User Defined Function: lidar_3D : NORSEWInD Report UoSNW006

This report describes the User Defined Function Lidar_3D used to interrogate FLUENT data files to provide the relevant data for the MathCAD LiDAR simulation program. The UDF was written in the C programming language and compiled using Microsoft visual studio 2008. This report contains a listing of the program (version 1.03). This report contains a description of the methodology required to compile the UDF so that it may be called by an "execute on demand" call from FLUENT. The report also includes a description of the input and output data file formats

Computational and Experimental Study on the effect of flow field distortion on the accuracy of the measurements made by anemometers on the Fino3 Meteorological mast

This paper reports on the experimental and computational modelling of the flow field around the FINO3 mast and provides an estimate of the amount of distortion that might be expected on instrumentation mounted on such a large structure. The open source C++ toolbox OpenFOAM was used for the CFD analysis. In order to validate the CFD model, experimental work was carried out in an open section wind tunnel using hot wire anemometry to measure the velocity profile around a sub-scale model of part of the FINO3 mast. The experimental data are in good agreement with the data from the CFD simulatio

Feasibility Study of using a LiDAR in the complex flowfield of an offshore platform, to measure wind shear profile.

Offshore wind is the major growth area in the wind industry sector today. However, there remains a key, fundamental missing element - a thorough understanding of the offshore wind climatology and likely wind resource. In 2008 the EU FP7 funded project NORSEWInD was created with a remit to deliver offshore wind speed data at a nominal project hub height acquired in offshore locations in the North, Baltic and Irish seas. Part of the overall NORSEWInD project was the use of LiDAR remote sensing (RS) systems mounted on offshore platforms to measure wind velocity profiles at a number of locations offshore. The data acquired from the offshore RS measurements was fed into a large and novel wind speed dataset suitable for use by the wind industry. The data was also fed into key areas such as forecasting and MESOSCALE modelling improvements. One significant problem identified was the effect of platform interference effects on the RS data. Therefore, part of the fundamental research incorporated into the NORSEWInD project was an investigation into the possible extent and effect of the interference on the measured data from the various mounting platforms. This paper reports on the Computational Fluid Dynamics (CFD) modelling of the wind flows over the platforms and the verification of the CFD models by the use of sub scale wind tunnel models employing three dimensional Constant Temperature Anemometers (CTAs) to measure local velocity vector data

Study of a regenerative pump using numerical and experimental techniques

Regenerative pumps are the subject of increased interest in industry as these pumps are low cost, low specific speed, compact and able to deliver high heads with stable performance characteristics. The complex flow-field within the pump represents a considerable challenge to detailed mathematical modelling as there is significant flow separation in the impeller blading. This paper presents the use of a commercial CFD code to simulate the flow within the regenerative pump and compare the CFD results with new experimental data. The CFD results demonstrate that it is possible to represent the helical flowfield for the pump which has only been witnessed in experimental flow visualisation until now. The CFD performance results also demonstrate reasonable agreement with the experimental tests. The CFD models are currently being used to optimise key geometric features to increase pump efficiency

Rapid manufacturing technique used in the development of a regenerative pump impeller

This paper presents a method of rapid manufacture used in the development of a regenerative pump impeller. Rapid manufacturing technology was used to create complex impeller blade profiles for testing as part of a regenerative pump optimisation process. Regenerative pumps are the subject of increased interest in industry. Ten modified impeller blade profiles, from the standard radial configuration, were evaluated with the use of computational fluid dynamics and experimental testing. Prototype impellers were needed for experimental validation of the CFD results. The manufacture of the complex blade profiles using conventional milling techniques is a considerable challenge for skilled machinists. The complexity of the modified blade profiles would normally necessitate the use of expensive CNC machining with 5 axis capability. With an impeller less than 75 mm in diameter and a maximum blade thickness of 1.3mm, a rapid manufacturing technique enabled production of complex blade profiles that were dimensionally accurate and structurally robust enough for testing. As more advanced rapid prototyping machines become available in the study in the future, e.g. 3D photopolymer jetting machine, the quality of the parts particularly in terms of surface finish will improve and the amount of post processing operations will reduce. This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture. The ability to manufacture complex blade profiles that are robust enough for testing, in a rapid and cost effective manner is proving essential in the overall design optimisation process for the pump

