A study of the effects of the properties of fuel, compression ratio and EGR on diesel exhaust soot physiochemical characteristics

This research work characterises diesel engine soot physiochemical properties and engine performance and emissions for the combustion of two common mineral diesel fuels (low and medium sulphur) and a RME B100 biodiesel fuel at two geometric compression ratios (19.5:1 and 16.5:1) and a broad range of EGR (10 to 55%) for an otherwise unmodified VW 1.9TDI 130PS engine. The principal focus of the research is the physiochemical characterisation of soot sampled from the engine exhaust manifold and also a DPF in the exhaust and exploring how the fuel type, compression ratio and EGR influence the soot properties and how these properties then influence the evolution of the soot in the exhaust. [Continues.

A decision support methodology for process in the loop optimisation

Experimental optimisation with hardware-in-the-loop is a common procedure in engineering, particularly in cases where accurate modelling is not possible. A common methodology to support experimental search is to use one of the many gradient descent methods. However, even sophisticated and proven methodologies such as Simulated Annealing (SA) can be significantly challenged in the presence of significant noise. This paper introduces a decision support methodology based upon Response Surfaces (RS), which supplements experimental management based on variable neighbourhood search, and is shown to be highly effective in directing experiments in the presence of significant signal to noise (S-N) ratio and complex combinatorial functions. The methodology is developed on a 3-dimensional surface with multiple local-minima and large basin of attraction, and high S-N ratio. Finally, the method is applied to a real-life automotive experimental application

Experimental investigation of the acoustic black hole effect for flexural waves in tapered plates

An efficient method of reducing edge reflections of flexural waves in plates or bars based on the 'acoustic black hole effect' has been recently proposed and described theoretically by one of the present authors (V.V.K). The method utilises a gradual change in thickness of a plate or bar, partly covered by thin damping layers, from the value corresponding to the thickness of the basic plate or bar (which is to be damped) to almost zero. The present paper describes the results of the experimental investigation of the damping system consisting of a steel plate of quadratic shape (wedge) covered on one side by a strip of absorbing layer. The results of the measurements of point mobility in such a system show that for a wedge covered by an absorbing layer there is a significant reduction of resonant peaks, in comparison with the uncovered wedge or with the covered plate of constant thickness. Thus, the measurements confirm the existence of the acoustic black hole effect for flexural waves and demonstrate the possibility of its use in practice

Experimental evidence of the acoustic black hole effect for flexural waves in tapered plates

A new efficient method of reducing edge reflections of flexural waves in plates or bars based on the 'acoustic black hole effect' has been recently proposed and described theoretically by one of the present authors [1] (see also [2-4]). The method utilises a gradual change in thickness of a plate or bar, partly covered by thin damping layers, from the value corresponding to the thickness of the basic plate or bar (which is to be damped) to almost zero. The present paper describes the results of the experimental investigation of the damping system consisting of a steel plate (wedge) of quadratic shape covered on one side by a strip of absorbing layer. The results of the measurements of point mobility in such a system show that for the wedge covered by an absorbing layer there is a significant reduction of resonant peaks, in comparison with the uncovered wedge or with the covered plate of constant thickness. Thus, the measurements confirm the existence of the acoustic black hole effect for flexural waves and demonstrate the possibility of its use in practice

Modelling of vehicle interior noise at reduced scale

The present paper describes some recent results on the development of simplified reduced-scale models that can be used for experimental studies of vehicle interior noise. In many important cases such simplified structural models can be described analytically, thus providing a developer with the effective engineering tools for prediction and mitigation of vehicle interior noise, especially on a design stage. The general approach is illustrated by a 1:4-scale simplified model of a car developed at Loughborough University – 'QUASICAR' (QUArter –Scale Interior Cavity Acoustic Rig). The model consists of a curved steel plate that is simply supported by two rigid side walls made of massive wooden panels. The effect of road irregularities exciting vehicle structural vibrations is imitated by electromagnetic shakers applied to the bottom of the steel plate. Measurements of structural vibrations and of the acoustic pressure generated inside the model are compared with the results of theoretical predictions

Investigation of structural-acoustic coupling in a thin-walled reduced-scale model of a car

The present paper describes the results of the recent research into simplified reduced-scale thin-walled models that can be used for experimental studies of vehicle interior noise. In many important cases such models can be described analytically, thus providing a developer with the effective engineering tools for prediction and mitigation of vehicle interior noise, especially on a design stage. The structural simplification in the models is based on understanding the physics of generation of predominant modes of structural vibrations by particular dynamic forces and of radiation of sound by the excited vibrations into the vehicle interior. The above-mentioned general approach is illustrated by a 1:4-scale simplified physical model of a car developed at Loughborough University – 'QUASICAR' (QUArter –Scale Interior Cavity Acoustic Rig). The model consists of a curved steel plate that is simply supported by two rigid sidewalls made of massive wooden panels. The effect of road irregularities exciting vehicle structural vibrations is imitated by electromagnetic shakers applied to the bottom of the steel plate. Measurements of structural vibrations and of the acoustic pressure generated inside the model at different positions demonstrate their good conceptual agreement with the results of theoretical predictions

