A millimeter-wave kinetic inductance detector camera for long-range imaging through optical obscurants

Millimeter-wave imaging provides a promising option for long-range target detection through optical obscurants such as fog, which often occur in marine environments. Given this motivation, we are currently developing a 150 GHz polarization-sensitive imager using a relatively new type of superconducting pair-breaking detector, the kinetic inductance detector (KID). This imager will be paired with a 1.5 m telescope to obtain an angular resolution of 0.09° over a 3.5° field of view using 3,840 KIDs. We have fully characterized a prototype KID array, which shows excellent performance with noise strongly limited by the irreducible fluctuations from the ambient temperature background. Full-scale KID arrays are now being fabricated and characterized for a planned demonstration in a maritime environment later this year

Forces on Obstacles in Rotor Wake – A GARTEUR Action Group

The paper describes the objectives and the structure of the GARTEUR Action Group HC/AG-22 project which deals with the basic research about the forces acting on obstacles when immersed in rotor wakes. The motivation started from the observation that there was a lack of experimental databases including the evaluation of the forces on obstacles in rotor wakes; and of both numerical and experimental investigations of the rotor downwash effects at medium-to-high separation distances from the rotor, in presence or without sling load. The four research centres: CIRA (I); DLR (D); NLR (NL); ONERA (F); and three universities: NTUA (GR); Politecnico di Milano (I); University of Glasgow (UK) created a team for the promotion of activities that could contribute to fill these gaps. In particular, both numerical and experimental investigations were proposed by the team to study, primarily, the effects of the confined area geometry on a hovering helicopter rotor, and, secondarily, the downwash and its influence on the forces acting on a load, loose or slung, at low to high separation distances from the rotor disc. The following activities were planned: a) application and possible improvement of computational tools for the study of helicopter rotor wake interactions with obstacles; b) set-up and performance of four cost-effective wind tunnel test campaigns aimed at producing a valuable experimental database for the validation of the numerical methodologies applied; c) final validation of the numerical methodologies. The project started in November 2014 and has a duration of three years

Void Fraction Measurment Beneath a Stationary Breaking Wave

Impedance based techniques have been used to quantify air entrainment by a stationary breaking wave at the bow of a ship. The present paper describes an impedance based void fraction meter which was developed to make measurements in this high speed, unsteady, multiphase flow, and details of its calibration are provided. In addition, air entrainment data from an experimental simulation of a bow wave are presented. The local, time averaged void fraction was mapped for flow cross sections beneath the plunging wave jet, revealing the location of the clouds of bubbles formed by that jet impacting the incoming water surface. Size distribution functions for the bubbles within the bubble clouds are also presented. The results are correlated with the wave structure described in Waniewski et al. (1997)

Evaluation of effectiveness of various devices for attenuation of trailing vortices based on model tests in a large towing basin

The effectiveness of various candidate aircraft-wing devices for attenuation of trailing vortices generated by large aircraft is evaluated on basis of results of experiments conducted with a 0.03-scale model of a Boeing 747 transport aircraft using a technique developed at the HYDRONAUTICS Ship Model Basin. Emphasis is on the effects produced by these devices in the far-field (up to 8 kilometers downstream of full-scale generating aircraft) where the unaltered vortex-wakes could still be hazardous to small following aircraft. The evaluation is based primarily on quantitative measurements of the respective vortex velocity distributions made by means of hot-film probe traverses in a transverse plane at selected stations downstream. The effects of these altered wakes on rolling moment induced on a small following aircraft are also studied using a modified lifting-surface theory with a synthesized Gates Learjet as a typical example. Lift and drag measurements concurrently obtained in the model tests are used to appraise the effects of each device investigated on the performance characteristics of the generating aircraft

Size-resolved aerosol and cloud condensation nuclei (CCN) properties in the remote marine South China Sea - Part 1: Observations and source classification

Abstract. Ship-based measurements of aerosol and cloud condensation nuclei (CCN) properties are presented for 2 weeks of observations in remote marine regions of the South China Sea/East Sea during the southwestern monsoon (SWM) season. Smoke from extensive biomass burning throughout the Maritime Continent advected into this region during the SWM, where it was mixed with anthropogenic continental pollution and emissions from heavy shipping activities. Eight aerosol types were identified using a k-means cluster analysis with data from a size-resolved CCN characterization system. Interpretation of the clusters was supplemented by additional onboard aerosol and meteorological measurements, satellite, and model products for the region. A typical bimodal marine boundary layer background aerosol population was identified and observed mixing with accumulation mode aerosol from other sources, primarily smoke from fires in Borneo and Sumatra. Hygroscopicity was assessed using the κ parameter and was found to average 0.40 for samples dominated by aged accumulation mode smoke; 0.65 for accumulation mode marine aerosol; 0.60 in an anthropogenic aerosol plume; and 0.22 during a short period that was characterized by elevated levels of volatile organic compounds not associated with biomass burning impacts. As a special subset of the background marine aerosol, clean air masses substantially scrubbed of particles were observed following heavy precipitation or the passage of squall lines, with changes in observed aerosol properties occurring on the order of minutes. Average CN number concentrations, size distributions, and κ values are reported for each population type, along with CCN number concentrations for particles that activated at supersaturations between 0.14 and 0.85 %

Rotor wake interactions with an obstacle on the ground

An investigation of the flow around an obstacle positioned within the wake of a rotor is described. A flow visualisation survey was performed using a smoke wand and particle image velocimetry, and surface pressure measurements on the obstacle were taken. The flow patterns were strongly dependent upon the rotor height above the ground and obstacle, and the relative position of the obstacle and rotor axis. High positive and suction pressures were measured on the obstacle surfaces, and these were unsteady in response to the passage of the vortex driven rotor wake over the surfaces. Integrated surface forces are of the order of the rotor thrust, and unsteady pressure information shows local unsteady loading of the same order as the mean loading. Rotor blade-tip vortex trajectories are responsible for the generation of these forces

