scholarly journals Predicting Rotor Heat Transfer Using the Viscous Blade Element Momentum Theory and Unsteady Vortex Lattice Method

Aerospace ◽  
2020 ◽  
Vol 7 (7) ◽  
pp. 90
Author(s):  
Abdallah Samad ◽  
Gitsuzo B. S. Tagawa ◽  
François Morency ◽  
Christophe Volat
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Vortex Lattice ◽  
Ground Effect ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Blade Element

Calculating the unsteady convective heat transfer on helicopter blades is the first step in the prediction of ice accretion and the design of ice-protection systems. Simulations using Computational Fluid Dynamics (CFD) successfully model the complex aerodynamics of rotors as well as the heat transfer on blade surfaces, but for a conceptual design, faster calculation methods may be favorable. In the recent literature, classical methods such as the blade element momentum theory (BEMT) and the unsteady vortex lattice method (UVLM) were used to produce higher fidelity aerodynamic results by coupling them to viscous CFD databases. The novelty of this research originates from the introduction of an added layer of the coupling technique to predict rotor blade heat transfer using the BEMT and UVLM. The new approach implements the viscous coupling of the two methods from one hand and introduces a link to a new airfoil CFD-determined heat transfer correlation. This way, the convective heat transfer on ice-clean rotor blades is estimated while benefiting from the viscous extension of the BEMT and UVLM. The CFD heat transfer prediction is verified using existing correlations for a flat plate test case. Thrust predictions by the implemented UVLM and BEMT agree within 2% and 80% compared to experimental data. Tip vortex locations by the UVLM are predicted within 90% but fail in extreme ground effect. The end results present as an estimate of the heat transfer for a typical lightweight helicopter tail rotor for four test cases in hover, ground effect, axial, and forward flight.

scholarly journals A Numerical and Experimental Investigation of the Convective Heat Transfer on a Small Helicopter Rotor Test Setup

Aerospace ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 53
Author(s):  
Abdallah Samad ◽  
Eric Villeneuve ◽  
François Morency ◽  
Christophe Volat
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Performance Limits ◽  
Heat Transfer Correlation ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Effective Angle ◽  
Series Of Experiments ◽  
Correlation Parameters

In-flight icing affects helicopter performance, limits its operations, and reduces safety. The convective heat transfer is an important parameter in numerical icing simulations and state-of-the-art icing/de-icing codes utilize important computing resources when calculating it. The BEMT–RHT and UVLM–RHT offer low- and medium-fidelity approaches to estimate the rotor heat transfer (RHT). They are based on a coupling between Blade element momentum theory (BEMT) or unsteady vortex lattice method (UVLM), and a CFD-determined heat transfer correlation. The latter relates the Frossling number (Fr) to the Reynolds number (Re) and effective angle of attack (αEff). In a series of experiments carried out at the Anti-icing Materials International Laboratory (AMIL), this paper serves as a proof of concept of the proposed correlations. The objective is to propose correlations for the experimentally measured rotor heat transfer data. Specifically, the Frx is correlated with the Re and αEff in a similar form as the proposed CFD-based correlations. A fixed-wing setup is first used as a preliminary step to verify the heat transfer measurements of the icing wind tunnel (IWT). Tests are conducted at α = 0°, for a range of 4.76 × 105 ≤ Re ≤ 1.36 × 106 and at 10 non-dimensional surface wrap locations − 0.62 ≤ (S/c) ≤ + 0.87. Later, a rotor setup is used to build the novel heat transfer correlation, tests are conducted at two pitch angles ((θ) = 0° and 6°) for a range of rotor speeds (500 RPM ≤ (Ω) ≤ 1500 RPM), three different radial positions ((r/R) = 0.6, 0.75 and 0.95), and 0 ≤ S/c ≤ + 0.58. Results indicate that the fixed-wing Frx at the stagnation point was in the range of literature experimental data, and within 8% of fully turbulent CFD simulations. The FrAvg also agrees with CFD predictions, with an average discrepancy of 1.4%. For the rotor, the Ω caused a similar increase of Frx for the tests at θ = 0° and those at θ = 6°. Moreover, the Frx behavior changed significantly with r/R, suggesting the αEff had a significant effect on the Frx. Finally, the rotor data are first correlated with Rem (at each S/c) for θ = 0° to establish the correlation parameters, and a term for the αEff is then added to also account for the tests at θ = 6°. The correlations fit the data with an error between 2.1% and 14%, thus justifying the use of a coupled approach for the BEMT–RHT and UVLM–RHT.

