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This paper is the first of two papers that address the simulation and effects of turbulence on surface vehicle aerodynamics. This, the first paper, focuses on the characteristics of the turbulent flow field encountered by a road vehicle. The natural wind environment is usually unsteady but is almost universally replaced by a smooth flow in both wind tunnel and computational domains. In this paper, the characteristics of turbulence in the relative-velocity co-ordinate system of a moving ground vehicle are reviewed, drawing on work from Wind Engineering experience. Data are provided on typical turbulence levels, probability density functions and velocity spectra to which vehicles are exposed. The focus is on atmospheric turbulence, however the transient flow field from the wakes of other road vehicles and roadside objects are also considered.

The paper presents experimental analysis of the airflow around the differential center housing of a rear drive full-scale passenger car. The study included investigation of local airflow total and static pressure, as well as surface flow visualization. Estimation of the local airflow velocity is based on the measured pressure coefficients. The experiments were carried out at different test facilities: in a climatic wind tunnel, in a full-scale wind tunnel and on-road. Influence of side wind was modeled by the yawing of the car in the full-scale wind tunnel. The results show the asymmetrical structure of the flow in both, vertical and horizontal planes. Estimated longitudinal relative local velocity decreases from maximum Vr ≈ 0.4 at the lower surface of the center housing, to about Vr ≈ 0 above the upper surface. Side wind increases airflow velocity around the center housing within the investigated yaw range ± 20°

The design of a longitudinal stability augmentation system (SAS) for an aircraft with reduced tail size in the preliminary design phase is presented. Reducing tail size will reduce drag and weight and result in better fuel consumption, but it will reduce the level of stability. A control law is designed to give the aircraft the same stability level as that with the initial tail size. The feedback gains of the control law is computed with the equivalent stability derivative criteria of and CmαCmq . The paper also gives an overview of classical root locus and pole placement method and demonstrates that equivalent stability derivative criteria is suitable for preliminary aircraft design applications. Moreover, the control laws are also synthesized using robust control LQG/LTR which can be elaborated more in the detail design phase.

The focus of internal combustion (IC) engine research is the improvement of fuel economy and the reduction of the tailpipe emissions of CO2 and other regulated pollutants. Promising solutions to this challenge include the use of both direct-injection (DI) and alternative fuels such as liquefied petroleum gas (LPG). This study uses Mie-scattering and schlieren imaging to resolve the liquid and vapor phases of propane and iso-octane, which serve as surrogates for LPG and gasoline respectively. These fuels are imaged in a constant volume chamber at conditions that are relevant to both naturally aspirated and boosted, gasoline direct injection (GDI) engines. It is observed that propane and iso-octane have different spray behaviors across these conditions. Iso-octane is subject to conventional spray breakup and evaporation in nearly all cases, while propane is heavily flash-boiling throughout the GDI operating map.

High-frequency pressure probes were used to map the airflow around a full-scale truck during on-road testing and around a model-scale truck during wind tunnel testing. Several configurations were tested during each type of testing. Results are presented for on-road ‘pass-by’ tests and detail velocity and coefficient of pressure variation alongside the truck at different heights. The wind tunnel data are results of flow mapping about a 10% scale model and show the velocity and coefficient of pressure distribution under and around the model truck for different configurations.

This paper presents the conceptual design of a new low-cost measurement system for the determination of pollutant concentrations associated with aircraft operations. The proposed system employs Light Detection and Ranging (LIDAR) and passive electro-optics equipment installed in two non-collocated components. The source component consists of a tuneable small-size and low-cost/weight LIDAR emitter, which can be installed either on airborne or ground-based autonomous vehicles, or in fixed surface installations. The sensor component includes a target surface calibrated for reflectance and passive electro-optics equipment calibrated for radiance, both installed on an adjustable support. The proposed bistatic system determines the column-averaged molecular and aerosol pollutant concentrations along the LIDAR beam by measuring the cumulative absorption and scattering phenomena along the optical slant range.

One of the primary hazards associated with the operation of Unmanned Aircraft (UA) is the controlled or uncontrolled impact of the UA with terrain or objects on the terrain (e.g., people or structures). National Aviation Authorities (NAAs) have the responsibility of ensuring that the risks associated with this hazard are managed to an acceptable level. The NAA can mandate a range of technical (e.g., design standards) and operational (e.g., restrictions on flight) regulatory requirements. However, work to develop these regulations for UA is ongoing. Underpinning this rule-making process is a safety case showing how the regulatory requirements put in place ensure that the UA operation is acceptably safe for the given application and environment.

The air entrainment process of a compressed natural gas transient fuel jet was investigated in a constant-volume chamber using Schlieren and particle image velocimetry (PIV) techniques. A new method of calculating air entrainment around a gaseous fuel jet is proposed using Schlieren and PIV imaging techniques. This method offers an alternative to calculation of an alternative to calculation of entrainment using LIF technique in gaseous fuel jets. Several Jet-ambient pressure ratios were tested. In each test, nitrogen was used to fill the chamber as an air surrogate before the jet of natural gas was injected. Schlieren high speed videography and PIV experiments were performed at the same conditions. Schlieren mask images were used to accurately identify the jet boundary which was then superimposed onto a PIV image. Vectors adjacent to the Schlieren mask in the PIV image were used to calculate the spatial distribution of the air entrainment at the jet boundary.

Traditional User/Maintenance Manuals provide useful information when dealing with simple machines. However, when dealing with complex systems of systems and highly miniaturized technologies, like UAVs, or with machines with millions of parts, a commercial aircraft is a case in point, new technologies taking advantage of Augmented Reality can rapidly and effectively support the maintenance operations. This paper presents a User/Maintenance Manual based on Augmented Reality to help the operator in the detection of parts and in the sequence to be followed to assemble/disassemble systems and subsystems. The proposed system includes a handheld device and/or an head mounted display or special goggles, to be used by on-site operators, with software management providing data fusion and overlaying traditional 2D user/maintenance manual information with an augmented reality software and appropriate interface.

The maturity reached in the development of Unmanned Air Vehicles (UAVs) systems is making them more and more attractive for a vast number of civil missions. Clearly, the introduction of UAVs in the civil airspace requiring practical and effective regulation is one of the most critical issues being currently discussed. As several civil air authorities report in their regulations “Sense and Avoid” or “Detect and Avoid” capabilities are critical to the successful integration of UAV into the civil airspace. One possible approach to achieve this capability, specifically for operations beyond the Line-of-Sight, would be to equip air vehicles with a vision-based system using cameras to monitor the surrounding air space and to classify other air vehicles flying in close proximity. This paper presents an image-based application for the supervised classification of air vehicles.

Significant research has been made on traditional pre-mixed charge Spark-Ignition Natural-Gas engines which have seen widespread usage across the automotive sector. Many researchers including those in industry are now exploring the Direct-Injection concept for Natural-Gas Spark-Ignition engines. Direct-Injection has significant performance benefits over port-fuel injection, primarily due to increased volumetric efficiency as a result of injecting the fuel after intake valve closure. This could lead to enhanced driving performance over port-fuel injection comparable to gasoline engines. Furthermore, Direct-Injection with increased compression ratio in conjunction with downsizing concepts has the potential to increase thermal efficiency while exhibiting significantly lower CO2 emissions. Advanced combustion strategies like stratified mixture combustion has been widely studied for gasoline and proven to increase the low load thermal efficiency over homogeneous stoichiometric combustion.