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In a rectangular cross-section wind tunnel a separated oblique shock reflection is set to interact with the turbulent boundary layer (oblique SBLI) both on the bottom wall and in the corner formed by the intersection of the floor with the side-walls. In such a scenario, shock-induced separation is often seen in each of the streamwise corners, resulting in a highly three-dimensional flow field in the near-wall region. To examine how the corner separations can affect the `quasi-two-dimensional' main interaction and by what mechanism this is achieved, an experimental investigation has been conducted. This examines how modifications to the corner separation influence an oblique shock reflection. The nature of the flow field is studied using flow visualisation, Pressure Sensitive Paint and Laser Doppler Anemometry. A nominal freestream Mach number of 2.5 is used for all experiments with a unit Reynolds number of $40\times10^6$m$^{-1}$, and the shock-generator angle is set to $8^\circ$. The flow conditions are chosen to result in substantial separations both in the corners and along the centreline for the baseline case, which is thought to be a good starting point for this study. The results show that the size and shape of central separation vary considerably when the onset and magnitude of corner separation change. The primary mechanism coupling these separated regions appears to be the generation of compression waves and expansion fans as a result of the displacement effect of the corner separation. The presence and strength of the expansion waves have been overlooked in previous studies. This is shown to modify the three-dimensional shock-structure and alter the adverse pressure gradient experienced by the tunnel floor boundary layer. It is suggested that a typical oblique SBLI in rectangular channels features several zones depending on the relative position of the corner waves and the main interaction domain. In particular, it has been shown that the position of the corner `shock' crossing point, found by approximating the corner compression waves by a straight line, is a critical factor determining the main separation size and shape. Thus, corner effects can substantially modify the central separation. This can cause significant growth or contraction of the separation length measured along the symmetry line from the nominally two-dimensional baseline value, giving a fivefold increase from the smallest to the largest observed value. Moreover, the shape and flow topology of the centreline separation bubble is also considerably changed by varying corner effects.

Side friction factors are defined as all those actions related to the activities taking place by the sides of the road and sometimes within the road, which interfere with the traffic flow on the travelled way. They include but not limited to pedestrians, bicycles, non-motorised vehicles, parked and stopping vehicles. These factors are normally very frequent in densely populated areas in developing countries, while they are random and sparse in developed countries making it of less interest for research and consequently there is comparatively little literature about them. The objective of this thesis is to analyze the effect of these factors on traffic performance measures on urban roads. To carry out this work, a research design was formulated including specific methods and prescribed limitations. An empirical case study methodology was adopted where Dar-es-salaam city in Tanzania was chosen as a representative case. The scope was limited to include only road-link facilities. A sample of these facilities including two-lane two-way and four-lane two-way roads were selected and studied. The study was conducted in two parts, of which each involved a distinctive approach. Part one involved a macroscopic approach where traffic and friction data were collected and analyzed at an aggregated level, whereas part two involved a microscopic approach where data of individual frictional elements were collected and analysed individually. Data collection was mainly performed by application of video method, which proved to be effective for simultaneous collection of traffic and side friction data. Data reduction was conducted chiefly by computer, using standard spreadsheet and statistical software packages, mainly SPSS and some computer macros. The analysis part was based on statistical methods, chiefly regression analysis. In the macroscopic approach, traffic and friction data from all sites were adjusted through a process called ‘normalization’, which enabled the data from the different sites to be merged, and consequently to obtain speed-flow curves for each road type. The individual friction factors through regression analysis were weighted and combined into one unit of measure of friction called "FRIC". The effect of "FRIC" on speed-flow curves was analyzed. The results showed significant impact on speed for both road types. Impact on capacity was identified on two-lane two-way roads while field data on four-lane two-way roads did not allow this. In the microanalysis approach, effect of individual side friction factors on speed was analyzed. The results showed that on two-lane two-way roads, all studied factors exhibited statistically significant impact on speed, while on four-lane two-way roads, only one factor showed the same. The results also identified impact values characteristic to the individual friction factors on some roads. Recommendations were made based on these results that highway capacity studies particularly in developing countries, should include the friction variable, though in the form suitable to their own particular circumstances. Further recommendations were made that these results should be applied to formulate management programs seeking to limit levels of side friction on high mobility urban arterial streets in order to improve traffic safety and operation efficiency. / <p>QC 20100701</p>

