Road accidents caused by heavy rain have become a frightening issue in recent years requiring investigation. In this regard, an aerodynamic comparative and experimental rain study is carried out to observe the flow phenomena change around a generic ground vehicle (Ahmed Body at a scale) and the utility truck. In this paper, a Discrete Phase Model (DPM) based computational methodology is used to estimate the effect of rain on aerodynamic performance. First, an experimental rain study of the Ahmed body at a scale that is representative of a car or light truck was conducted at the Wall of Wind (WOW) large-scale testing facility using force measurement equipment. In addition, the experiment allowed drag, lift, and side-force coefficients to be measured at yaw angles up to 55 degrees. Next, experimental results are presented for the Ahmed Body back angle of 35 degrees, then compared to validate the computational model for ground vehicle aerodynamics. Afterwards, we investigated the effect of heavy rainfall (LWC = 30 g/m3) on the external aerodynamics of the utility truck with the morphing boom equipment using the validated computational fluid dynamics method, and the external flow is presented using a computer visualization. Finally, force & moment coefficients and velocity distributions around the utility truck are computed for each case, and the results are compared. Keywords: Experimental Wind-Driven Rain Wind Tunnel Testing, Heavy Rainfall, The Ahmed Body, Utility Truck, Morphing Boom Equipment, Discrete Phase Model (DPM), Automotive Aerodynamics, Computational Fluid Dynamics (CFD)
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Aerodynamic Analysis of the Utility Truck With the Morphing Boom Equipment
Global climate change has affected the human race for decades. As a result, severe weather changes and more substantial hurricane impact have become a typical scenario. Utility trucks with the morphing boom equipment are the first responders to access these disaster areas in bad weather conditions and restore the damages caused by the disaster. The stability of the utility trucks while driving in a heavy wind scenario is an essential aspect for the safety of the rescue crew, and aerodynamic forces caused by the wind flow constitute a significant factor that influences the stability of the utility truck. In this paper, the aerodynamic performance of the utility truck is modeled using the incompressible unsteady Reynolds Averaged Navier Stokes (URANS) model. The Ahmed body, a well-recognized benchmark test case used by the computational fluid dynamics (CFD) community for the aerodynamic model validation of automobiles, is used to validate this aerodynamic model. The validated aerodynamic model investigates the impact of heavy wind on the utility truck with the morphing boom equipment. The visualization of the flow field around the utility truck with the force and moment coefficients at various side slip angles are presented in this paper.
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- Award ID(s):
- 1849264
- NSF-PAR ID:
- 10438560
- Date Published:
- Journal Name:
- Aerodynamic Analysis of the Utility Truck With the Morphing Boom Equipment
- Volume:
- 2
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Utility trucks are the first responders in extreme climate and severe weather situations, for saving people’s lives to restoring traffic on the roads. However, such trucks can create dangerous situations on the roads, and off-road conditions, while moving, and performing tasks. Trucks equipped with large booms for reaching elevated heights can become unstable due to their geometry change, which can cause a drastic variation of the truck-boom system’s moment of inertia, and the extreme weight re-distribution among the wheels. Morphing capabilities of the utility trucks need to be investigated together with the vehicle-road forces in order to hold the vehicle safe on the roads.
In this research paper, static analysis and range of the normal reaction at the wheel of the utility truck is performed to characterize a safe working zone of the boom equipment when the truck is in the flat and titled surface. The analysis is performed for 5-degree of freedom boom equipment with revolute and translational joints in a complex constrained space given by the truck design using 3D moment and force-vector analysis. The possible morphing configuration of the boom equipment is examined in order to define static normal reactions at the wheel-road interaction.
Further, the morphing of the boom equipment is investigated to determine limiting configurations that can be reached without rolling over the truck. In this analysis, it is assumed that the wheels provide enough friction between the tires and road so that tire slippage does not extensively occur, and the utility truck is assumed as a rigid body. In this study, utility truck equipped with boom equipment is utilized in this study for numerical illustration.
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Utility trucks with boom equipment function on environmentally sensitive areas and severe terrains where off-road conditions may cause significant damage to the trucks’ mobility and their safe operation. Indeed, considerable variations of landscape elevation and dynamic changes of terrain properties lead to extensive differences in the wheel normal reactions, drastic fluctuations of the rolling resistance at each tire, and finally, substantial changes in the total resistance to motion, which includes both the tire rolling resistance and the resistance due to the truck gravity component. Additionally, lateral forces caused by truck inclinations can lead to instability in motion, too. As a result, a utility truck can become immobilized in either longitudinal or lateral direction of movement because of one or the combination of the following events – loss of longitudinal mobility due to extensive tire slippage at some/all wheels, loss of lateral mobility due to tire side skid or rollover of the truck. To eliminate the above-listed causes that can lead to the utility truck immobilization, this study suggests a novel approach to managing the input/output factors that influence both longitudinal and lateral forces of the utility truck. In fact, the 3D morphing of the boom equipment is proposed as the input factor for managing the wheel normal reactions as the outputs. Ultimately, a changeable positioning of the boom equipment relative to the truck frame results in variable wheel normal reactions, which are the main contributors to the normal tire deformation and soil compaction, and thus, to the rolling resistance of each and all tires. This paper presents and discusses the method and results of computational simulations of the F450-based utility truck with boom equipment on medium mineral soil. The normal reaction at each wheel is evaluated under which the boom equipment morphs safely without causing roll over of the truck and, consequently, the total resistance to the motion force is determined. Modeling and simulation of the truck were conducted with the use of terramechanics-based tire-terrain models. This research study of the rolling resistance contributes to a research project on morphing utility truck, dynamics in severe terrain conditions. Keywords: Utility Truck, Morphing, Terrain Mobilitymore » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/FEDSM2022-88368
