A local area computer network expert system framework

Over the past years an expert system called LANES designed to detect and isolate faults in the Goddard-wide Hybrid Local Area Computer Network (LACN) was developed. As a result, the need for developing a more generic LACN fault isolation expert system has become apparent. An object oriented approach was explored to create a set of generic classes, objects, rules, and methods that would be necessary to meet this need. The object classes provide a convenient mechanism for separating high level information from low level network specific information. This approach yeilds a framework which can be applied to different network configurations and be easily expanded to meet new needs

Aerodynamic Analysis of Grand Prix Cars Operating in Wake Flows

The effect of the upstream wake of a Formula 1 car on a following vehicle has been investigated using experimental and computational methods. Multiple vehicle studies in conventional length wind tunnels pose challenges in achieving a realistic vehicle separation and the use of a short axial length wake generator provides an advantage here. Aerodynamic downforce and drag were seen to reduce, with greater force reductions experienced at shorter axial spacings. With lateral offsets, downforce recovers at a greater rate than drag, returning to the level for a vehicle in isolation for offsets greater than half a car width.The effect of the wake was investigated in CFD using multiple vehicle simulations and non-uniform inlet boundary conditions to recreate the wake. Results closely matched those for a full two-vehicle simulation provided the inlet condition included unsteady components of the onset wake. Creating a nonuniform inlet condition allowed the wake parameters to be modified to test sensitivity to different wake features. Dynamic pressure deficit in the wake is shown to have the greatest impact on the following vehicle, reducing loading on the downforce producing surfaces. Wake up-wash and vortex flows are shown to have a smaller effect on downforce generated by the following car, but have an important role in diverting the dynamic pressure deficit upwards and over the following car.Future regulation changes, aimed at reducing the downforce loss experienced when following another car, should aim to reduce the velocity deficit onset to the following car; either by reducing wheel and underbody wakes, or by extracting the wake using up-wash from the rear wing

CFD Investigation of the Effect of the Salient Flow Features in the Wake of a Generic Open-Wheel Race Car

It is well known that in motorsport the wake from an upstream vehicle can be detrimental to the handling characteristics of a following vehicle, in particular in formulae with high levels of downforce. Previous investigations have been performed to characterize the wake from an open wheel race car and its effect on a following car, either through the use of multiple vehicles or purpose-built wake generators.This study investigates how the wake of an upstream race car impacts the aerodynamic performance of a following car in a close-following scenario. Wakes are imposed on the inlet of a CFD simulation and wake parameters (eg: velocity deficit, trailing vorticity) are directly manipulated to investigate their individual impacts on the following vehicle.The approach provides a useful alternative to the simulation of multi-vehicle cases but a better simulation could be achieved by including wake unsteadiness from the upstream vehicle. Arguably the most significant impact of a wake on the following vehicle was found to be the rearward movement of the vehicle center of pressure. Secondary flow (eg: upwash, vorticity) on a bulk scale had the beneficial impact of moving the wake up and over the following vehicle but more localized impacts could be positive or negative according to the detailed interaction with downstream vehicle features

Automotive aerodynamics special edition

Automotive aerodynamics special editio

Wake and surface pressure analysis of vehicles in platoon

In this paper, the drag reduction benefits associated with 2 and 3 cars in platoon have been investigated. Following a validation of initial CFD simulations against experimental measurements, predictions of surface pressures and wake structure for alternative platoon configurations have been analysed to determine the changes of flow structure that influence the pressure field and drag force on each vehicle. Contrary to several publications it was found that in a platoon of two vehicles, the drag force of the trailing vehicle exceeded that of an isolated vehicle for close spacings. Analysis of this surprising result revealed that design features introduced to optimise the wake of an isolated vehicle can lead to a drag increase on a following vehicle. For three-vehicle platoons, the flow interaction between the leading and middle vehicles remained largely unchanged but the additional effect of the third vehicle resulted in all three vehicles exhibiting lower drag than that of an isolated vehicle. A clear implication of this work is that results from the analysis of vehicle platoons are likely to be sensitive to the geometry and wake structures of the chosen test vehicle which helps to explain why many previous studies have been seemingly contradictory

A novel method of strain - bending moment calibration for blade testing

A new method of interpreting strain data in full scale static and fatigue tests has been implemented as part of the Offshore Renewable Energy Catapult's ongoing development of biaxial fatigue testing of wind turbine blades. During bi-axial fatigue tests, it is necessary to be able to distinguish strains arising from the flapwise motion of the blade from strains arising from the edgewise motion. The method exploits the beam-like structure of blades and is derived using the equations of beam theory. It offers several advantages over the current state of the art method of calibrating strain gauges

Aerodynamics of electric cars in platoon SAGE publications

The potential aerodynamic benefits of operating full-scale electric vehicles in platoons of 2 and 3 vehicles have been investigated. Since drag reduction has a direct impact on vehicle range, power consumption was measured directly and surface pressure measurements were made to characterise the changes in pressure field that influence the power required to overcome aerodynamic drag. CFD simulations were validated against the track measurements to assess the limitations of using a practical, limited number of pressure tappings to measure drag. The overall power consumption for the whole platoon was found to reduce proportionally with the reduction of vehicle spacing and it was also observed that increasing the number of vehicles in the platoon from 2 to 3 further increased the power savings from 33.4% to 39.1%. These power savings were attributed primarily to changes in surface pressure acting on the base of the leading vehicle and the forebody of the trailing vehicle

Evaluation of vehicle platooning aerodynamics using bluff body wake generators and CFD

Recent developments in sensing and communications between vehicles (V2V) and their surroundings have provided the technology to allow cars to operate autonomously or semi-autonomously in closely spaced `platoon' formation without the risk of collision. This is known to reduce the aerodynamic drag and thus consequently limits the energy consumption and associated emissions. Although wind tunnel investigations have been performed to mimic platoon operations, most experimental evaluations of multiple vehicles in platoon are severely compromised by the restricted length of the wind tunnel test section. Therefore, the model scale must be reduced which decreases the measurement accuracy. The innovative solution presented here is to reproduce the flow structure that is created by a leading road car through the use of a `bluff-body wake generator' with a much reduced length which eliminates the need to decrease the scale of the following test model. Validated computational fluid dynamics (CFD) data and analysis are presented to evaluate an optimized design of a wake generator based on the Ahmed model [1] and the effect of inter-vehicle spacing on the aerodynamic characteristics of the following vehicle. It is shown that accurate reproduction of the wake is possible at half the characteristic length, thus correctly determining the flow impact on the downstream model. This demonstrates that the bluff body wake generator provides a reliable approach that allows platooning studies to be performed without sacrificing aerodynamic resolution