Academic literature on the topic 'Tire and Road Wear Particles (TRWP)'

Research and/or Engineering Question/Objective: The fine dust contribution (<10µm) of motor vehicles represents a considerable health risk for people in urban areas. Due to an increasing percentage of electric vehicles, exhaust emissions are steadily reduced. Consequently, particles from non-exhaust sources (brake, tire and road ware) are considered to be the future main vehicle related pollutant. While regenerative braking, tungsten carbide coatings and filter devices can effectively reduce brake wear emissions, there is currently no methodology available in order to reduce tire wear particles, road abrasion and resuspension. In addition, the tire is one of the main sources of environmental microplastic pollution. Although there are initial approaches to determine the emission characteristics of tire and road ware particles, there is a lack of basic understanding of the underlying physical processes. Methodology: The particle flow around the vehicle wheelhouse is dominated by highly dynamic vortex structures. The numerical flow simulation (CFD) is a well suited tool for the investigation of these processes and allows a detailed analysis of the particle-flow interaction. Within this paper, a CFD flow model of a vehicle wheelhouse is presented, which analytically describes the underlying physical effects of particle dispersion by the vehicle tire. The CFD model was applied in order to define a suitable measurement strategy for the measurement of TRW particles based on a measurement vehicle. Results: In order to develop a CFD Modell for tire-induced particle emissions, comprehensive analysis of mesh generation, geometric influencing factors and turbulence models was conducted. An essential element of the presented model is the modelling of the wheel rotation, tire-road contact and tire-profile related effects. In addition, particle models were adapted according to the physical properties of tire and road wear particles. In a second step, the CFD methodology was applied in order to design a constant volume sampling system (CVS) which ensures a maximum sampling and transport efficiency for TRW particles. Limitations of this study: In general, numerical simulation requires strong simplification of the physical problem and can cover aspects of the flow and particle behavior only partially. Thus, more experiments are necessary to fully validate the CFD model. What does the paper offer that is new in the field in comparison to other works of the author: The paper offers a new CFD-based tire and road wear model including flow processes in proximity to the tire-road interface, in order to describe tire induced particle emissions. Conclusion: Within this paper a novel CFD-based methodology is presented whereby special emphasis was placed towards the modelling of tire-induced particle emissions. This model was applied in order to design a constant volume sampling system that ensures a maximum sampling as well as transport efficiency for TRW particle measurement. KEYWORDS - Tire and Road Wear Particles (TRW), Particle Resuspension, Non-Exhaust-Emissions, Computational Fluid Dynamics (CFD), Constant Volume Sampling System (CVS)

<div class="section abstract"><div class="htmlview paragraph">Dust testing of vehicles on unpaved roads is crucial in the development process for automotive manufacturers. These tests aim to ensure the functionality of locking systems in dusty conditions, minimize dust concentration inside the vehicle, and enhance customer comfort by preventing dust accumulation on the car body. Additionally, deposition on safety-critical parts, such as windshields and sensors, can pose threats to driver vision and autonomous driving capabilities. Currently, dust tests are primarily conducted experimentally at proving grounds. In order to gain early insights and reduce the need for costly physical tests, numerical simulations are becoming a promising alternative.</div><div class="htmlview paragraph">Although simulations of vehicle contamination by dry dust have been studied in the past, they have often lacked detailed models for tire dust resuspension. In addition, few publications address the specifics of dust deposition on vehicles, especially in areas such as door gaps and locks. Many authors focus primarily on the environmental impact of vehicles due to non-exhaust emissions, such as tire and road wear particles (TRWP) and brake wear on paved roads.</div><div class="htmlview paragraph">To close this gap, this paper presents an experimental test in which a vehicle drives through a dry dust track. Using special dust measurement techniques positioned in the wheelhouse, we determine the number and size distribution of the dust particle field around the tire circumference. The results of this experiment provide a deeper understanding of the dust dispersion patterns generated by tires on unpaved surfaces and serve as valuable data for boundary conditions and for the validation of CFD (computational fluid dynamics) simulations.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Dry dust testing of vehicles on unpaved dust roads plays a crucial role in the development process of automotive manufacturers. One of the central aspects of the test procedure is ensuring the functionality of locking systems in the case of dust ingress and keeping the dust below a certain concentration level inside the vehicle. Another aspect is the customer comfort because of dust deposited on the surface of the car body. This also poses a safety risk to customers when the dust settles on safety-critical parts such as windshields and obstructs the driver’s view. Dust deposition on sensors is also safety critical and is becoming more important because of the increasing amount of sensors for autonomous driving. Nowadays, dust tests are conducted experimentally at dust proving grounds. To gain early insights and avoid costly physical testing, numerical simulations are considered a promising approach.</div><div class="htmlview paragraph">Simulations of vehicle contamination by dry dust have been studied in the past. However, they lack detailed tire resuspension models, and none of the publications focus on the dust deposition at the vehicle in detail, such as door gaps and locks. Moreover, the emphasis of many authors is the environmental impact of vehicles resulting from non-exhaust emissions, such as tire and road wear, brake wear, and dust emissions.</div><div class="htmlview paragraph">This paper introduces a novel method for simulating the production of dust resulting from vehicles driving on a dry and dusty, unpaved road, as well as the subsequent deposition mechanisms that occur within door gaps and locks. To achieve this, both a basic, generic vehicle model and a more complex, detailed model of a Volkswagen (VW) Caddy are used in the context of a multiphase computational fluid dynamics (CFD) simulation with Lagrangian particles.</div></div>

