Installed antenna performance in airborne radomes of different profiles

In this paper, broadband interactions between an antenna and a radome are modelled using a full wave numerical solver. By accurately describing both the antenna and the radome geometry with a single numerical method, a comprehensive prediction of the performance of the coupled antenna and radome installation is provided. The paper compares how different airborne dielectric radome profiles affect the antenna performance, predicting effects not seen in uncoupled simulations

Experimental benchmarking of Unstructured Transmission Line Modelling (UTLM) method in modelling twisted wires

In this paper the Unstructured Transmission Line Modelling (UTLM) method based on a tetrahedral mesh has been applied to modelling of the coupling between a single wire and a twisted wire pair. The effects of wire twisting on the crosstalk and coupling between wires are modelled by explicitly meshing wire geometries; simulation results are compared with experimental ones. Excellent agreement between simulated and measured results validates the viability and accuracy of the UTLM method and indicates the potential of the UTLM method for modelling complex wire structures

Experimental benchmarking of Unstructured Transmission Line Modelling (UTLM) method in modelling twisted wires

In this paper the Unstructured Transmission Line Modelling (UTLM) method based on a tetrahedral mesh has been applied to modelling of the coupling between a single wire and a twisted wire pair. The effects of wire twisting on the crosstalk and coupling between wires are modelled by explicitly meshing wire geometries; simulation results are compared with experimental ones. Excellent agreement between simulated and measured results validates the viability and accuracy of the UTLM method and indicates the potential of the UTLM method for modelling complex wire structures

Numerical investigation of nanoparticle deposition in a microchannel under the influence of various forces and development of a new correlation

Nanofluid-microchannels have gained prominence in recent years as a means of cooling electronic devices; however, nanoparticle deposition remains a challenge. In this paper, a discrete phase model (DPM) is used to study the effects of various forces on nanoparticle deposition of Al2O3-water nanofluids in a straight microchannel. The results indicate that Brownian motion has a significant impact on nanoparticle deposition. For instance, when Cunningham values vary from 1.2 to 0.2, nanoparticle deposition ratios decrease from 8.69% to 3.41%. When the fluid velocity is <0.6 m/s, the thermophoretic force becomes crucial, whereas Saffman's lift force becomes important when the particle diameter is <10 nm. In addition, gravity and pressure gradient forces can be ignored. Virtual mass and drag forces impact deposition indirectly by changing residence times. Finally, a new correlation has been proposed for calculating particle deposition ratios

Numerical investigation of nanofluid deposition in a microchannel cooling system

Nanofluid-microchannels (NF-MCs) have emerged as an important topic for thermal management of electronic devices. However, deposition of nanoparticles is a tricky problem, and this paper conducts a numerical study to identify the best working conditions to prevent deposition of nanofluids in a microchannel cooling system. According to the findings, large nanoparticles, high velocity, low inlet temperature, high nanoparticle density, low nanofluid density, and high base fluid viscosity are the best working conditions for improving nanofluid stability. However, heat transfer rates and pressure drop must also be taken into account. The nanoparticle deposition rate and average heat transfer coefficient only increase by 2.71% and 0.92% respectively as the heat flux increases from 20 kW/m2 to 100 kW/m2, but the pressure drop decreases by 10.57%. Therefore, changing the heat flux is not the best option. Moreover, the inlet temperature has only a minor effect on the heat transfer coefficient, so it is crucial to balance the pressure drop and nanoparticle deposition when designing systems

Numerical simulation of electromagnetic coupling in explicitly meshed wiring looms and bundles

In this paper, the Unstructured Transmission Line Modelling (UTLM) method based on a tetrahedral mesh is applied to model the electromagnetic coupling into wire looms and bundles with multiple cores that are typical of an aircraft system, when they are exposed to plane wave illuminations. The impact on the electromagnetic coupling into wires of both bundle configuration and the positioning of the bundle relative to simple structures are investigated using the UTLM method with explicit meshing of the wires. The work not only confirms that UTLM method as a powerful tool for dealing with wire looms and bundles but provides invaluable information on the margins to be expected in key experimental waveform parameters such as peak amplitude and frequency response

Space station propulsion system technology

Two propulsion systems have been selected for the space station: O/H rockets for high thrust applications and the multipropellant resistojets for low thrust needs. These thruster systems integrate very well with the fluid systems on the station. Both thrusters will utilize waste fluids as their source of propellant. The O/H rocket will be fueled by electrolyzed water and the resistojets will use stored waste gases from the environmental control system and the various laboratories. This paper presents the results of experimental efforts with O/H and resistojet thrusters to determine their performance and life capability