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Animate (Biological) Debris
Published in Ahmed F. El-Sayed, Foreign Object Debris and Damage in Aviation, 2022
Aircraft operating from hot areas in Asia and Africa may encounter strikes with buffalos and cows. Examples for these are: Boeing B737-800 aircraft operated by Spicejet flight SG622 (Surat–Delhi), on June 11, 2014, during takeoff roll at Surat, the aircraft was at around 350 m from start of runway, the left engine of the aircraft hit a buffalo. There was substantial damage to the engine (the engine cowl was badly damaged and there were holes on the sides of engine), but there was no fire or injury to any person on boardB737-800 aircraft operated by LION AIR, flight number: LNI892, on August 8, 2013, departing from Sultan Hasanuddin Airport (WAAA) Makassar, at 1203 UTC to Djalaluddin Airport (WAMG) Gorontalo, Indonesia. As the aircraft touched down the runway the aircraft struck two cows which were crossing the runway. The aircraft hydraulic lines of the brake system and weight on wheel sensor were damaged.
Boundary layers, wakes and other shear layers
Published in Bernard S. Massey, John Ward-Smith, Mechanics of Fluids, 2018
Bernard S. Massey, John Ward-Smith
Separation may be prevented by accelerating the boundary layer in the direction of flow. Increased turbulence produced by artificial roughening of the surface will achieve this to some degree, but it is more effective either to inject fluid at high velocity from small backward-facing slots in the boundary surface or to extract slow-moving fluid by suction. A disadvantage of injecting extra fluid is that, if the layer is laminar, this process provokes turbulence, which itself increases the skin friction. The slotted wing (Fig. 8.21), which has been used for the control of separation on aircraft, rejuvenates the boundary layer on the upper surface with fast-moving air brought through a tapered slot. It is particularly effective at large angles of attack, for which separation would otherwise occur early in the boundary layer’s journey, and therefore it also helps to increase lift (Section 8.8.6). A cowl (Fig. 8.22) can similarly reduce the drag of a blunt body (such as an aircraft engine).
Subsonic Transport Aircraft
Published in G. Daniel Brewer, Hydrogen Aircraft Technology, 2017
The cooling flows listed in Table 4–8 were used in the cycle selection studies for the high temperature investigation. Maximum rotor inlet temperature was held constant at 3200°F, while cycle pressure ratio, FPR, and bypass ratio were varied. Booster stage pressure ratio was held constant at 1.45:1. All engine cycles were evaluated at cruise condition (35,000 ft and Mach 0.85) and cruise power setting where operating rotor inlet temperature is 3000°F. At the cruise condition, engine thrust minus cowl drag was held constant at 6000 lb. The exhaust regenerator was included in the cycle.
Hypersonic flight control considering parametric variations and VGI effects
Published in International Journal of Control, 2021
Hao An, Qianqian Wu, Hongwei Xia, Guangcheng Ma, Changhong Wang
Notwithstanding these encouraged progresses, there still exist open problems in the field of hypersonic flights, among which how to guarantee the permissible inlet condition for the scramjet over a wide operating range is a critical issue. In a low-Mach-number hypersonic flight, the traditional fixed geometry inlet (FGI) originally designed for specific Mach numbers cannot inhale sufficient airflow due to the separation of shockwave from the cowl lip and the spillage of airflow (Bolender & Doman, 2007), causing an instantaneous loss of the precompressed airflow or even the fatal engine out. At the extremely high Mach numbers, the FGI may cause remarkable total pressure loss, boundary-layer separation and then scramjet unstart because the ramp shocks move inside of the inlet along with a strong incident shock (Zhang, Tan, Sun, Chen, & Li, 2017). A possible and effective solution to this problem is the cutting edge variable geometry inlet (VGI, whose typical shape is shown as Figure 1), which adjusts its geometry automatically according to the requirement of the onboard VGI management system (Bolender & Doman, 2007). So far, the VGI has been tentatively applied in engineering with some reported examples like the variable-length spike for the hypersonic axisymmetric inlet (Maru, Kobayashi, Takeuchi, & Sato, 2007) and the rotatable cowl lip for the X-43A hypersonic vehicle (Peebles, 2008).