Neste trabalho, calibra-se um modelo que descreva a relação fluxo-velocidade em autoestradas e rodovias de pista dupla, considerando as recomendações tecidas pelos autores envolvidos na elaboração do modelo do Highway Capacity Manual - HCM 2010. Para tanto, foi utilizada uma amostra de 788.122 observações, coletadas por 25 estações em quatro rodovias paulistas: SP-348, SP-021, SP-280 e SP 270. A análise dos dados mostrou que, conforme preconizado pelo HCM 2010, existe um intervalo de fluxos no qual a velocidade se mantém constante, o que corresponde à velocidade de fluxo livre. Em seguida, verificou-se que a classificação do HCM 2010, entre autoestradas e rodovias de pista dupla, não se mostra adequada para a amostra estudada, tendo sido indicada a divisão entre rodovias urbanas e rurais. Para esses grupos, foram propostos valores representativos para a capacidade e calibrada a relação fluxo-velocidade. A comparação entre os dois conjuntos de curvas produzidos mostrou que a velocidade média da corrente de tráfego nas rodovias urbanas apresenta uma queda mais precoce e acentuada do que a observada em rodovias rurais. Além disso, os valores estimados para a capacidade C e para a velocidade na capacidade CS para rodovias urbanas são inferiores aos estimados para rodovias rurais. Em contraste com o modelo do HCM 2010, a principal diferença reside em valores significativamente inferiores para BP, o fluxo a partir do qual se nota um declínio da velocidade em função do aumento da densidade da corrente de tráfego. Outro ponto de destaque é que, embora os valores da capacidade sejam parecidos entre o modelo do HCM 2010 e o calibrado, a velocidade na capacidade CS é superior nas rodovias paulistas. / This work presents the calibration of a model describing the speed-flow relationship on freeways and multilane highways in the state of São Paulo, Brazil. The calibrated model follows the recommendations made by the authors involved in the development of the model used by the Highway Capacity Manual HCM 2010. The calibration used a sample of 788,122 observations, collected by 25 stations on four highways at São Paulo state: SP-348, SP-021, SP-280 and 270 SP. The analysis of the data showed that, as advocated by the HCM 2010, there is range of flows in which the average speed of the passenger cars remains constant and equal to the free flow speed. It was also found that the classification scheme used by HCM 2010, comprising freeways and multilane highways, is not adequate for highways in the state of São Paulo. A new classification scheme, which divides highways into urban or rural sections, is proposed. For these classes, representative values for the capacity were found, and the speed-flow relation was calibrated. The comparison between the two sets of curves produced showed that the average speed of the traffic stream on urban highways has an earlier and steeper drop than the observed on rural highways. In addition, the estimated values for the capacity C and for the speed at capacity CS for urban highways are lower compared to the estimated for rural highways. Compared to the model used by the HCM 2010, the main difference lies in the significantly lower values for BP, the traffic flow from which the average speed declines as the density of the traffic stream increases. Another important indication is that, although the capacity values are similar between the model used by the HCM 2010 and the calibrated model, the speed at capacity CS is higher at São Paulo state highways.

The issues of global warming and climate change are a worldwide concern and the UK government has committed itself to major reductions in CO2 emissions, the most significant of the six greenhouse gases. Road transport currently accounts for about 22% of total UK emissions of CO2, and has been steadily rising. Therefore, initiatives are required to try and reduce the gas emissions in this sector. The aim of this research has been to develop a computer based vehicle routing model that calculates the overall amount of CO2 emitted from road journeys, as well as time and distance. The model has been used to examine a number of delivery strategies to assess how CO2 emissions vary. The aim has not been to produce new mathematical theories, but to produce an innovative basis for routing which will provide new information and knowledge about how CO2 emissions vary for different minimisation and congestion criteria. The approach used in this research brings together elements from transportation planning and environmental modelling combined with logistics based vehicle routing techniques. The model uses a digitised road network containing predicted traffic volumes, to which speed flow formulae are applied so that a good representation of speed can be generated on each of the roads. This means that the model is uniquely able to address the issue of congestion in the context of freight vehicle routing. It uses driving cycle data to apply variability to the generated speeds to reflect acceleration and deceleration so that fuel consumption, and therefore CO2, can be estimated. Integrated within the model are vehicle routing heuristics to enable routes to be produced which minimise the specified criterion of time, distance or CO2. The results produced by the model show that there is a potential to reduce CO2 emissions by about 5%. However, when other transport externalities are considered overall benefits are dependent on road traffic volumes.

The issues of global warming and climate change are a worldwide concern and the UK government has committed itself to major reductions in CO2 emissions, the most significant of the six greenhouse gases. Road transport currently accounts for about 22% of total UK emissions of CO2, and has been steadily rising. Therefore, initiatives are required to try and reduce the gas emissions in this sector. The aim of this research has been to develop a computer based vehicle routing model that calculates the overall amount of CO2 emitted from road journeys, as well as time and distance. The model has been used to examine a number of delivery strategies to assess how CO2 emissions vary. The aim has not been to produce new mathematical theories, but to produce an innovative basis for routing which will provide new information and knowledge about how CO2 emissions vary for different minimisation and congestion criteria. The approach used in this research brings together elements from transportation planning and environmental modelling combined with logistics based vehicle routing techniques. The model uses a digitised road network containing predicted traffic volumes, to which speed flow formulae are applied so that a good representation of speed can be generated on each of the roads. This means that the model is uniquely able to address the issue of congestion in the context of freight vehicle routing. It uses driving cycle data to apply variability to the generated speeds to reflect acceleration and deceleration so that fuel consumption, and therefore CO2, can be estimated. Integrated within the model are vehicle routing heuristics to enable routes to be produced which minimise the specified criterion of time, distance or CO2. The results produced by the model show that there is a potential to reduce CO2 emissions by about 5%. However, when other transport externalities are considered overall benefits are dependent on road traffic volumes.

