Experiments are performed to understand the effects of surface orientation on the pool boiling characteristics of a highly wetting fluid from a flush-mounted, micro-porous-enhanced square heater Micro-porous enhancement was achieved by applying copper and aluminum particle coatings to the heater surfaces Effects of heater orientation on CHF and nucleate boiling heat transfer for uncoated and coated surfaces are compared A correlation is developed to predict the heater orientation effect on CHF for those surfaces

Heater orientation effects on pool boiling of micro-porous-enhanced surfaces in saturated FC-72

High-field superconducting solenoids have proven themselves to be of great value to scientific research in a number of fields, including chemistry, physics and biology. Present-day magnets take advantage of the high-field properties of Nb3Sn, but the high-field limits of this conductor are nearly reached and so a new conductor and magnet technology is necessary for superconducting magnets beyond 25 T. Twenty years after the initial discovery of superconductivity at high temperatures in complex oxides, a number of high temperature superconductor (HTS) based conductors are available in sufficient lengths to develop high-field superconducting magnets. In this paper, present day HTS conductor and magnet technologies are discussed. HTS conductors have demonstrated the ability to carry very large critical current densities at magnetic fields of 45 T, and two insert coil demonstrations have surpassed the 25 T barrier. There are, however, many challenges to the implementation of HTS conductors in high-field magnets, including coil manufacturing, electromechanical behavior and quench protection. These issues are discussed and a view to the future is provided.

High Field Superconducting Solenoids Via High Temperature Superconductors

Enhancement of pool boiling critical heat flux in dielectric liquids by microporous coatings

The blades that play a key role to collect wind energy are the most critical components of a wind turbine system Meanwhile, they are also the parts most susceptible to damage Structural health monitoring (SHM) system has been proposed to continuously monitor the wind turbine Nevertheless, no system has yet been developed to a stage compatible with the requirements of commercial wind turbines Therefore, full-scale structural testing is the main means available so far for validating the comprehensive performance of wind turbine blades It is now normally used as part of a blade certification process It also allows an insight into the failure mechanisms of wind turbine blades, which are essential to the success of SHM Furthermore, it provides a unique opportunity to exercise SHM and non-destructive testing (NDT) techniques Recognizing these practical significances, this paper therefore aims to carry out an extensive review of full-scale structural testing of wind turbine blades, including static testing and fatigue testing In particular, the current status in China is presented One focus of this review is on the failure mechanisms of wind turbine blades, which are vital for optimizing the design of themselves as well as the design of their SHM system Another focus is on the strengths and weaknesses of various SHM and NDT techniques, which are useful for evaluating their applicability on wind turbine blades In addition, recent advances in photogrammetry and digital image correlation have allowed new opportunities for blade monitoring These techniques are currently being explored on a few wind turbine blade applications and can provide a wealth of additional information that was previously unobtainable These works are also summarized in this paper in order to discover the pros and cons of these techniques

A review of full-scale structural testing of wind turbine blades

Author(s): Bazilevs, Y; Deng, X; Korobenko, A; Di Scalea, FL; Todd, MD; Taylor, SG | Abstract: In this paper, we combine recent developments in modeling of fatigue-damage, isogeometric analysis (IGA) of thin-shell structures, and structural health monitoring (SHM) to develop a computational steering framework for fatigue-damage prediction in full-scale laminated composite structures. The main constituents of the proposed framework are described in detail, and the framework is deployed in the context of an actual fatigue test of a full-scale wind-turbine blade structure. The results indicate that using an advanced computational model informed by in situ SHM data leads to accurate prediction of the damage zone formation, damage progression, and eventual failure of the structure. Although the blade fatigue simulation was driven by test data obtained prior to the computation, the proposed computational steering framework may be deployed concurrently with structures undergoing fatigue loading.

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Isogeometric Fatigue Damage Prediction in Large-Scale Composite Structures Driven by Dynamic Sensor Data

The U.S. National High Magnetic Field Laboratory 100 Tesla multi-pulse magnet system is now successfully commissioned. This magnet system is the result of a long-term partnership project jointly funded by the U. S. Department of Energy - Office of Basic Energy Science and the National Science Foundation. Science experimentation inside the magnet started in December 2006 at the NHMFL Pulsed Field Science Facility located at Los Alamos National Laboratory. Repeated, non-destructive operation of the system with original components is continuing in the 85 T to 90T range. The system will eventually combine a nominal 40 T platform field produced by a controlled-waveform generator-powered long-pulse magnet with a nominal 60 T field generated by a capacitor-bank powered pulsed insert magnet to produce the rated field. Milestone non-destructive operation to 88.9 T was achieved in October 2006. This paper will present an overview of the generator driven outsert magnet system together with the high-field pulsed insert magnet's design and construction. We will review commissioning and performance data through summer of 2007. Criteria for increasing the systems maximum field performance will also be reviewed addressing the goal to increase operating field level (in support of experiments) to 95 T and then to 100 T.

