Scoop Effects in Inclement Weather Operation

Venkataramani, Karthik; McVey, Leslie

doi:10.2514/6.2006-207

Cited by 8 publications

(4 citation statements)

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“…Water ingestion is one of the most common challenges that an aero‐engine needs to face and handle when aircraft is flying in inclement weather 1‐3 . Unfortunately, the raindrops concentration at engine inlet is higher than that in the atmosphere, because the scoop effect that occurs in flight descent must be taken into consideration 4 . More than 70% of droplets impinge on the cone and fan blades, where part of water droplets stick to their surface, and subsequently form a series of water films 5,6 .…”

Section: Introductionmentioning

confidence: 99%

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Unsteady performance and thermodynamic analysis of aero‐engine compressor at different water ingestion conditions

et al. 2020

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Summary Aero‐engine compressor is seriously threatened by the ingestion of liquid water. This article aims to deeply study the influences of different water contents and droplet diameters on the unsteady performance and thermodynamic parameters of compressor through frequency spectrum analysis. The accuracy of numerical calculation for compressor performance is verified by experimental data. Results show that the compression performance will be reduced and the unsteady fluctuations inside compressor will be aggravated after water ingestion. For some important parameters, such as mass flow rate, total pressure and temperature ratio, as well as efficiency, their main frequencies are changed from the original blade passing frequency to the rotor passing frequency (RPF), and their amplitudes are also significantly amplified. The working point of compressor will experience the nonoptimal state with large amplitude and period for a long time, which is not conducive to the stable operation of the compressor. Moreover, within the range of 2% to 8% water contents and 50 to 150 μm droplet diameters, the fluctuation amplitude is correspondingly exacerbated with the increase of water content or droplet size, but its main frequency is maintained at RPF. Particularly, the tip clearance is the most sensitive region affected by water ingestion where the fluctuations of static pressure and temperature are the largest. The point that water content has a greater influence on the performance fluctuation of compressor is also confirmed in this article.

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Section: Introductionmentioning

confidence: 99%

“…Therefore, the amplitude of the fluctuation can be better shown by subtracting the mean from each value. 4 The amplitude, A(f n ), is the maximum value that a fluctuating parameter can reach. The amplitude is defined for frequency f n in such ways:…”

Section: Fast Fourier Transform Introduction and Variable Definitionmentioning

confidence: 99%

Unsteady performance and thermodynamic analysis of aero‐engine compressor at different water ingestion conditions

et al. 2020

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“…3 This is so called the scoop effect in which the effective inlet area of air capture stream is relatively smaller than that of liquid water. 4 In the process of water ingestion, more than 70% of water droplets impinge on the cone and fan blades, where a series of water film form on their surface. 5,6 Although most of the incoming water is separated into the bypass duct by the action of centrifugal force and then discharged from the engine, there are still a significant amount of droplets entering the core compression system.…”

Section: Introductionmentioning

confidence: 99%

Evaluation on the performance fluctuation after water ingestion for a turbofan engine compressor during flight descent

Yang

Zheng

Lin

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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Turbofan engine compressor is most severely threatened by the entry of liquid water during flight descent. This study aims to deeply understand the fluctuations of compressor performance parameters caused by water ingestion through frequency spectrum analysis. The water content and droplet diameter distribution are determined based on the real heavy rain environment. Results reveal that most of the droplets actually entering the core compressor have a particle size of less than 100 μm. In addition, the formation and motion of water film plays a critical role in affecting the fluctuation characteristics. Water ingestion deteriorates the compression performance and aggravates the unsteady fluctuations of the fan. However, the performance of the core compressor is less affected by water ingestion, but their fluctuations are still exacerbated. For some important parameters, such as inlet mass flow rate, total pressure ratio, total temperature ratio, compression work and efficiency, their main frequency of fluctuation are switched from the original blade passing frequency to the rotor passing frequency, and their amplitudes are correspondingly amplified to varying degrees. These phenomena can be observed in both the fluctuations of the fan and core compressor. Moreover, the operating point of them will be in the long-period and large-amplitude fluctuations, which leads them experiences the non-optimal state for a long time and threatens their operating stability.

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“…This is called as the scoop effect in which the inlet area of airflow is relatively less than that of liquid water. 3 In addition, the existence of liquid water in the engine will pose some threats to the operational stability of compressor, combustion chamber, and turbine, which leads to local temperature reduction, pressure losses, mechanical losses, surge, and even flame-out. [4][5][6][7] It is obvious that the ingestion of water droplets will move together with the main airflow to the compression component.…”

Section: Introductionmentioning

confidence: 99%

Effects of water ingestion on the tip clearance flow in compressor rotors

Yang

Zhang

Lin

2018

Proceedings of the Institution of Mechanical Engineers, Part G:

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The tip region of compressor rotors may be filled with water when aircraft is flying in heavy rain environment. In order to explore the effects of water ingestion on the compressor performance and the characteristics of tip clearance flow, the Euler–Lagrange method has been utilized to simulate the two-phase flow inside a transonic rotor (NASA rotor 35). The typical trajectory of water droplet in compressor has been introduced firstly to simply understand the situation of water ingestion and to verify the reliability of some special droplet breakup models. The simulation results show that water droplets will change the distribution of airflow parameters along the span direction, which leads to the decrease of mass flow rate and the increase of attack angle at the tip region, as well as the separation of boundary layer on the suction surface. Furthermore, the momentum losses caused by droplet impingement and breakup directly causes a sharp increase in the static entropy at the blade tip region. On the other hand, the ingestion of droplet brings an external disturbance to airflow, and although it has some dissipated effects on the turbulence kinetic energy, it aggravates the unsteady characteristics of turbulent flow seriously at the tip region. Finally, by comparing the compressor performance under wet and dry states, it can be concluded that the pressure ratio and adiabatic efficiency of compressor decrease after water ingestion, and the compression efficiency drops by 1–2% on the whole while the operating point moves forward and the stable working boundary becomes narrow.

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Scoop Effects in Inclement Weather Operation

Cited by 8 publications

References 0 publications

Unsteady performance and thermodynamic analysis of aero‐engine compressor at different water ingestion conditions

Unsteady performance and thermodynamic analysis of aero‐engine compressor at different water ingestion conditions

Evaluation on the performance fluctuation after water ingestion for a turbofan engine compressor during flight descent

Effects of water ingestion on the tip clearance flow in compressor rotors

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