Satellite measurement of ocean turbulence

Turbulence and mixing in the surface layer of the ocean is a significant element in the combined ocean-atmosphere system, and plays a considerable role in the transfer of heat, gas and momentum across the air-sea boundary. Furthermore, improving knowledge of the evolution of energy within the ocean system, both globally and locally, holds importance for improving our understanding of the dynamics of the ocean at large- and small-scales. As such, insight into turbulence and turbulent flows at the ocean surface is becoming increasingly important for its role in ocean-atmosphere exchange and, from a wider perspective, climate change.A research project was initiated to understand the role that spacecraft remote-sensing may play in improving observation of “turbulence” (in a broad sense) in the ocean, and for identifying how steps towards such observation may be made. An initial, exploratory study identified the potential benefit of Synthetic Aperture Radar in “bridging the gap” between in-situ and remote observations o

Airflow distortion at instrument sites on the RRS James Clark Ross during the WAGES project

Wind speed measurements obtained from anemometers mounted on ships are prone to systematic errors caused by the distortion of the airflow around the ship's hull and superstructure. This report describes the results of simulations of the airflow around the RRS James Clark Ross made using the computational fluid dynamics (CFD) software VECTIS. The airflow distortion at anemometer sites used during the WAGES project has been quantified at a wind speed of 10 m/s for relative wind directions of 0 (bow-on), 10, 20, 30, 50, 70, 90 and 110 degrees off the bow. The anemometers used in this study were located in the bows of the ship. Temperature sensors were located on the port side of the monkey island. For bow-on flows the anemometers in the bows of the ship experienced relatively small flow distortion. At these sites the flow was decelerated by about 1% of the free stream wind speed. Over the full range of relative wind directions the flow to the R3 sonic is generally accelerated with the largest wind speed biases at flows directly over the beam. The vertical displacement of the airflow increases from around 1 to 2 m for flows directly over the bow, to around 5m for flows over the ships beam as the blockage of the airflow by the ship becomes greater.The airflow distortion at the temperature sensor locations above the monkey island was typically greater than the well-exposed foremast locations. These locations experienced wind speed biases from 6% increase for an airflow directly over the bow, to large decelerations of 55 % when the instruments were in the large recirculation region for flows directly over the starboard side

An investigation into the development of an advanced ship performance monitoring and analysis system

PhD ThesisThe complete ban on TBT in marine antifouling coatings in 2008, rocketing fuel prices over the past six years, environmental concern and upcoming energy efficiency indices for ships have resulted in a strong interest of the shipping industry to monitor, evaluate and optimise ship performance. Furthermore, the complete ban on TBT in anti-fouling coatings resulted in new types of foul-release hull-coatings, based con silicon, whose effectiveness and performance still needs to be evaluated. Because of the difficulty of measuring coating roughness in service and the large effect of marine bio-fouling on ship performance, a research project was setup at Newcastle University in collaboration with a major paint company to investigate the ways to evaluate hull coating through ship performance monitoring. This thesis describes the details of this project which aimed to investigate the feasibility of a real-time ship performance monitoring and analysis (PM&A) system by implementation and evaluation onboard a 16m research vessel and 300.000dwt VLCC. The thesis starts with a review of the state of art of PM&A systems. The main weaknesses of existing PM&A systems is that often abstract logbook data is used as input and that too little attention is paid to data quality. Furthermore, the systems often act as a black box, showing little insight in data analysis, harming the reliability and trustworthiness of output indicators. Additionally, there are large differences in the way that performance data is corrected to standard conditions, resulting in contradicting and unreliable performance indicators. The thesis focuses therefore on theoretically sound, transparent data analysis and improved data collection. In the thesis, all performance affecting environmental and operational conditions have been reviewed including sensor characteristics and data acquisition aspects. Based on the experience from the analysis of the data collected from both vessels, it reveals that automatic, real-time data collection and rational filtering for periods of acceleration, deceleration, course deviation, drift, shallow water and ship motion is the way forward for accurate performance monitoring. Performance analysis is highly sensitive to errors in shaft torque and ship speed through water. A frequently calibrated/validated shaft torque & RPM sensor and Doppler speed log are therefore the most important sensors for performance monitoring. Speed logs are T.W.F. Hasselaar PhD thesis, 2010 ii affected by many environmental conditions and cannot be used directly for performance monitoring. Other ways to determine ship speed through water, e.g. using the propeller inflow speed, are however affected by hull fouling and loading deviations unless corrected for accordingly. Corrections using full scale trials are then necessary to avoid overestimation of the effects of hull fouling on ship performance. To avoid these errors, a method is described to use the speed log by evaluating its reliability and utilise its reading for performance analysis only in periods where it can be considered reliable. A new transparent analysis method is described to analyse ship performance based on conversion of torque and rpm at constant ship speed. The method differentiates between the hull and propeller performance by empirically correcting the propeller open water diagram for roughness (periodically measured by divers). Evaluation of the proposed PM&A system on both vessels indicates that reliable performance indicatgors can be calculated but that fluctuations in performance indicators of ±12% remain unavoidable due to inaccurate wave observations and errors from the speed log. Trials on the research vessel furthermore show that the system is able to identify fouling, but sensor accuracy requires further research so that fouling can be defined with less performance data and higher reliability. This thesis demonstrates for the first time in open literature that the design and implementation of a transparent and fully automatic, real-time, shipboard PM&A system is perfectly viable and can be installed on any ship with the use of reliable sensors.International Pain