Published April 26, 1985 | Version v1
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Calculation of the flow around thin structures by the singularities method: development of the principle of minimization and applications to different sub- and partially cavitating configurations

Creators

Description

A non-linear computation method to treat flows around thin structures has been developed. The introduction of the principle of minimizing leakage flow errors has made it possible to maintain first order integral methods, which is of interest for IT costs. The method gives access to the real values of the pressure coefficient at the leading edge, which is essential for predicting the risk of occurrence of cavitation. In a two-dimensional flow, the case of partially cavitating thin profiles has been treated. The nonlinear calculation of the pocket geometry was performed using an iterative procedure. The efficiency of the method allowed the calculation to be extended to the case of confined flows (tunnel and blade grid). The method was validated by comparisons made in a sub-cavitating flow with analytical results and standard results. In the case of the blade grid, the results were compared with results obtained by a finite element method. In all cases, the concordance of the results is excellent. In three-dimensional flow, the case of a wing of finite span was made using a simplified wake. The method was fully validated by the comparisons made with the standard results of the study. The configuration of the flow around the wing, especially in the region of the leading edge is in perfect agreement with what is known for sub-cavitating wings. In the case of the flow around the propeller, the differences observed with respect to the experimental results can be explained by the following facts: - the hub of the propeller has not been taken into account - the shape of the wake is of a very simplified one. The second reason is essential if one wants to have a good adequacy of the results compared to the experimental results. It is conceivable, in the near future, to introduce the hub of the propeller by a single layer distribution and a contracted propeller wake of the Kerwin type. At the end of this process, the treatment of the unsteady problem in sub-cavitating configuration can be treated; it will then remain to examine the problem of cavitation in steady state then unsteady state

Abstract (French)

La presente etude a permis de mettre au point une methode de calcul non lineaire permettant de traiter l'ecoulement autour de structures minces. L'introduction du principe de minimisation des erreurs commises sur le debit de fuite a permis de conserver des methodes integrales du premier ordre, ce qui est interessant pour les couts informatiques. La methode permet d'avoir acces aux vraies valeurs du coefficient de pression au bord d'attaque, ce qui est essentiel pour la prevision du risque d'apparition de la cavitation. En ecoulement bidimensionnel, le cas des profils minces partiellement cavitants a ete traite. Le calcul non lineaire de la geometrie de la poche a ete realise a l'aide d'une procedure iterative. L'efficacite de la methode a permis d'etendre le calcul au cas des ecoulements confines (tunnel et grille d'aube). La methode a ete validee a l'aide de comparaisons effectuees en ecoulement subcavitant avec des resultats analytiques et des resultats etalons. Dans le cas de la grille d'aube, les resultats ont ete confrontes a des resultats obtenus par une methode d'elements finis. Dans tous les cas, la concordance des resultats est excellente. En ecoulement tridimensionnel, le cas de l'aile d'envergure finie a ete realise a l'aide d'un sillage simplifie. La methode a ete parfaitement validee par les comparaisons effectuees avec les resultats etalons de l'etude. La configuration de l'ecoulement autour de l'aile, notamment dans la region du bord d'attaque est en parfait accord avec ce que l'on connait des ailes subcavitantes. Dans le cas de l'ecoulement autour de l'helice, les differences observees par rapport aux resultats experimentaux peuvent s'expliquer par les faits suivants: - le moyeu de l'helice n'a pas ete pris en compte - la forme du sillage utilise est une forme tres simplifiee. La deuxieme raison est essentielle si on veut avoir une bonne adequation des resultats par rapport aux resultats experimentaux. Il est envisageable, dans un futur proche, d'introduire le moyeu de l'helice par une distribution de simple couche ainsi qu'un sillage d'helice contracte du type Kerwin. Au terme de cette etape, le traitement du probleme instationnaire en configuration subcavitante pourra etre traite; il restera alors a examiner le probleme de la cavitation en regime stationnaire, puis instationnaire

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Additional details

Additional titles

Original title (French)
Calcul de l'ecoulement autour des structures minces par la methode des singularites: developpement du principe de minimisation et applications a differentes configurations sub- et partiellement cavitantes

Identifiers

URL
http://www.iaea.org/inis/Contacts/;

Publishing Information

Imprint Pagination
169 p.
Report number
FRNC-TH--10440

INIS

Country of Publication
France
Country of Input or Organization
France
INIS RN
50064696
Subject category
S42: ENGINEERING; S97: MATHEMATICAL METHODS AND COMPUTING;
Resource subtype / Literary indicator
Thesis
Descriptors DEI
AERODYNAMICS; AIRFOILS; CALCULATION METHODS; CAVITATION; COMPARATIVE EVALUATIONS; FLOW MODELS; FLUID FLOW; GAS FLOW; HELICAL CONFIGURATION; LIMITING VALUES; NONLINEAR PROBLEMS; PRESSURE DEPENDENCE; SINGULARITY; THREE-DIMENSIONAL CALCULATIONS; TURBINE BLADES; TWO-DIMENSIONAL CALCULATIONS; VALIDATION
Descriptors DEC
CONFIGURATION; EVALUATION; FLUID FLOW; FLUID MECHANICS; MATHEMATICAL MODELS; MECHANICS; TESTING

Optional Information

Notes
37 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS-NKM website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/; Also available from Bibliotheques Universitaires Grenoble Alpes 1130 avenue Centrale 38400 Saint-Martin-d'Heres (France)