A Statistical Analysis of Surface Pressure Measurements with Particular Reference to Vortex Breakdown. G.U. Aero Report 9806

This paper describes and presents results from static wind tunnel tests conducted on a 60° delta wing at a root chord Reynolds number of 2.7 x 10[sup]6. In these tests, the wing was instrumented with 192 miniature pressure transducers which, in conjunction with a powerful multi-channel data-logging system, allowed the distribution of timevarying surface pressures to be measured at high temporal resolution. Analysis indicates that the distribution of root-mean-square pressure on the leeward surface of the wing can provide considerable insight into the behaviour of both the primary and secondary vortex structures. In addition, it has been established that the frequency content of pressure signals measured in the vicinity of these vortex structures is sensitive to the vortex state. It is suggested that these data features can be directly attributed to previously observed behavioural characteristics of the vortex breakdown process

Wind Tunnel Investigations into the Air Flow around the Existing and Proposed Bridges at Kingston. G.U. Aero Report 9316

This report presents the results obtained from a series of flow visualisation and flow measurement wind tunnel tests, carried out at Glasgow University, on models of the existing and proposed Kingston bridges. The background to the tests, commissioned by Strathclyde Regional Council after discussions with staff from the Department of Aerospace Engineering, is provided in the Introduction. Details of the facilities employed and bridge representation are included also. The important experimental consideration of Similarity is addressed in some detail, with particular reference to the use of appropriate scaling parameters for flow frequencies and velocities in the vicinity of the bridges. Test results are presented firstly in the form of still photographs of the illuminated smoke traces, with the main features illustrated by the provision of flow diagrams for each test. Secondly, the more quantitative measurements are presented as graphs of velocity versus time at a variety of measuring stations. In addition, selected video records have been made and are available on an accompanying, indexed VHS cassette. A detailed discussion of the results is presented, and five main conclusions are made concerning the structure of the flow around the existing and proposed bridges

A Preliminary Study of the Flow around a Delta Wing using High Resolution Pressure Measurements. G. U. Aero Report no. 9720

A study of the flow around delta wings has been carried out in a series of experiments in the University’s Handley-Page Wind-Tunnel facility. The objective of the experiments was to capture high spatial and temporal resolution pressure measurements on a specially designed 60° delta wing model. This project has been devised to analyse the results of the study with a view to determining a reliable method of vortex breakdown detection on delta wings using data obtained from pressure measurements alone. A fundamental requirement of the proposed method is that it should apply equally under static and dynamic conditions. In order to achieve the aim of the project, a broad understanding of the physics of vortical flows is required. This is to be achieved in two ways; firstly, by carrying out a literature research exercise on the nature, causes and effects of vortex breakdown, secondly, to validate the findings of the pressure data analysis by carrying out further experiments using smoke visualisation techniques. The findings of the literature research exercise are presented, together with a description of the wind-tunnel experiments and the preliminary results from the analysis of the pressure data. The models to be used in the forthcoming smoke visualisation experiments have been built and a series of tests have been carried out to evaluate their design. A description of the smoke tunnel models and the results of these tests are also presented. The work of this project has so far highlighted a number of issues to be dealt with in future research as part of this project. To conclude this report, a series of proposals are presented detailing the work required to resolve these issues

The Development of a Prescribed Wake Model for the Prediction of the Aerodynamic Performance of Horizontal Axis Wind Turbines in Steady Axial Flow. Departmental report no. 9403

Summary: The development of phase one of a new model for the prediction of the aerodynamic performance of horizontal axis wind turbines is described in the following report. At present the model is configured for performance prediction under steady axial flow conditions. Geometry prescription techniques, based on conservation of momentum, are employed to determine the shape of the turbine wake. This wake is modelled as a series of vortex filaments which, via the Biot-Savart relationship, allows the loadings on the turbine to be evaluated. As is the case with free wake models, a closed form solution is excluded due to the nature of the problem and iterative procedures are, therefore, used to obtain a good prediction. As well as a detailed description of the model, it’s structure and the numerical procedures employed are described. The results obtained from the scheme are satisfactory at this stage of development but further validation is required. The work described in this report is intended to act as the basis for the development of a more comprehensive prescribed wake model, which should yield results of similar accuracy to firee wake calculations while requiring only a fraction of the computational effor

