Towards a sustainable aerogel airship: a primer

Airships are the first craft that realized mankind’s dream of controlled, powered flight but have been a forsaken method of air transportation since the invention of heavy-than-air aircraft. However, environmental concerns have urged humanity to think once again over the possibility of deploying these lighter-than-air ships. This paper describes an on-going project thereby a nature-inspired airship, namely Huvr Trek is being designed to address current airborne technological, economical and ecological gaps. It uses the world’s best thermal insulator and second lightest material, silica aerogel for inhibiting heat transfer within the balloon for efficient lift as well as in a prototype liquid-fuelled ramjet for propulsion. The airship uses carbon aerogels also as super capacitors for energy storage. Proposed applications of the aerogel airship are and implementations into advertising and tourism, surveillance, environmental monitoring, planetary exploration, cargo transportation, stratospheric observation, medical equipment carrier and telecommunication relay

Feasibility study of a novel aerogel-based thermally sprayed coating

Aerogels are sol-gel derived nanostructured ceramics with fascinating physical properties to the extent that they are sometimes recognised as a new state of matter. The lightest aerogel is now graphene aerogel followed silica aerogel, which is, still the best thermal insulator ever existed. In the aerospace arena or even in the most aerogel dominated industry which is oil and gas, the quest for ever-more efficient systems is largely pursued by minimising the weight and space without compromising the overall performance. As far as thermal insulation is concerned, silica aerogel has always been attributed with the notion of superinsulation due to its superior heat resistance compared to conventional materials. Innovative solutions have been brought forward thereby aerogel-based flexible glass-wool blankets and aerogel-doped paints have been developed and commercialised. This paper proposes a novel method of application wherein silica aerogel was thermally sprayed using atmospheric plasma spraying to produce a micro-thick coating on glass, for instance. Being a preliminary study, four pivotal spraying parameters were taken into account and trials were made by altering them in a systematic manner to obtain an adhering coating. The aerogel-based plasma sprayed coating formed had a maximum cross-sectional thickness ranging from 77.9 to 132.0 μm with spraying parameters of power, carrier gas flow, plasma gas (Ar+H2) and nozzle diameter of 25 kW, 8.1 slpm,(45+5) slpm and 4 mm respectively

Burn-through responses of aero-engine nacelle using fiber metal composites by ISO2685 propane-air burner

The paper presents experimental investigation on the behavior and burn through responses of a flat plate composite of fiber-metal laminates composites of aluminum alloy 2024-T3 with carbon and natural fibers subjected to environmental conditions in fire designated zone of an aircraft engine exposed to fire. The main purpose of this study is to know the different burn through time responses of different forms of aluminum alloy with synthetic and natural fibers. The composites were designed and developed to improve the flame fire resistance in a fire designated zone of an aircraft engine in near future for prolonged burning through time that will at least withstand the fire flame for 15 minutes according to the ISO 2685 standard. The composites are fabricated by hand lay-up method in a mold of 300 mm x 300 mm and compressed by compression machine. Based on the obtained results, some of the composites are indicated to be fireproof while some others are fire resistant. It is shown that the carbon fiber reinforced aluminum alloy laminate with only aluminum at top and bottom (CF+AA) of the composites can resist more flame temperature than the carbon fiber reinforced aluminum alloy laminate with alternate layers of aluminum and carbon fiber (CARALL) with 7.86%, the sandwich of carbon fiber with flax with 18.2% and the sandwich of carbon fiber with kenaf with 23.43%. In conclusion, the study reveals that aluminum alloy 2024-T3 with carbon fiber and some types of natural fibers composites possess good properties of resisting high temperature of fire designated zone of an aircraft engine nacelle

A two-component CFD studies of the effects of H2, CNG, and diesel blend on combustion characteristics and emissions of a diesel engine

Numerical simulations were conducted on a Ricardo Hydra diesel engine which is single cylinder engine and uses direct injection method. This study was performed by using a two-dimensional CFD code to examine the combustion characteristics and emissions of a diesel engine in diesel-CNG and diesel-H2 dual-fuel operations, as well as in the diesel-CNG-H2 tri-fuel operation at various air-fuel ratios. The results indicate that the peak in-cylinder pressure and peak temperature were increased with the addition of gaseous fuels at low and medium values of exceeds air. Compared with Diesel-H70-N30 for tri-mode and Diesel-H2 for dual mode, it is observed that there were no effects on the peak temperature at high exceed air. At 2.4 exceed air, the peak pressure increases by means of adding the limit value of hydrogen, such as H30-N70 and H50-N50, to CNG and it begins to decrease with H70-N30 and H2-Diesel operations. Diesel-H2-CNG operations decrease CO/CO2 emissions compared with Diesel-CNG operation and decrease NO emission compared with Diesel-H2 operation at every exceed air. The reduction in CO/CO2 emissions was suggested at high hydrogen fraction in CNG (H70-N30) with all exceeds air whereas low hydrogen fraction in CNG (H30-N70) can repress uncontrolled hydrogen combustion and further limit the increment of NO emission

Fluid flow and heat transfer over corrugated backward facing step channe

The convective heat transfer and flow field characteristics through a backward-facing step (BFS) channel combined with a corrugated wall is investigated numerically and experimentally. Uniform heat flux is applied on 200 mm of the downstream wall, while the rest of the walls are considered isolated surfaces. The range of Reynolds number (Re) of the flow was between 5000 and 20,000. The governing equations were solved using the RNG turbulent model. The effects of wavelength and amplitude height of the corrugated wall on the friction factor and Nusselt number are studied. The results indicated that the fluid flow in the BFS channel combined with the corrugated wall significantly enhanced the heat transfer with increased friction. The average increase in the heat transfer rate and friction factor in the experiment is 40.7% and 46.2% respectively. The simulation results are comparable to the experimental ones. According to the simulations, the channel with an amplitude height of 4 mm and a wavelength of 20 mm has the highest heat transfer enhancement, reaching a performance evaluation criterion factor of 1.33 at 5000 Re

Improvement of Mechanical Welding Properties by using Induced Harmonic Vibration.

