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What if the aviation industry contributed no carbon emissions?
Published in Nawal K. Taneja, Airimagination, 2023
Finally, while some airlines are thinking about the use of electric aircraft, some are also thinking about the use of supersonic aircraft. Leaving aside the question of the financial viability of a supersonic aircraft, there is also the question of its carbon footprint. Boom Technology claims that its supersonic aircraft, Overture, can achieve net-zero carbon emissions and should be able to operate on 100% sustainable fuel. United has ordered 15 with options to purchase another 35. Since supersonic aircraft are expected to fly at much higher altitudes than subsonic aircraft (e.g., at about 60,000 ft compared to about 35,000 ft), there is some concern about the level of emissions generated. Although at higher altitudes the air is thinner, producing less resistance, emissions generated from the supersonic aircraft, flying at higher altitudes, could also be higher than from the subsonic aircraft flying at lower altitudes. Nevertheless, imagine, if these supersonic aircraft took a significant percentage of business passengers out of corporate jets.
High-Speed Supersonic and Hypersonic Engines
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
Both Lockheed Martin (LMT) and Boeing (BA) are working with NASA to develop the Commercial Supersonic Technology (CST) project. Its objectives are developing the tools, technologies, and knowledge to help eliminate today’s technical barriers to practical commercial supersonic flight: sonic boom, fuel inefficiency, airport community noise, high-altitude emissions, and problems of aeroelasticity. The aim is to develop the ability to design future vehicles in an integrated, multidisciplinary manner. It is planned to have the first in a series of “X-planes” in NASA’s New Aviation Horizons initiative by the fiscal year 2017 budget. Moreover, NASA believes it is making good progress (largely through aircraft design), and sometime after 2022, it may be acceptable to exceed the speed of sound over land. That would put many more routes in play, and open the door to potential commercial supersonic service.
Blast, Fire, and Impact-Resistant Design
Published in Srinivasan Chandrasekaran, Advanced Steel Design of Structures, 2019
Quantum of energy, released into the atmosphere results in a pressure-transient wave or a blast wave. Further, it is important to note that the blast wave propagates outward in all directions from the source at a sonic or supersonic speed. Supersonic speed is defined as the rate of travel of an object exceeding the speed of sound. For objects traveling in dry air at a temperature of about 20°C, the supersonic speed is about 344 m/s, which is equivalent to 667 knots or about 1240 km/ho. The magnitude and shape of the blast wave depend upon the nature of the energy released and the distance of the object from the epicenter of the explosion. Blast waves are categorized into two: shock wave (S-waves) and pressure waves (P-waves).
Response surface analysis of nozzle parameters at supersonic flow through microjets
Published in Australian Journal of Mechanical Engineering, 2023
Turki Al-Khalifah, Abdul Aabid, Sher Afghan Khan, Muhammad Hanafi Bin Azami, Muneer Baig
Contour results will display the variation of any rejoinder concerning the input parameters. Hence, to analyse the base pressure variation for both with and without control, this study has been adopted. From Figure 10 (a & b), pressure in the separated area illustrates Mach number vs. NPR. A higher value of the base pressure is found at a lower NPR level and a higher Mach number level (lower right-side corner-dark green). In contrast, the base pressure reduction has been found in higher NPR and lower Mach number (top left corner-dark blue). This means the supersonic Mach number will decrease base pressure in the base region with larger values and increase downstream. Furthermore, when flow control is activated, this variation has been similar, only the values are slightly different.
Evaluation of breakup models for liquid side jets in supersonic cross flows
Published in Numerical Heat Transfer, Part A: Applications, 2020
Yang-Yao Niu, Chung-Hao Wu, Yu-Hsuan Huang, Yi-Ju Chou, Song-Charng Kong
The phenomena of supersonic flow over a liquid side jet were investigated numerically. Simulated results were validated using the experimental data by Lin, Kennedy, and Jackson in 2004 [2]. Figure 2 shows the computational domain and our simulation schematic diagram. In this study, water was chosen. The injector was located at with a diameter of the side jet (water) was injected into the supersonic flow of Mach number of and the pressure and temperature are and respectively. The gas-liquid momentum ratio is The corresponding mass flow rate is The grid number of the computational domain is in the x and y directions, respectively. The grid around the injector is the finest in order to resolve the details of the water injection. In the present simulations, large droplets were injected, with a fixed time interval between two droplets, to observed the droplet’s breakup characteristics and the interaction of the gas and liquid.
Numerical estimation of air core length in two-phase free surface vortex
Published in Journal of Hydraulic Research, 2019
Soo-Hwang Ahn, Yexiang Xiao, Zhengwei Wang, Hongying Luo, Yongyao Luo
On the basis of the characteristic of the sound speed, the isothermal water–air mixture can be characterized by three flow regimes: incompressible in pure water, compressible with low Mach number in pure air and with transonic or supersonic Mach number in the mixture. If the mixture flow is assumed to be isentropic, and the speed of sound can be defined as: The present work used the incompressible flow solver with homogeneous two-phase mixture modelling, which was not governed by the equation of state. Therefore, the local speed of sound was defined by the use of the chain rule, which could be expressed by the pressure and density gradients as follows: Figure 10 shows the correlation between the mixture sound speed and the water volume fraction in this simulation; here the mixture speed of sound amix was obtained at a vertical line on the axis of the cylindrical vessel for the volume flux of 7.5 l min−1. This indicates that the minimum amix is much lower than that of pure water. In this simulation case, the flow velocity is relatively low, and the mixture flow is mainly characterized by the subsonic flow. However, if the two-phase mixture is at higher Reynolds number or Mach number, the compressible characteristics would need to be taken into account.