NORSEWInD Data Report and Correction Data for Berlengas : NORSEWInD Report UoSNW026

The flow field over Berlengas has been simulated on both a sub scale wind tunnel model in a low speed wind tunnel and in a computational fluid dynamics simulation. The CFD model has been validated by the results of the wind tunnel simulation. A simulation of measurements that would be made by a ZephIR LiDAR mounted on the island has been undertaken using the CFD results A method by which the distortion to the flow field over an offshore platform, measured by either a met mast or LiDAR, can be corrected back to the free stream value has been presented and verified. Correction factors have been calculated and are included in the appendix to this report. Based on the CFD and wind tunnel data it is was evident that significant flow distortion exists up to 425m above the island

Fluent User Defined Function: WindCube_comp_sim : NORSEWInD Report UOSNW013

This report describes the Fluent User Defined Function WindCube_comp_sim used to interrogate FLUENT a Fluent data set by simulating the operation of a LeoSphere Windcube LiDAR. The user defined function is contained in the program lidar.c (version 1.06) which has been written in the C programming language. This report contains a listing of the user defined function, describes its method of operation and presents a validation of the analysis process. The report also includes a description of the output data file formats

Comparison of Zephir and Windcube measurements in the same complex flowfield

Offshore wind is the major growth area in the wind industry sector today. However, there remains a key, fundamental missing element - a thorough understanding of the offshore wind climatology and likely wind resource. In 2008 the EU FP7 funded project NORSEWInD was created with a remit to deliver offshore wind speed data at a nominal project hub height acquired in offshore locations in the North, Baltic and Irish seas. Part of the NORSEWInD project is the use of LiDAR remote sensing (RS) systems mounted on offshore platforms to measure wind velocity profiles. The data acquired from the offshore RS measurements are fed into a large wind speed dataset suitable for use by the wind industry. One significant problem identified was the effect of platform interference effects on the RS data. Another significant effect on the quality of the data produced was the method by which the wind speed and direction was acquired as the method by which LiDARs measure the wind vector is significantly different from a point measurement. Whilst this will have no effect in a homogeneous flow field if there is significant flow distortion, which might be found in close proximity to a large structure or in complex terrain, then the effect of this spatially averaged measurement might cause a significant deviation from a point measurement. This paper reports on the modelling of two different types of LiDAR, the Natural Power ZephIR and the Leosphere Windcube, in a computational fluid dynamics simulation of the flow around a large offshore structure. The paper discusses the difference in the measured wind vector when compared to a point measurement at the measurement height

Particle image velocimetry studies of bubble growth and detachment by high speed photography

An understanding of bubble flows is important in the design of process equipment, particularly in the chemical and power industries. In vapour-liquid processes the mass and heat transfer between the phases is dominated by the liquid-vapour interface and is determined by the number, size and shape of the bubbles. For bubble flows these characteristics are often controlled by the generation mechanisms and, since bubble flows are often generated at an orifice, it is important to determine the controlling parameters which dictate how bubbles grow and detach. For bubbles growing at orifices the liquid displacement is an important feature and affects the pressure distribution acting on the bubble and the heat and mass transfer that may occur at the bubble interface. Therefore, in this study, the characteristics of the liquid velocity field are studied experimentally using Particle Image Velocimetry (PIV) during growth, detachment and translation of a bubble being generated at an orifice supplied with a constant mass flow rate of air. The process is transient and occurs over a period of approximately 50 msecs. In order to map the transient flow field a combination of high speed cine and cross correlation PIV image processing has been used to determine the liquid velocity vector field during the bubble growth process. The paper contains details of the PIV technique and presents several of the velocity vector maps calculated