have been carried out for examining the aerodynamics characteristics of different dump diffusers for modern aircraft engines. Numerical studies have been carried out using SST K- ω turbulence model. This code solves SST k- ω turbulence equations using the coupled second order implicit unsteady formulation. In the numerical study, a fully implicit finite volume scheme of the compressible, Reynolds-Averaged, Navier-Stokes equations is employed. We concluded that in addition to the dump gap ratio, the aerodynamic shape of the flame tube case and the other geometric variables are also need to be optimized judiciously after considering the fluid dynamic constraints for controlling the pressure recovery and the losses.

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