Effect of surface blowing on aerodynamic characteristics of tubercled straight wing

Recent research proves that wings with leading-edge tubercles have the ability to perform efficiently in post-stall region over the conventional straight wing. Moreover, the conventional straight wing outperforms the tubercled wing at a pre-stall region which is quintessential. Even though tubercled wing offers great performance enhancement, because of the complexity of the flow, the trough region of the tubercled wing is more prone to flow separation. Henceforth, the present paper aims at surface blowing – an active flow control technique over the tubercled wing to enhance the aerodynamic efficiency by positively influencing its lift characteristics without causing any additional drag penalty. Flow parameters like blowing velocity ratios and the location of blowing were chosen to find the optimised configuration keeping the amplitude and frequency of the leading-edge tubercles constant as 0.12 c and 0.25 c respectively. Numerical investigations were carried out over the baseline tubercled wing and tubercled wing with surface blowing at various blowing jet velocity ratios 0.5, 1 and 2 over four different chordwise locations ranging from 0.3 c to 0.8 c.The results confirm that blowing at various x/c with different blowing velocity ratios performs better than the conventional tubercled wing. Comparatively, blowing velocity ratio 2 at 0.3 c shows peak performance of about 28% enhancement in the lift characteristics relative to the baseline model. Particularly, in the pre-stall region, 25–50% increase in aerodynamic efficiency is evident over the tubercled wing with surface blowing compared with the baseline case. Additionally,attempts were made to delineate the physical significance of the flow separation mechanism due to blowing by visualizing the streamline pattern.     

Structural evolution of cometary surfaces

Comets with a high content of organics and light molecules are expected under cosmic radiation to gain a relatively unreactive crust and less volatile material to some ten metres deep. Interstellar dust impacts act to loosen and turn over 1 cm of the surface. We discuss how far this accords with observations of cometary dust halos and new versus old comets. Two key material properties have emerged from recent studies. Firstly, the source of cometary volatiles is not ice in the sense of material with a single sublimation energy. Secondly, the particulates are not simply mineral dust but include much organic material, some of which undergoes chemical processing and exchanges with the gaseous environment. Consistent with these properties, a coherent crust rather than a mantle of loose grains would build up to cover much of the nucleus of periodic comets. It would consolidate by cooking in the solar radiation, especially at peak temperatures around perihelion. There are two disjoint surface phases: one of volatile material, the other the refractory crust, the former deepening into crater-like hollows over successive apparitions. The transition to non-volatile crust is unstable, subject to competing consolidation and disruption processes, and sensitive to seasonal changes. A comet dims and becomes asteroidal as the inert crust extends over the erosion craters, and may only be rejuvenated via collision with a boulder-sized impactor or perturbation of the orbit to smaller perihelion distance.     

The Onset of Long Term Modulation in the Heliosphere in Cycle 23

The combination of Voyager 1 (77.9 AU, 34.4° N) and Voyager 2 (61.2 AU, 24.5° S) at moderate heliolatitudes in the distant heliosphere and Ulysses with its unique latitudinal surveys in the inner heliosphere along with IMP 8 and other satellites at 1 AU constitutes a network of observatories that are ideally suited to study cosmic rays over the solar minimum of cycle 22 and the onset of solar activity and the long term cosmic ray modulation of cycle 23. Through 2000.7 there have been three well-defined step decreases in the cosmic ray intensity at 1 AU with the cumulative effect being in good agreement with the net decrease in cycle 21 at a comparable time in the solar cycle. Over this period the intensity changes at Ulysses are similar to those at 1 AU. In the distant heliosphere the initial decreases appear to be smaller than those at 1 AU. However the full effects of the interplanetary disturbances producing the most recent and largest step decrease in the inner heliosphere have not yet reached V-2. This revised version was published online in August 2006 with corrections to the Cover Date.     

Geomagnetic Core Field Secular Variation Models

We analyse models describing time changes of the Earth’s core magnetic field (secular variation) covering the historical period (several centuries) and the more recent satellite era (previous decade), and we illustrate how both the information contained in the data and the a priori information (regularisation) affect the result of the ill-posed geomagnetic inverse problem. We show how data quality, frequency and selection procedures govern part of the temporal changes in the secular variation norms and spectra, which are sometimes difficult to dissociate from true changes of the core state. We highlight the difficulty of resolving the time variability of the high degree secular variation coefficients (i.e. the secular acceleration), arising for instance from the challenge to properly separate sources of internal and of external origin. In addition, the regularisation process may also result in artificial changes in the model norms and spectra. Model users should keep in mind that such features can be mis-interpreted as the signature of physical mechanisms (e.g. diffusion). Finally, we present perspectives concerning core field modelling: imposing dynamical constraints (e.g. by means of data assimilation) reduces the non-uniqueness of the geomagnetic inverse problem.     

Installation and preliminary data analysis of Penang magnetic data Acquisition system (MAGDAS) in Malaysia

MAGDAS PEN was established on 19th September 2019 as one of the MAGDAS observatory arrays located at Universiti Sains Malaysia (USM) (5.15°, 100.50°). The main objective of the MAGDAS project is to monitor global electromagnetic and the ambient plasma density in the geospace environment. This installation has contributed to a better understanding of the Sun-Earth coupling system. This paper presents the installation process of one of the MAGDAS magnetometers named YU-8 T magnetic sensor and provides a preliminary analysis of geomagnetic HDZ components amplitude-time that was observed at PEN station. A one-month HDZ-geomagnetic field data was processed from 1st November to 30th November 2019. The daily variations with a consistent pattern in delta H geomagnetic field components are observed throughout the day with eastward electric field effects that are observed during solar peak hours. The delta H-component gradually increases around 0700LT and reaches the maximum reading at 1300LT with a range of value ~ 40-70nT. The value slowly decreases that started from 1400LT until the night time. The reading during the night time shows a constant variation with magnitude varies in between ?10nT to + 10nT. The average H-component value of the night time is used as the baseline for the observation system. Overall, the observed trends portray a good sign of solar quiet field and Sq with no solar-terrestrial disturbances.     

Modeling Particle Fluxes and Absorbed Dose for Protection from Cosmic Rays Using the SHIELD Transport Code

Cosmic Research - A special version of the SHIELD transport code has been developed intended for radiation protection purposes in space. The calculation of the fluxes of primary and secondary...