Browsing by Author "Soares, Renan Francisco"
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Item Open Access On the aerodynamics of an enclosed-wheel racing car: an assessment and proposal of add-on devices for a fourth, high-performance configuration of the DrivAer model(SAE, 2018-04-30) Soares, Renan Francisco; Goñalons Olives, S. M.; Knowles, A. P.; Garry, Kevin P.; Holt, Jennifer C.A modern benchmark for passenger cars – DrivAer model – has provided significant contributions to aerodynamics-related topics in automotive engineering, where three categories of passenger cars have been successfully represented. However, a reference model for highperformance car configurations has not been considered appropriately yet. Technical knowledge in motorsport is also restricted due to competitiveness in performance, reputation and commercial gains. The consequence is a shortage of open-access material to be used as technical references for either motorsport community or academic research purposes. In this paper, a parametric assessment of race car aerodynamic devices are presented into four groups of studies. These are: (i) forebody strakes (dive planes), (ii) front bumper splitter, (iii) rear-end spoiler, and (iv) underbody diffuser. The simplified design of these add-ons focuses on the main parameters (such as length, position, or incidence), leading to easier manufacturing for experiments and implementation in computational studies. Consequently, a proposed model aims to address enclosed-wheel racing car categories, adapting a simplified, 35% scaled-model DrivAer Fastback shape (i.e. smooth underbody, no wheels, and with side mirrors). Experimental data were obtained at the 8ft x 6ft Cranfield Wind Tunnel using an internal balance for force and moment measurements. The aerodynamic performance of each group of add-on was assessed individually in a range of ride heights over a moving belt. All cases represent the vehicle at a zero-yaw condition, Reynolds number (car length-based) of 4.2 × 106 and Mach number equal to 0.12. The proposed high-performance configuration (DrivAer hp-F) was tested and a respective Reynolds number dependency study is also provided. In line with the open-access concept of the DrivAer model, the CAD geometry and experimental data will be made available online to the international community to support independent studies.Item Open Access Wake characterisation and simulation for ground vehicles(2020-04) Soares, Renan Francisco; Garry, Kevin P.This project aims to develop a generic, adaptable device able to emulate the distinct aerodynamic wake characteristics corresponding to different closed-wheel automotive vehicle categories, avoiding the use of a full-body vehicle model(s). The intention is to reduce complexity in both wind tunnel experimental testing and computational simulation, enhancing the capability of experimental facilities to study interference effects between vehicles in close proximity (e.g. platoon formation, drafting) and allowing faster build, meshing and computation time for CFD studies. The overall approach uses both computational and experimental investigationson generic automotive configurations (e.g. DrivAer models), particularly in relation to wake development and detailed flow structures. CFD simulations are mainly used for preliminary flow analysis and aerodynamic design, while the wind tunnel established the experimental, benchmark datasets. The three standard DrivAer vehicle configurations were adopted for studies relating to passenger cars, while the proposed 4th configuration (‘high-performance’) was developed and proposed as a benchmark model for race car aerodynamics. Two extensive, experimental wake datasets on the four DrivAer configurations have been created, the first using a pressure-based technique (total pressure rake), and the second applying an image-based method (Stereoscopic Particle Image Velocimetry). Additional experimental analyses support each wake dataset, such as (i) investigation of the effects of experimental conditions, (ii) Reynolds number characteristics and (iii) statistical analysis .These automotive wake benchmarks were used as the basis for the development of a conceptual wake generator, which is intended to be adaptable and able to ii generate representative wakes equivalent to automotive bodies. The development and key aerodynamic characteristics of this device are outlined, and each configuration experimentally validated using wind tunnel data. The complex wake structures associated with each of the four vehicle configurations are categorised, and the resulting wake emulator is seen to be capable of reproducing the key features within the wake development region of interest (i.e.0.666<𝑥/𝑊<1.33, where 𝑥/𝑊 is the distance behind the vehicle normalised by the DrivAer model width, 𝑊). This thesis is concluded with the proposal of a wake generator device as a new tool to support further development on automotive aerodynamics.