A Prescribed Wake Model for Horizontal Axis Wind Turbine Incorporating Yaw and Dynamic Inflow. G.U. Aero Report 9543

The following report summarises a three year research programme in the Department of Aerospace Engineering, University of Glasgow to develop a comprehensive prescribed wake aerodynamic model for horizontal axis wind turbines (HAWTs) capable of considering yawed and yawing flow. The original motivation for the work lay in the extensive and successful use of similar methodologies for vertical axis wind turbines and in the helicopter field. It was considered that the developed scheme would be suitable for design applications; running in minutes rather than hours. The approach used was similar to that of Coton et al.(1994) for vertical axis wind turbine applications where the blade was represented as a lifting line and a lattice of shed and trailing vortex filaments comprised the wake. The spatial and temporal development of the wake was pre-assigned using prescription functions developed in the current study and the induced flow at the blades was calculated by application of the Biot-Savart equation. Initially, the model was validated against free wake and field data for steady axial flow but was then extended to consider yawed flow. As a final stage, the unsteady aerofoil performance scheme of Lieshman and Beddoes (1989) was incorporated to account for the dynamic changes in blade loading around the azimuth in yawed flow. The resulting model has been compared to wind tunnel test data and field data supplied by NREL from the combined experiment. The work has resulted in a comprehensive aerodynamic model which is currently the focus of a follow-on EPSRC study (GR/K14995) which will extend its capabilities further

Analysis of model rotor blade pressures during parallel interaction with twin vortices

This paper presents and provides analysis of unsteady surface pressures measured on a model rotor blade as the blade experienced near parallel blade vortex interaction with a twin vortex system. To provide a basis for analysis, the vortex system was characterized by hot-wire measurements made in the interaction plane but in the absence of the rotor. The unsteady pressure response resulting from a single vortex interaction is then presented to provide a frame of reference for the twin vortex results. A series of twin vortex interaction cases are then presented and analyzed. It is shown that the unsteady blade pressures and forces are very sensitive to the inclination angle and separation distance of the vortex pair. When the vortex cores lie almost parallel to the blade chord, the interaction is characterized by a two-stage response associated with the sequential passage of the two cores. Conversely, when the cores lie on a plane that is almost perpendicular to the blade chord, the response is similar to that of a single vortex interaction. In all cases, the normal force response is consistent with the distribution of vertical velocity in the flow field of the vortex system. The pitching moment response, on the other hand, depends on the localized suction associated with the vortex cores as they traverse the blade chord

Control of rotorcraft retreating blade stall using air-jet vortex generators

A series of low-speed wind tunnel tests were carried out on an oscillating airfoil fitted with two rows of air-jet vortex generators (AJVGs). The airfoil used had an RAE 9645 section and the two spanwise arrays of AJVGs were located at x/c=0.12 and 0.62. The devices and their distribution were chosen to assess their ability to modify/control dynamic stall; the goal being to enhance the aerodynamic performance of helicopter rotors on the retreating blade side of the disc. The model was pitched about the quarter chord with a reduced frequency (k) of 0.1 in a sinusoidal motion defined by a=15o+10sin_ t. The measured data indicate that, for continuous blowing from the front row of AJVGs with a momentum blowing coefficient (C μ) greater than 0.008, modifications to the stalling process are encouraging. In particular, the pitching moment behavior exhibits delayed stall and there is a marked reduction in the normal force hysteresis

Cell fueling and metabolic energy conservation in synthetic cells

We aim for a blue print for synthesizing complex subcellular systems from molecular components and ultimately for constructing life. Without comprehensive instructions and design principles we rely on simple reaction routes to operate the essential functions of life. The first forms of synthetic life will not make every building block for polymers de novo via complex pathways, rather they will be fed with amino acids, fatty acids and nucleotides. Controlled energy supply is crucial for any synthetic cell, no matter how complex. Here, we describe the simplest pathways for efficient generation of ATP and electrochemical ion gradients. We estimated the demand for ATP by polymer synthesis and maintenance processes in small cell-like systems, and we describe circuits to control the needs for ATP. We also present fluorescence-based sensors for pH, ionic strength, excluded volume, ATP/ADP, and viscosity, which allow monitoring and tuning of the major physicochemical conditions inside cells