Neste trabalho, calibra-se um modelo que descreva a relação fluxo-velocidade em autoestradas e rodovias de pista dupla, considerando as recomendações tecidas pelos autores envolvidos na elaboração do modelo do Highway Capacity Manual - HCM 2010. Para tanto, foi utilizada uma amostra de 788.122 observações, coletadas por 25 estações em quatro rodovias paulistas: SP-348, SP-021, SP-280 e SP 270. A análise dos dados mostrou que, conforme preconizado pelo HCM 2010, existe um intervalo de fluxos no qual a velocidade se mantém constante, o que corresponde à velocidade de fluxo livre. Em seguida, verificou-se que a classificação do HCM 2010, entre autoestradas e rodovias de pista dupla, não se mostra adequada para a amostra estudada, tendo sido indicada a divisão entre rodovias urbanas e rurais. Para esses grupos, foram propostos valores representativos para a capacidade e calibrada a relação fluxo-velocidade. A comparação entre os dois conjuntos de curvas produzidos mostrou que a velocidade média da corrente de tráfego nas rodovias urbanas apresenta uma queda mais precoce e acentuada do que a observada em rodovias rurais. Além disso, os valores estimados para a capacidade C e para a velocidade na capacidade CS para rodovias urbanas são inferiores aos estimados para rodovias rurais. Em contraste com o modelo do HCM 2010, a principal diferença reside em valores significativamente inferiores para BP, o fluxo a partir do qual se nota um declínio da velocidade em função do aumento da densidade da corrente de tráfego. Outro ponto de destaque é que, embora os valores da capacidade sejam parecidos entre o modelo do HCM 2010 e o calibrado, a velocidade na capacidade CS é superior nas rodovias paulistas. / This work presents the calibration of a model describing the speed-flow relationship on freeways and multilane highways in the state of São Paulo, Brazil. The calibrated model follows the recommendations made by the authors involved in the development of the model used by the Highway Capacity Manual HCM 2010. The calibration used a sample of 788,122 observations, collected by 25 stations on four highways at São Paulo state: SP-348, SP-021, SP-280 and 270 SP. The analysis of the data showed that, as advocated by the HCM 2010, there is range of flows in which the average speed of the passenger cars remains constant and equal to the free flow speed. It was also found that the classification scheme used by HCM 2010, comprising freeways and multilane highways, is not adequate for highways in the state of São Paulo. A new classification scheme, which divides highways into urban or rural sections, is proposed. For these classes, representative values for the capacity were found, and the speed-flow relation was calibrated. The comparison between the two sets of curves produced showed that the average speed of the traffic stream on urban highways has an earlier and steeper drop than the observed on rural highways. In addition, the estimated values for the capacity C and for the speed at capacity CS for urban highways are lower compared to the estimated for rural highways. Compared to the model used by the HCM 2010, the main difference lies in the significantly lower values for BP, the traffic flow from which the average speed declines as the density of the traffic stream increases. Another important indication is that, although the capacity values are similar between the model used by the HCM 2010 and the calibrated model, the speed at capacity CS is higher at São Paulo state highways.

<div>The ambient pressure fluctuations within a wind tunnel test environment can severely affect the boundary layer transition witnessed on test articles The Boeing/AFOSR Mach 6 Quiet Tunnel was designed to minimize these fluctuations, also referred to as noise, and is the world's premier facility for studying hypersonic boundary layer transition in a quiet flow environment. All experiments performed for this work were conducted at this facility.</div><div><br></div><div> </div><div> The freestream flow field of this tunnel has been characterized multiple times since its creation, however an extensive three-dimensional spatial sweep has never been conducted. A pitot rake model was designed to allow for an extensive spatial survey of tunnel noise. This model created measurement capabilities that were previously unknown to the BAM6QT facility, including the ability to take concurrent freestream pitot probe measurements. The performance of this new measurement method was evaluated, and suggestions for future verification tests are made. The pitot rake appears to suffer from probe-probe interactions in certain configurations, and has demonstrated variation in measurements that depends on the individual sensor used.</div><div><br></div><div> </div><div> This new measurement apparatus was used to investigate the effect that cavities in the tunnel wall created by the installation of new optical windows had on the freestream noise level. A control dataset corresponding to a perfectly conformal tunnel wall was not collected during this work. The experiments conducted provide evidence that the tunnel wall cavities do increase the noise downstream of their location by approximately 100%, however a control dataset is needed to verify this finding.</div><div><br></div><div> </div><div> In addition to tunnel characterization, a novel flat plate model was evaluated for use in the BAM6QT. This model was intended for use as a platform for observing second mode instability growth. These experiments show that the initial flat plate geometry proved incompatible with the BAM6QT as the tunnel could not achieve nominal flow conditions with the model installed. The flat plate model was streamlined to rectify the startup issue, but no evidence of the second mode instability was found. A 2.5° half angle cone is being designed to replace the flat plate model as a platform for the continuation of this project.</div>

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