Rail height effects on safety performance of Midwest Guardrail System
Published in Traffic Injury Prevention, 2018
Mojdeh Asadollahi Pajouh, Ramen D. Julin, Cody S. Stolle, John D. Reid, Ronald K. Faller
The Commentary portion of MASH describes the governing philosophy supporting the application of “practical worst-case impact conditions” American Association of State Highway and Transportation Officials (2016, p. 2). It is expected that low cowl and front engine hood heights of small cars are critical features that likely maximize the propensity for barrier underride and vehicle snag on support posts. Thus, vehicle front-end geometries were investigated for 451 passenger cars sold between 2005 and 2011 to identify vehicles more susceptible to underride below tall guardrails (NHTSA Vehicle Crash Test Database n.d.), as summarized in Table A1 (see online supplement), sorted by the average cowl height. Vehicle profiles have progressed from a box-shaped, rectangular front end to a sharp, wedge-shaped front end with increased “beltline” (i.e., lower windowsill) and cowl heights. Average passenger car cowl heights increased steadily from 883 mm (34¾ in.) to 965 mm (38 in.) between 1975 and 2012. Meanwhile, front hood heights only increased from an average of 691 mm (27.2 in.) between 1990 and 1994 to 739 mm (29.1 in.) between 2010 and 2012. Because some vehicle measurements were not available for Geo Metros, the known dimensions were compared to the other vehicles with similar low-profile, small car body types. It was found that the Geo Metro vehicle was approximately the same size as an early 1990s Honda Civic, for which summary information was available.
Numerical Investigation on Performance of Axisymmetric Variable Geometry Scramjet Combustor Equipped with Strut Flame Holder
Published in Combustion Science and Technology, 2023
Hongchao Qiu, Junlong Zhang, Guangjun Feng, Juntao Chang, Wen Bao
For the advantages of high specific impulse and high speed, scramjet is regarded as one of the most efficient air-breathing propulsion devices in supersonic flight conditions (An et al. 2020; Curran 2001; Huang 2018; Jiang et al. 2020; Karaca et al. 2019). Working in a wide range of the flight Mach numbers is an important problem for scramjet, and it has been widely investigated in many countries (Dai et al. 2018; Eldrainy et al. 2011; Sunami et al. 2002; Tian et al. 2015). Combustor is the key component of a scramjet (Chang et al. 2018; Liu et al. 2020; Xiong et al. 2020), and the performance of combustor has a great influence on the thrust of scramjet(TiGerlinger et al. 2008; Meng, Gu, Zhang 2019; Tian et al. 2020; Wang et al. 2013; Yang et al. 2020). One way of increasing the working range of the dual-combustor is to change the heat release position by adjusting the fuel distribution(Hu, Wen, Chang 2015; Meshcheryakov and Yashina 2015; Zhao et al. 2018) and the thermal throats are formed in different possion in the fixed-geometry combustor. This method is uesd in many programs, for example: French PREPHA program (Bouchez et al. 1998; Falempin et al. 2013), JAPHAR program (Dessornes and Scherrer 2005; Eggers, Novelli, Haupt 2001), and TRRE engine(Wei et al. 2017; Yang et al. 2017). Another method is to take the variable geometry.(Feng et al. 2017a, 2017b; Li et al. 2007; Liu et al. 2016). The flow matching can be realized by changing the combustor area with this variable geometry combustor. A combustor by moving the engine cowl to change the area of the combustor was proposed by the French and Russian (Bouchez et al. 2011; Falempin and Serre 2011; Falempin et al. 2006; Serre and Falempin 2003) since 2003.