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UAV De-Icing System Airflow and Thermal Analysis

by Daniyal
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Article 1: Airflow and Thermal Analysis of UAV De-Icing Systems

The first of these two papers examines the technical challenges posed by the current age of unmanned aerial drones (UAVs). Finally, while conventional aircraft could rely on the pilot’s experience, instincts, and visual comparisons, the UAV, considering its technological advances, is blind in the sky when it comes to the health of its own operations and structures. Similarly, as one would expect, the gap between needs and technological prowess in the UAV is wide, owing to the fact that the invention is still relatively new to the industry. As a result, UAVs operating in different parts of the world, including Iraq and Afghanistan, started to experience a high rate of attrition owing to wing icing, which happens inevitably at high altitudes. As a result, the UAV manufacturers failed to anticipate the possibility that, owing to the pilotless configuration of the aircraft, it would be almost impossible for a UAV pilot to detect and conclude that icing was occurring, let alone attempt to prevent such an occurrence by implementing countermeasures. Furthermore, the investigation would delve at the usage of FEA as a way of resolving the engineers’ complicated problems.

UAV De-Icing System Airflow and Thermal Analysis

To incorporate such a high degree of improvement in a timely and cost-effective way, the engineers went back to the drawing board and used CAD (Computer Aided Design) to try to draw a more level of conclusion on the problem at hand. The researchers specifically used these methods to try to find out what CFD properties the wings have. CFD, or Computational Fluid Dynamics, was a means for engineers to attempt to have the best degree of defense against ice formation on the wings and surface areas of the related aircraft without needing to coat the whole aircraft with expensive, bulky, and essentially ineffective de-icing mechanisms. The general value of maximizing “bang for the buck” in terms of where the de-icing systems were actually deployed stemmed from the reality that the essence of the employment that the UAVs do and help necessitates them remaining aloft for extremely long periods of time. As a consequence, these planes must be as small as practicable while still being as fuel-efficient as possible. Similarly, using CAD and CFD to assess the parts of the aircraft were most susceptible to ice and its consequences was crucial in changing the aircraft thus enabling it to resume its missions without being fundamentally harmed.

Due to the constraints of time, money, weight, and a host of other factors, the engineers that engaged with the refits were ultimately reliant upon the ability of the engineers to co-opt different approaches and seek to engage with non-traditional means in order to ensure that the needs of the given project were met.  As a means of understanding this, one can and should realize that the methods employed by the engineers, inclusive of CAD and CFD, required them to approach the issue from different perspectives that were typically utilized only within various design stages. 

This utilization of CAD and CFD to draw inference upon the root issues allowed for the team to target and develop a unique approach to the issue at hand without having to start from the very beginning and redesign the aircraft.  Such an approach allowed for the team, as well as the ultimate shareholder, the taxpayer, to realize a net savings over any other approach that could have been engaged with.  Yet, although this represented a massive savings of both time and money, it is important for the reader/researcher to understand the nuanced approach that the issue was eventually and finally made aware to the engineers.  As such, the issue would, of course, have first been reported to the shareholders/officers that oversaw the use of UAVs within the theaters of war (Hutchinson 2).  Similarly, this news would have made its way up the chain of command and eventually to the highest level of purview that exist within the US military.  In this way, a needlessly high number of UAV crashes took place prior to the engineers being aware that there was an issue to deal with in the first place.  Although the way in which they responded and the relative speed within which they did so was exemplary, the dominating theme with regards to this is the level of more direct communication that needs to exist between the engineer and the end-user. 

Ultimately, based upon the needs that the aircraft symbolized, it was determined that there were two alternate approaches that could be taken; each with its own set of drawbacks.  The first of these was to install a meshed heating system under the wings to distribute heat; a means which has been in application within the realm of avionics since the early 1940s.  Due to the fact that such a traditional approach required such a large quantity of energy to supply the system with enough power to de-ice, the design engineers realized that it would be far more feasible as well as efficient to utilize a more useful system to superheat the front portions of the wings – thereby not allowing moisture to build up or accumulate.  Interestingly, how this was ultimately decided upon was by a FEM analysis of the mesh components that would need to be utilized in order to effect the greatest benefit on the wings and de-icing that could be realized.  In this way, the CAD, and CFD which the engineers utilized to draw a level of understanding on the key problem areas that manifested themselves within the aircraft’s surface could not have been realized had FEM not been put in use to map out a digital overlay of the key areas and allow these researchers/engineers to focus in upon them as a means of ameliorating the problem.

