A Review of 60 Years of Rotor Hub Drag and Wake Physics: 1954–2014

Reich, David; Shenoy, Rajiv; Smith, Marilyn J.; Schmitz, Sven

doi:10.4050/jahs.61.022007

Cited by 11 publications

(10 citation statements)

References 19 publications

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“…The flow associated with the rotor hub of a rotorcraft (e.g. helicopter) has been a recognized problem for decades (Keys & Wiesner, 1975;Reich et al, 2016) due to the complex configuration of rotating, interacting bluff-body shapes (see Fig. 1) producing unsteady turbulent wakes.…”

Section: Introductionmentioning

confidence: 99%

Characterization of a canonical helicopter hub wake

2018

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The current study investigates the long-age wake behind rotating helicopter hub models composed of geometrically simple, canonical bluff body shapes. The models consisted of a 4-arm rotor mounted on a shaft above a 2-arm (scissor) rotor with all the rotor arms having a rectangular cross-section. The relative phase between the 2-and 4-arm rotors was either 0° (in-phase) or 45° (out-of-phase). The rotors were oriented at zero angle-of-attack and rotated at 30 Hz. Their wakes were measured with particle-image-velocimetry within a water tunnel at a hub diameter based Reynolds number of 820,000 and an advance ratio of 0.2. Mean profiles, fluctuating profiles and spectral analysis using time-series analysis as well as dynamic mode decomposition were used to characterize the wake and identify coherent structures associated with specific frequency content.The canonical geometry produced coherent structures that were consistent with previous results using more complex geometries. It was shown that the dominant structures (2 and 4 times per hub revolution) decay slowly and were not sensitive to the relative phase between the rotors.Conversely, the next strongest structure (6 times per hub revolution) was sensitive to the relative

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Section: Introductionmentioning

confidence: 99%

Characterization of a canonical helicopter hub wake

2018

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“…Slika 10 -Zavisnost koeficijenta otpora omponenti glave glavnog rotora od Rejnoldsovog brojaizvor [18] Slika 11 -Uticaj Rejnoldsovog broja na koeficijent parazitnog otpora -izvor [19] Što se tiče dalje dekompozicije izvora otpora na nivou glave glavnog rotora, može se zaključiti da ispitivanja koja se sprovode nisu standardizovana. Kao posledica toga imamo veliki broj naučnih radova baziranih na CFD istraživanjima ili na aerotunelskim ispitivanjima modela čiji se rezultati međusobno ne mogu upoređivati upravo zbog različitih modela.…”

Section: Slika 9 -Određivanje Koeficijenta Interferencijeunclassified

Single rotor helicopter parasite drag estimation in the preliminary design stage

Dodic¹,

Krstic²,

Rašuo³

2018

Tehnika

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UVODPreliminarna faza projektovanja helikoptera započinje inicijalnim dimenzionisanjem letelice na osnovu statističkih pokazatelja, da bi se tokom nje velikim brojem iterativnih ciklusa došlo do geometrijskih i aerodinamičkih karakteristika koje omogućavaju prelazak na narednu fazu, a to je detaljno projektovanje [1]. Sam postupak dimenzionisanja je istovremeno praćen primenom odgovarajuće teorije za procenu performansi, koju svaki proizvođač helikoptera razvija i unapređuje, a sve u cilju smanjenja troškova i skraći-vanja vremena potrebnog za razvoj (slika 1). Procena performansi u lebdenju ne predstavlja značajan problem, jer osnovni fizički modeli obezbeđuju solidnu tačnost sa greškom do 2%, dok je kod procene performansi prevashodno vezanih za horizontalni let, kao što su maksimalna brzina leta, maksimalni dolet, najduže trajanje leta itd., ta greška desetostruko veća, s tim da Adresa autora: Marjan Dodić, Univerzitet odbrane,

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“…The mesh, time step, turbulence model, algorithm selection, and other user-selected variables all have an impact on the solution. However, when applied appropriately, CSE tools can capture complex unsteady behaviours that drive vertical lift component design (6,7) .…”

Section: Introductionmentioning

confidence: 99%

Towards certification of computational fluid dynamics as numerical experiments for rotorcraft applications

2017

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Virtual Engineering (VE), also known as Model-Based Systems Engineering (MBSE), is necessary in both current operational engineering qualifications and to help reduce the costs of future vertical lift design and analysis. As computational power continues to provide increasing capability to the rotorcraft engineering community to perform simulations in both real time and off line, it is imperative that the community develop verification and validation protocols and processes to certify these methods so that they can be reliably used to help reduce engineering cost and schedule. Computational Fluid Dynamics (CFD) has become a major Computational Science and Engineering (CSE) tool in the fixed wing and vertical lift communities, but it has not been developed to the point where it is accepted as a replacement for testing in certification of new or existing systems or vehicles. Since the rise of modern CFD in the 1980s, the promise of CFD’s capabilities has been met or exceeded, but its role in certification arguably remains less prominent than projected. The ability to implement transformative technologies further drives the need for CFD in design. To meet CFD’s role in certification, several goals must be met to provide a true “numerical experiment” from which accuracies (error estimates), sensitivities, and consistent application results can be extracted. This paper discusses the progress and direction towards developing CFD strategies for certification.

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A Review of 60 Years of Rotor Hub Drag and Wake Physics: 1954–2014

Cited by 11 publications

References 19 publications

Characterization of a canonical helicopter hub wake

Characterization of a canonical helicopter hub wake

Single rotor helicopter parasite drag estimation in the preliminary design stage

Towards certification of computational fluid dynamics as numerical experiments for rotorcraft applications

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