Simplified modelling of vehicle interior noise: comparison of analytical, numerical and experimental approaches

The present paper describes the results of the investigation of low and medium frequency vehicle interior noise carried out using simplified structural-acoustic models. Analytical, finite element (FE) and experimental studies are presented and compared. In particular, the analytical approach is based on the formula representing the interior acoustic pressure in terms of structural and acoustic normal modes. This procedure does not take into account the effect of the enclosed air on structural vibrations. The FE analysis considers structural vibration modes, interior acoustic modes, full structural-acoustic interaction and the resulting structure-borne noise. The above-mentioned analytical and numerical results are compared with each other, and both of them are compared with the experimental results obtained for the simplified reduced-scale vehicle model “QUASICAR” developed in Loughborough University. The comparisons demonstrate some specific features of the analytical and numerical approaches and outline the acceptable limits of simplification in modelling vehicle interior noise. Although this study is concerned with structure-borne vehicle interior noise, its results and conclusions could be of interest for a wider range of engineering problems, such as building acoustics and dynamics of thin shell structures

Finite element calculations of structural-acoustic modes of vehicle interior for simplified models of motorcars

The present paper describes the results of finite element analysis of structural vibration modes, interior acoustic modes, and structural-acoustic modes in some simplified models of road vehicles having different levels of complexity, in particular in the QUArter-Scale Interior Cavity Acoustic Rig (QUASICAR) developed in Loughborough University. All the analysis has been carried out using the original code that had been developed in Patran Command Language (PCL) specifically for the purpose of this research. Resonant frequencies and spatial distributions of structural and acoustic modes have been calculated initially separately and then taking into account structuralacoustic interaction. The results have been compared with the experimental data obtained for QUASICAR. The comparison has demonstrated good agreement between numerical calculations and experimental results. The developed approach is reliable and efficient, and it can be extended to more complex vehicle models, thus assisting in better understanding of vehicle interior noise

Three-input-three-output air path control system of a heavy-duty diesel engine

In this paper, the control requirement of the air path system of a Heavy Duty (HD) diesel engine which was equipped with a High Pressure (HP) Exhaust Gas Recirculation (EGR), a Variable-Geometry Turbocharger (VGT), and an Electric Turbocharge Assist (ETA) is discussed. A Three-Input-Three-Output (3130) multivariable control structure is proposed. The engine dynamic model required for controller design was obtained using system identification and the controller was tuned by solving an Hoo optimization problem. The engine experimental test results show that this 3130 closed-loop control system has excellent tracking performance, disturbance rejection performance, and gain scheduling capability. The control system has been demonstrated to work with a practical ETA device to make a substantial improvement to engine transient performance

Real-time energy management for diesel heavy duty hybrid electric vehicles

In this paper, a fuzzy-tuned equivalent consumption minimization strategy (F-ECMS) is proposed as an intelligent real-time energy management solution for a conceptual diesel engine-equipped heavy duty hybrid electric vehicle (HEV). In the HEV, two electric motors/generators are mounted on the turbocharger shaft and engine shaft, respectively, which can improve fuel efficiency by capturing and storing energy from both regenerative braking and otherwise wasted engine exhaust gas. The heavy duty HEV frequently involved in duty cycles characterized by start-stop events, especially in off-road applications, whose dynamics is analyzed in this paper. The on-line optimization problem is formulated as minimizing a cost function in terms of weighted fuel power and electric power. In the cost function, a cost factor is defined for both improving energy transmission efficiency and maintaining the battery energy balance. To deal with the nonexplicit relationship between HEV fuel economy, battery state of charge (SOC), and control variables, the cost factor is fuzzy tuned using expert knowledge and experience. In relation to the fuel economy, the air-fuel ratio is an important factor. An online search for capable optimal variable geometry turbocharger (VGT) vane opening and exhaust gas recirculation (EGR) valve opening is also necessary. Considering the exhaust emissions regulation in diesel engine control, the boundary values of VGT and EGR actuators are identified by offline design-of-experiment tests. An online rolling method is used to implement the multivariable optimization. The proposed method is validated via simulation under two transient driving cycles, with the fuel economy benefits of 4.43% and 6.44% over the nonhybrid mode, respectively. Compared with the telemetry equivalent consumption minimization strategy, the proposed F-ECMS shows better performance in the sustainability of battery SOC under driving conditions with the rapid dynamics often associated with off-road applications