Mechanical Augmentation of Convective Heat Transfer in Air

1975 ◽  
Vol 97 (4) ◽  
pp. 516-520 ◽  
Author(s):  
J. K. Hagge ◽  
G. H. Junkhan
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Convective Heat Transfer ◽  
Boundary Layers ◽  
Convective Heat ◽  
Convection Heat Transfer ◽  
Renewal Theory ◽  
Surface Renewal ◽  
Mechanical Removal ◽  
Blade Element

An experimental investigation was conducted into augmentation of forced convection heat transfer in air by mechanical removal of the boundary layer. A rotating blade element passing in close proximity to a flat plate convective surface was found to increase the rate of convective heat transfer by up to eleven times in certain situations. The blade element effectively scrapes away the boundary layer, thus reducing the resistance to heat flow. Parameters investigated include scraping frequency, scraper clearance, and type of boundary layer. Increased coefficients were found for higher scraping frequencies. Significant augmentation was obtained with clearance as large as 0.15 in. (0.0038 m) between the moving blade element and the convective surface. The technique appears most useful for laminar and transitional boundary layers, although some improvement was obtained for the turbulent boundary layers investigated. The simple surface renewal theory developed for scraped surface augmentation in liquids was found to approximately predict the coefficients obtained. A new relation is proposed which gives a better prediction and includes the effect of scraper clearance.

A Study on Estimation of Propulsive Power for Wing in Ground Effect (WIG) Craft to Take-off

2012 ◽  
pp. 43-51 ◽  
Author(s):  
A. Priyanto ◽  
A. Maimun ◽  
S. Noverdo ◽  
J. Saeed ◽  
A. Faizal ◽  
...  
Keyword(s):  
Vortex Lattice ◽  
Surface Effect ◽  
Aerodynamic Drag ◽  
Ground Effect ◽  
Lattice Method ◽  
Flight Tests ◽  
Vortex Lattice Method ◽  
Design Speed ◽  
Propulsive Power ◽  
Wing In Ground Effect

This paper estimated the propulsive power required for Wing in Ground effect (WIG) craft to take-off. The hull form design of the WIG craft incorporates a stepped planing triple hull, since the planing hull is well known to give result and assist in lifting off the water surface effect. In order to determine the power required for WIG craft to take-off, the craft prototype was built into 1 to 6 model scale. In numerical calculation, the required thrust motor of model to take-off was calculated by summation of water drag; aerodynamic drag and the weight of model. The water drag was estimated by Savitsky’s method, and the aerodynamic drag by a MATLAB programming based on Vortex Lattice Method (VLM). In the experiments, the relationship propeller RPM against thrust motor was obtained from the calibration tests. At the flight tests of the model, the propeller RPM of the model was measured to determine the total thrust motor and the propulsive power required to take-off by using the Froude’s Momentum Theory. The required propulsive power for craft scaled model was found to give the total thrusts of 33.85 N, and the effective power estimates required for WIG model to take-off per propeller was 128Watt at the design speed. It was also observed during most of the flight tests, the craft is attempting to enter into ground surface effect at design speed. Kertas kerja ini mengira jumlah kuasa bagi bot Wing in Ground effect (WIG) untuk terbang. Perekabentuk bot WIG menggunakan badan bot planing, yang terkenal untuk membantu dan mengangkat badan bot ke atas permukaan air. Dalam mendapatkan kuasa bagi bot WIG untuk terbang, model bot dibina dalam skala 1 berbanding 6. Pengiraan kuasa bagi model WIG adalah pengiraan jumlah rintangan model pada setiap halaju, terhadap tambahan rintangan udara, rintangan air dengan jisim model. Kaedah yang digunakan dalam pengiraan jumlah rintangan model adalah dua kaedah iaitu kaedah berangka dan eksperimen. Dari kaedah berangka, rintangan air telah dikira menggunakan simulasi Savitsky, dan rintangan udara telah dikira menggunakan simulasi MATLAB berasaskan kaedah Vortex Lattice Method (VLM). Dari kaedah eksperimen, ujian kalibrasi dilakukan terlebih dahulu untuk mendapatkan hubungan antara RPM melawan daya dorong. Kemudian ujian terbang dilakukan untuk mendapatkan RPM untuk setiap halaju model sebelum terbang. Nilai RPM daripada ujian ini digunakan untuk mendapatkan jumlah daya dorong daripada ujian kalibrasi dan jumlah kuasa didapatkan dengan menggunakan persamaan hukum Froude’s Momentum. Keputusan jumlah daya dorong bagi model diperlukan untuk terbang daripada dua kaedah adalah 33.85 N, dan jumlah kuasa untuk satu kipas iaitu 128Watt. Daripada pengamatan ujian terbang, model WIG telah terbang dalam Ground Effect (GE) di atas permukaan air.

Calculation of the Aerodynamic Forces on Automotive Lifting Surfaces

1985 ◽  
Vol 107 (4) ◽  
pp. 438-443 ◽  
Author(s):  
J. Katz
Keyword(s):  
Steady State ◽  
Vortex Lattice ◽  
Numerical Technique ◽  
Angle Of Attack ◽  
Ground Effect ◽  
Aerodynamic Forces ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Close Proximity ◽  
Lifting Surfaces

A numerical technique was developed to investigate the performance of automotive lifting surfaces in close proximity to ground. The model is based on the Vortex Lattice Method and includes freely-deforming wake elements. The ground effect was simulated by reflection and both steady and unsteady pressures and loads on various wing planforms were considered. Calculated results are presented for wings having both positive and negative incidences, with and without ground effect. Also the transient lift of a wing in a plunging motion was analyzed in ground proximity and at a negative angle of attack. Finally the periodic lift fluctuations on the front winglet of a racing car, due to its suspension oscillations, were calculated and found to exceed approximately twice the steady-state value.

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