Highlights of unsteady pressure tests on a 14 percent supercritical airfoil at high Reynolds number, transonic condition

Steady and unsteady pressures were measured on a 2-D supercritical airfoil in the Langley Research Center 0.3-m Transonic Cryogenic Tunnel at Reynolds numbers from 6 x 1,000,000 to 35 x 1,000,000. The airfoil was oscillated in pitch at amplitudes from plus or minus .25 degrees to plus or minus 1.0 degrees at frequencies from 5 Hz to 60 Hz. The special requirements of testing an unsteady pressure model in a pressurized cryogenic tunnel are discussed. Selected steady measured data are presented and are compared with GRUMFOIL calculations at Reynolds number of 6 x 1,000,000 and 30 x 1,000,000. Experimental unsteady results at Reynolds numbers of 6 x 1,000,000 and 30 x 1,000,000 are examined for Reynolds number effects. Measured unsteady results at two mean angles of attack at a Reynolds number of 30 x 1,000,000 are also examined

On the estimation of foundation damping of mono pile-supported offshore wind turbines

This paper investigates the estimation of foundation damping in a monopile supported offshore wind turbine. The soil-structure interaction is modelled using the commercial geotechnical Finite Element (FE) software, Plaxis 3D. This allows for a more rigorous consideration of the soil response and its effect on the overall dynamic behaviour of the system. A free vibration test is simulated by applying and removing a constant horizontal static load at the top of the tower. The structure starts free vibration when the load is removed. The free decay displacement response is measured at the point of loading. The well-known logarithmic decrement method is used for the estimation of overall damping from the free decay response. The damping is estimated at different time steps along the signal to provide an instantaneous damping. It is shown that the damping varies with the amplitude of the decaying displacement response

Combustion, Fuels and Emissions for Industrial Gas Turbines

TutorialTutorial 5: It is important that gas turbines used in Oil & Gas applications can burn a wide variety of fuels with the minimum impact on the environment or economics. Many types of gaseous and liquid fuels that can be used in Gas Turbines are discussed, as will be the two basic types of combustion system employed – ‘conventional’ and ‘Dry Low Emissions’ – along with the flexibility of these systems to accept different types of fuel. Some of the common contaminants found in fuels are discussed along with the impact these have on the operability and maintenance of industrial and aero-derivative gas turbines. Topics include: Types of gas turbines, Types of exhaust emissions regulated, Conventional combustion systems, Dry Low (Pre-mixed) emissions combustion systems, Fuel quality requirements, ‘Pipeline’ quality Natural Gas fuels, Premium liquid fuels (diesel, kerosene), Wellhead Gases as a Gas Turbine Fuel, Liquified Natural Gas (LNG), Biogas fuels - Refinery and process off gases, Syngas, Natural Gas Liquids and LPG fuels, Crude Oil, Operational impact of contaminants, Water in fuel, Storing fuels correctly

Towards a Theory of Local Governance and Public Goods Provision

Under?provision of essential public goods is making development in Africa slower and more inequitable than it needs to be. A good part of this problem concerns the governance of provision at sub?national levels. This article provides a mid?term report on a multi?country research effort to shed light on the institutional sources of variation in local public goods provision. The particular focus is on key bottlenecks to improvement in maternal mortality, water and sanitation, facilitation of markets and enterprise, and public order and security. Drawing on fieldwork evidence and secondary literature, it identifies three clusters of issues and associated explanatory variables which seem to account for much of the variation in intermediate outcomes. They concern the extent of policy?driven incoherence in the institutional framework, the strength of corporate disciplines in provider organisations and the degree to which self?help is able to be ‘locally anchored’ in two particular senses

Protected areas and poverty

Protected areas are controversial because they are so important for conservation and because they distribute fortune and misfortune unevenly. The nature of that distribution, as well as the terrain of protected areas themselves, have been vigorously contested. In particular, the relationship between protected areas and poverty is a long-running debate in academic and policy circles. We review the origins of this debate and chart its key moments. We then outline the continuing flashpoints and ways in which further evaluation studies could improve the evidence base for policy-making and conservation practice

Piles for offshore wind turbines: A state of the art review

The paper considers the current state of the art for estimating the pull-out capacity of driven open-ended piles used to support wind turbine foundations founded on sand. The latest edition of the American Petroleum Institute guidelines for pile design includes a conventional earth pressure approach and four alternative cone penetration test (CPT) methods for estimating pile shaft resistance in sand. A database of open-ended pile tests was used to assess the predictive reliability of the design approaches. While the earth pressure approach was unreliable, exhibiting bias with pile slenderness and sand relative density, the CPT methods were shown to provide improved and relatively consistent estimates of pile capacity. However, the tension loads experienced by wind turbine foundations are significantly higher than those applied to piles in the database. When the CPT methods were used to estimate the pile length required to support a 5 MW turbine installed in typical offshore soil conditions, the CPT methods provided a wide range of predicted pile lengths. The reasons for this divergence are discussed and an alternative framework for considering driven pile shaft resistance is put forward.Deposited by bulk importTS 01.03.1