Article 2: Simulation of Heat Generation in Analyzing Thermoelastic Instability in Disk Brakes

As the author of the second article notes, one of the primary issues relating to the use, application, and effectiveness of traditional braking systems surrounds the ability of the braking mechanism to transfer the movement of the vehicle to heat energy and rapidly dissipate this energy so that the apparatus will again have an opportunity to function as it was designed.  As a means of better creating and utilizing a more efficient braking apparatus, researchers have once again turned to computer models to plot out the key areas in which heat dissipation is taking place, areas in which it could be improved upon, and ancillary areas in which little to no effect on the cars braking, heat dissipation, or other involved factors are necessary taking place.  As with the last example, an understanding of FEM and its application to the problem solving matrix that the researchers of this article engage with represents a fundamental component of how the issue itself was sought to be resolved.  One of the prime measurements that the engineers sought to utilize in this particular case a means of drawing inference upon FEM was TEI (or thermoelastic instabilities).

Ultimately, these TEIs represented the areas of the disc and/or brake pad that would most likely be likely to represent a weakness or failure within the braking apparatus.  However, more than merely representing a level of a failure, these TEIs also helped the engineers to infer what specific weak points exist within the mechanism.  The fact of the matter is, as the research describes, that the thermal properties of the braking system were able to be analyzed under the lens of the computer-assisted research to point out key spikes and anomalies in the way in which the braking system dispersed heat.  One of the ways in which this level of FEM was able to be understood was by providing the researchers with a never before seen view of how thermal “judder”, as the author dubs it, affects TEI.  This intermittent rubbing from the brake disc pad causes a type of heat buildup that is congruent with circular rings and or bubbles on the brake rotors.

Former understanding of the means by which the distribution of heat had been effected believed it to be concentric upon the midplane of the brake disc.  However, an examination of the TEI data via FEA software showed that heat transference was not integrally tied to the concentric of the brake’s midplane and was something which the researchers termed transient dispersal.  Through such a means of analysis, the researchers were further able to measure and determine the key areas of failure and over-use that the brake disc, pad, and rotors experienced during the braking process.  Although each of these had undergone extensive testing via earlier methods, there were few that allowed for a more realistic and rapid approach to understanding the thermodynamics of the underlying issue than a review and analysis of FEM as it related to the problem. 

As a means of using this level of inference onto the chosen model, the researchers/engineers were able to rapidly compare and contrast the thermal properties of a large amount of substances to include, a litany of aluminum metal matrix composites, with regards to both their overall heat distribution properties as well as the overall representation the differential analysis helped to prove with relation to what aspects of the mechanism were at, or near tolerance/failure, and what possible improvements this could portend for future trials and development.

Ultimately, what this meant was that the researchers were able to develop a very close approximation of the way in which certain composites reacted to the same stresses that normal/average driving would represent.  Moreover, as a function of the FEM simulation that was performed within the given tests, the conceptual design of the brakes and discs were themselves able to be divided into two distinct parts.  The first of these was with regards to the thermal properties that the given compound engendered, and the second was with regards to the elastic properties.  As a function of this level of analysis and the implementation of FEM to achieve such a goal, countless man-hours of time and energy, as well as a large amount of money were doubtless saved (University of Florida 3). 

However, perhaps more helpful than any of the previously mentioned factors that have been discussed is the extent to which the inference which FEM allowed the engineers and researchers to gain allowed for a growth and differential with regards to the testing.  Rather than proceeding with a given point in mind and unalterably attempting to test each and every variant, the freedom that FEM and its inference gave to the team was the ability to develop and evolve as a function of the outputs with which the team of engineers were greeted with upon each successive phase.  Traditionally, allowed for a degree of evolution and or development within the testing phases would have required an inordinately longer and costlier process; however, as a function of the utilization of FEM, the researchers were able to save vast amounts of money as well as time.

Works Cited
  • Timothy, Hutchinson. “Airflow and Thermal Analysis of UAV De-Icing Systems :: Defense Tech Briefs.” Home :: Defense Tech Briefs. N.p., 1 Oct. 2012. Web. 3 Mar. 2013. <www.defensetechbriefs.com/component/content/article/14910>.
  • University of Miami Florida. “Simulation of Heat Generation in Analyzing Thermoelastic Instability in Disk Brakes :: NASA Tech Briefs.” Home :: NASA Tech Briefs. N.p., 1 Jan. 2007. Web. 3 Mar. 2013. <http://www.techbriefs.com/component/content/article/2018?start=1>.

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