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A two-dimensional mathematical model estimating the torque of a Halbach Array surface permanent magnet (SPM) motor with a non-overlapping winding layout is developed. The magnetic field domain for the two-dimensional (2-D) motor model is divided into five regions: slots, slot openings, air gap, rotor magnets and rotor back iron. Applying the separation of variable method, an expression of magnetic vector potential distribution can be represented as Fourier series. By considering the interface and boundary conditions connecting the proposed regions, the Fourier series constants are determined. The proposed model offers a computationally efficient approach to analyze SPM motor designs including those having a Halbach Array. Since the tooth-tip and slots parameters are included in the model, the electromagnetic performance of an SPM motor, described using the cogging torque, back-EMF and electromagnetic torque, can be calculated as function of the slots and tooth-tips effects. The proposed analytical predictions are compared with results obtained from finite-element analysis. Finally, a performance comparison between a conventional and Halbach Array SPM motor is performed.

With all the emphasis today on the economics of improving well costs, the industry is faced with finding a way to provide marketable technology to drill more challenging wells even cheaper. The top drive stands out as one of a few key pieces of equipment in the critical path. As a result Top Drive failures have accounted for a large portion of down time, thereby increasing costs to drill a well, and the top drive is in essence "the drill" needed to reach reservoirs that are farther and deeper than once thought possible.ExxonMobil needed to upgrade its drilling platform in the Yastreb field in order to reach reservoirs with very long, extended reach. Drilling these wells necessitated a need for more torque and speed. Typically these parameters are supplemented with downhole motors. However, in extended reach wells, failure 5,000 -6,000 feet downhole costs up to a full day to retrieve the equipment and another full day to re-deploy the tool. With performance improvements to today's modern top drive, we have been able to increase torque and speed on the top drive and move that associated risk to the rig floor.Today's ultra-deepwater drilling necessitates durable, maintenance friendly top drives to off-set the high day rate and spread costs associated with these wells. For that, top drives in this environment have taken a step-change to increase durability with larger main thrust bearings, larger main shaft connections, heavy-duty link tilt function, etc. In addition to this increased focus on durability, these machines also need to be repaired quickly to get them running again. This has created a new generation focused on maintainability, and modularity.

Summary Presented is a steady-state computational-fluid-dynamics (CFD) analysis of flow through a thick sharp-edge annulus (i.e., an orifice integrated with a rigid concentric cylinder, creating annulus flow conditions). With the upstream Reynolds numbers up to 435,000, the fluid studied is water and the percentage of closure of the annulus system is bounded between 50 and 97%. The various annulus geometries necessary to quantify annulus flow are identified and investigated using CFD tools. For the flow entering the converging/diverging annulus, two parametric models are developed from CFD simulation results. The first model estimates the downstream/upstream-pressure ratio when choked flow is started. The second model estimates a discharge coefficient for the annulus system. Using these models, the annulus volumetric flow rate can be estimated for both choked- and unchoked-flow conditions. The utility of these models is later demonstrated on a pseudosteady-state annulus flow problem where the annular blowout preventer (BOP) is closing.

A new advanced two-dimensional hybrid analytical model of a segmented magnet linear actuator (MLA) comprised of surface permanent magnets (PM) is developed in this paper. This model is used to predict and evaluate the performance of the segmented MLA with proper correction on magnetic Flux Effects, validated by computational modeling. An MLA design with non-uniform PM segmentation was applied in this research to improve its performance compared with conventional radially magnetized MLA and uniform segmented Halbach Array based MLA. For MLA thrust force prediction, the previous published analytical model does not consider losses due to two observed magnetic Flux Effects: (1) the magnetic edge effect—the diminishing nature of the magnetic flux at the edge of the MLA, and (2) the observed magnetic interaction effect—the inconsistent peaks of individual magnetic flux lines, lower than the overall peak flux. In the proposed hybrid model for the segmented MLA, the shaft magnetic field distribution is based on a scalar potential theory subdomain method and the ring magnetic field is based on equivalent surface distributed currents. Collectively, these models are combined with three-dimensional finite element analysis (FEA), to estimate the magnetic thrust force. A data driven pole correction factor is introduced, based on the FEA computational database of three-dimensional MLA, to capture the losses associated with the magnetic flux, which is not considered in the analytical subdomain method. Finally, a normalized pole correction is proposed to generalize the model to different magnetic grades, different dimensional constraints, and varying magnet ratios of the segmented magnets. The developed model provides the design basis for manufacturing optimized force dense segmented MLAs for rotary to linear actuation, based on the force required for the application without the need for running FEA analysis after each design iteration, reducing costs and time required for the optimal design.