Assembly, Commissioning and Operation of the NHMFL 100 Tesla Multi-Pulse Magnet System

The design, analysis and fabrication progress of the 100 T Multi-Shot Magnet is described. The description includes the structural analysis of the outer coil set, the fabrication of the 100 T prototype coil 1, the fabrication of a coil 1 test shell, and the analysis of the electrical busbar assembly. Fabrication issues and their solutions are presented. This magnet will be installed as part of the user facility research equipment at the U.S. National High Magnetic Field Laboratory (NHMFL) Pulsed Field Facility at Los Alamos National Laboratory.

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The U.S. NHMFL 100 Tesla multi-shot magnet

A new 75 T pulsed magnet design is now in evaluation at the NHMFL Pulsed Field Science Facility. The design incorporates improvements to the engineering template developed for the 65 T pulsed user magnets now at the NHMFL. The development of the 75 T magnet is part of the US-NSF effort to supply insert magnets for the DOE 100 T Multi-shot Pulsed Magnet Program. An important objective of the 75 T project is to gain experience operating insert-like coils at the same temperature, stress, and strain as will be encountered at 100 T. Two coaxially nested solenoid coils comprise the 75 T magnet. The windings are in series electrically. The inner "A" coil is constructed with materials & techniques identical to those planned for the 100 T inserts. We have successfully trained the 75 T prototype to full field over 21 pulses of increasing intensity. The capacitor bank energy for a 75 T pulse is 1.49 MJ. This paper presents a review of the magnet design, operational performance data, and the developments impact on the design of future pulsed field user magnets and inserts for the US-DOE 100 T Multi-shot Pulsed Magnet Program

Performance of 75 T Prototype Pulsed Magnet

Publisher Summary This chapter focuses on the development and the performance enhancement associated with the microporous coating in nucleate pool and flow boiling of highly wetting fluids, which are inert, dielectric, and can have low boiling points making them desirable for electronics cooling applications; however, their poor thermophysical properties require the use of heat transfer enhancement methods to provide a useful operating range. The microporous coating was developed specifically to enhance nucleate boiling performance in highly wetting fluids and to be benign enough for direct application to sensitive electronic chips. The microporous coating is a mixture of small particles (1- to 20-μm-diameter) and epoxy binder that creates a thin (≈50-μm thick), porous structure that contains re-entrant cavities. It is a surface treatment used to increase vapor/gas entrapment volume and active nucleation site density by forming a porous structure with cavities much smaller than conventional metallic porous coatings. Coating development improves incipience using re-entrant cavities and to enhance nucleate boiling heat transfer and critical heat flux (CHF) by significantly increasing the number of active nucleation sites. Under flow boiling conditions, the enhanced heat transfer benefit of the microporous coating depends on the boiling regime. In the boiling-dominated, subcooled convective boiling regime, the coating enables widespread subcooled boiling, thus providing significant heat transfer enhancements. The chapter discusses the development, optimization, and performance of the microporous coating and also highlights the physics behind the enhancement provided by the microporous coating.

A New Microporous Surface Coating for Enhancement of Pool and Flow Boiling Heat Transfer

An electromagnet coil comprising Litz wire windings and power leads without break or interruption is cooled by a perfluorinated liquid by sensible and phase change heat transfer in a closed system. The electromagnet coil may be housed in a pentagonal or hexagonal pressure vessel to allow high packing densities in an array or helmet configuration. The helmet is then lowered over a human cranium for transcranial electromagnetic stimulation. The Litz wire windings reduce the power and voltages required for operation, yet allow production of over 2 T of accurately directed magnetic pulses for direct nerve or neuron stimulation. The perfluorinated liquid maintains the temperature of the helmet to less than 35-40° C., ensuring a comfortable temperature device for a human test subject. A utility cable connects the helmet to an external cooling unit and an external power supply.

Curtt N. Ammerman

Papers

Assembly, Commissioning and Operation of the NHMFL 100 Tesla Multi-Pulse Magnet System

The U.S. NHMFL 100 Tesla multi-shot magnet

Performance of 75 T Prototype Pulsed Magnet

A New Microporous Surface Coating for Enhancement of Pool and Flow Boiling Heat Transfer

Apparatus and method for transcranial and nerve magnetic stimulation