The increasing degree of electrification as well as the optimization of particle based exhaust emissions, which is already being driven forward due to legislation, will direct the focus of fine dust considerations in automotive technology to non-exhaust emissions. In contrast to exhaust emissions, there are currently only a few vehicle-related limit values or uniform standards in measurement technology and the measurement procedure. The area of non-exhaust emissions includes tire abrasion, the turbulence of organic and inorganic road particles, and brake wear. Since, in addition to the material component, the particle size also has a significant influence on the health hazard of the material, particulate emissions from brakes are often directly related to health effects. In comparison to previous measurements, which have mostly been carried out in enclosed and clinical environments, the dynamics of the fine dust emitted from the brake will be investigated using a fully automated tribometer and used as a possibility to validate a DEM simulation. Besides the pure measurement of the emitted particle size distributions during the brake application, conclusions on the agglomeration behaviour of the emission particles in the environment shall be drawn. The aim is to predict the environmental impact and the potential danger of the particles to humans due to the particle size released into the environment. The pin-disc contact between brake pad and brake disc serves as the emission source. A coupled CFD-DEM simulation environment was set up to simulate particle dynamics. Based on a rotating brake disc model, the flow-relevant components of the test bench environment were implemented into the simulation setup. The area around the actual brake contact as well as the environment at the tribometer should be considered. For the metrological validation of the simulation, a swarm of calibrated low-cost sensors as well as a scattered light based particle size measuring device will be set up around the tribometer

"Since fine dust particles in the ambient air emitted by cars, trucks and busses are identified as a health risk, emissions from combustion engines are limited by law. The increasing change from combustion to electric power train as well as the use of gasoline and diesel particulate filters lead to a focus shift to other fine dust sources like tire or brake wear. To further reduce the fine dust pollution caused by road transportation, it is planned to limit particle emissions of brake systems of passenger vehicles by law. The PMP informal working group of the UNECE is already working on a measuring cycle and a suitable test method for this purpose for several years. Hence, a draft of a test protocol was published in June 2021 and is validated in a inter-laboratory study (ILS) at different labs The proposal describes a method to test a single brake-vehicle-combination. The analysis of the market in this regard reveals an extremely large number of possible pairings. Combined with the proposed duration of a complete test-run, this leads to a very high demand of testing to determine the variety of brake emissions of existing vehicle fleets in different markets. Hence, it is crucial to understand whether there are physical correlations between different test combinations to estimate the emission levels of brake-vehicle-pairings. The aim of this study is to investigate the influence of different vehicle and brake parameters in regard of the measured particle number and mass emission. In addition, the results are analysed for physically relevant correlations. This is done using various test series in which only individual test parameters, such as the size of the brake disc or the vehicle weight, are varied. The study also tries to address the effect of different measures for noise, vibration and harshness (NVH) of the brake system on the particle number and mass emission results. The results show that plausible predictions of the emission are possible for the variation of specific test parameters. On the other hand, there are test parameters that require additional information or even a separate emission test when they are changed. Since fine dust particles in the ambient air emitted by cars, trucks and busses are identified as a health risk, emissions from combustion engines are limited by law. The increasing change from combustion to electric power train as well as the use of gasoline and diesel particulate filters lead to a focus shift to other fine dust sources like tire or brake wear. To further reduce the fine dust pollution caused by road transportation, it is planned to limit particle emissions of brake systems of passenger vehicles by law. The PMP informal working group of the UNECE is already working on a measuring cycle and a suitable test method for this purpose for several years. Hence, a draft of a test protocol was published in June 2021 and is validated in a inter-laboratory study (ILS) at different labs The proposal describes a method to test a single brake-vehicle-combination. The analysis of the market in this regard reveals an extremely large number of possible pairings. Combined with the proposed duration of a complete test-run, this leads to a very high demand of testing to determine the variety of brake emissions of existing vehicle fleets in different markets. Hence, it is crucial to understand whether there are physical correlations between different test combinations to estimate the emission levels of brake-vehicle-pairings. The aim of this study is to investigate the influence of different vehicle and brake parameters in regard of the measured particle number and mass emission. In addition, the results are analysed for physically relevant correlations. This is done using various test series in which only individual test parameters, such as the size of the brake disc or the vehicle weight, are varied. The study also tries to address the effect of different measures for noise, vibration and harshness (NVH) of the brake system on the particle number and mass emission results. The results show that plausible predictions of the emission are possible for the variation of specific test parameters. On the other hand, there are test parameters that require additional information or even a separate emission test when they are changed. "