The enhancement of the welding mechanical properties and the quality of the fusion metal is considered recently by using vibration during welding. In this study, the effect of induced harmonic vibration during welding is employed to improve the welding mechanical properties and to reach the best shape of welding line on the surface. The harmonic vibration method is examined experimentally by using four values of mechanical frequency during welding on the ductility, tensile strength and the homogeneity of the welding line. The frequencies were specified according to the natural frequency of the plate. Five simply supported rectangular plates are supported on the supporting stand and welded using a manual arc-welding machine. The experimental results show that the vibration applied during welding generally improved the bend property of the welding line, as well as the tensile strength has been improved distinctively at the resonance case when compared with that one welded without vibration. The morphology of the fillet metal after welding and for each value of frequency show an enhancement in the distribution of the fusion fillet metal, with gradually disappearing of the micro crack that may shown inside the metal with increasing the mechanical frequency. A comparison between the properties of welding without vibration and welding with vibration is discussed

Heat transfer enhancement of a Stirling engine by using fins attachment in an energy recovery system

Compared to other traditional engines, the Stirling engine is an externally closed heat engine loop with a high theoretical efficiency and low emissions. Due to its multi-fuel capacity, including solar, biogas and geothermal energy, this property is now becoming very advantageous. However, the performance of the Stirling engine is penalized when being integrated with a low heat source. Thus, research on enhancing the engine's performance through heat transfer is highlighted in this paper. A numerical investigation of the effect of circular, pin, and rectangular fins on the efficiency of the Stirling engine is presented in this report. The engine's model was analyzed using computational fluid dynamics (CFD) method and validated with previous study without any additional heat enhancement material. The result recorded an average of difference around 2.15% with other CFD models and 3.13% with experimental results. The engine's model is then added with fins. An increment in the heat transfer rate, efficiency and power output of the engine are obtained and the highest efficiency is achieved by rectangular fins with 19.03%

Numerical study on the turbulent mixed convective heat transfer over 2D microscale backward-facing step

The current numerical study investigated over two-dimensional (2D) flat microscale backward-facing step (MBFS). The boundary conditions and the controls fixed by the finite volume method (FVM) and RNG k-ε model. The upstream and the step of the wall considered adiabatic, while the downstream of the wall heated by constant heat flux. The straightforward wall of the channel fixed at a constant temperature that is higher than the fluid inlet temperature. The Reynolds number (Re) range of 5,000 ≤ Re ≤ 15,000 was used in the study. The results show that the increase in the Re will resulted in increased of Nusselt number (Nu). The study also found that the highest Nu was produced from the ethylene glycol case. The current study also found that the recirculating range at steps is more significant than using water under the same Re by using ethylene glycol

Aerogels in aerospace: an overview

Aerogels are highly porous structures prepared via a sol-gel process and supercritical drying technology. Among the classes of aerogels, silica aerogel exhibits the most remarkable physical properties, possessing lower density, thermal conductivity, refractive index, and dielectric constant than any solids. Its acoustical property is such that it can absorb the sound waves reducing speed to 100 m/s compared to 332 m/s for air. However, when it comes to commercialization, the result is not as expected. It seems that mass production, particularly in the aerospace industry, has dawdled behind. This paper highlights the evolution of aerogels in general and discusses the functions and significances of silica aerogel in previous astronautical applications. Future outer-space applications have been proposed as per the current research trend. Finally, the implementation of conventional silica aerogel in aeronautics is argued with an alternative known as Maerogel

Professional pathway for civil aviation authority of Malaysia (CAAM) aircraft maintenance license holder registered at BEM

This paper proposes a professional pathway for Civil Aviation Authority of Malaysia (CAAM) Aircraft Maintenance License Holder (AML) currently registered with the Board of Engineers Malaysia (BEM). It carries out a study on how the professional pathway enhances the AML holder professional development and complement CAAM functions. It highlights the importance of professional development and the importance of compliance of code of conduct as an aircraft maintenance engineering professional. The aircraft maintenance engineering professionals covered the holder of aircraft maintenance license non type rated category B1 and B2 registered as engineering technician, category B1 and B2 with type rating who is registered as engineering technologist and category C with type rating who is registered as graduate engineer at Board of Engineers Malaysia. Literatures were reviewed and reference to existing professional pathway practices of Engineering Council, United Kingdom through its licensed society such as Royal Aeronautical Society, United Kingdom was an example analyzed. This paper resulted in the proposal of professional development pathway for the CAAM AML holders who are registered at BEM various categories. This paper also clarifies that airworthiness certification of the CAAM AML holders are governed by CAAM. Professional registration of the CAAM AML holder at BEM ensures AML holders complies with the professional code of conduct and ethics as registered engineering professional such as professional engineer (P.Eng). It also ensure continuous professional development as BEM registered engineering personnel. The outcome shows that AML holder professional registration at BEM enhances the AML holder professional development and complement CAAM functions in achieving the Malaysian aerospace blueprint 2030 effectively