Contribution to the experimental study of an electrochemical measuring method of hydrodynamic quantities
Description
Electrochemical methods derived from polarography have already been used to study certain parameters of hydrodynamic flows. Unlike the previous methods, the technique that have been developed does not require the presence of an external source of direct current, as the electrodes-solution in motion assembly that is used operates as a battery and not as an electrolysis cell. In addition to some electrochemistry principles, the first chapter summarizes the previously used methods and presents the developed technique. In the second chapter, the theoretical study of mass transfer to the surface of a spherical cap is discussed. Under certain hypotheses, the equation of the material balance is solved using the equations of motion in the following two cases: - high Reynolds numbers, using the hypotheses of the boundary layer; - low Reynolds numbers, using a numerical resolution approaching the equations of Navier-Stokes. The third chapter presents the experimental study of the phenomenon: after the description of test conditions, it deals with the realization of the probes and their calibration in order to measure the local average velocity within a flow. Since these probes are of hemispherical configuration, it is possible to compare the experimental results obtained with the theoretical values deduced in the previous chapter. The application of the method to the measurement of local friction in the case of a runoff flow on the surface of an inclined plane is the subject of a study described in chapter IV. Finally, the chapter V evaluates the error introduced by the pins on the measurement carried out using a hot-wire anemometer probe, placed in a flow with a velocity gradient. To do this, a very long wire is used, which only a small portion (located away from the brackets) is not chemically insulated from the moving liquid. Disruptive pins can be placed at each ends of this non-insulated segment. Measurements carried out in the absence then in the presence of the two pins allow to know the influence of these pins.
Abstract (French)
Plusieurs experimentateurs ont deja fait appel a des methodes electrochimiques derivees de la polarographie pour etudier certains parametres d'ecoulements hydrodynamiques. A la difference des methodes precedentes, la technique que nous avons mise au point ne necessite pas la presence d'une source externe de courant continu, l'ensemble electrodes-solution en mouvement utilise, fonctionnant comme une pile et non en tant que cellule a electrolyse. Outre certains rappels concernant l'electrochimie, le premier chapitre est consacre a un resume des methodes utilisees anterieurement puis a la presentation de la technique mise au point. Au second chapitre, nous abordons l'etude theorique du transfert de masse vers la surface d'une calotte spherique. Sous certaines hypotheses, l'equation du bilan de matiere est resolue a l'aide des equations du mouvement dans les deux cas suivants: - nombres de Reynolds eleves, grace a l'utilisation des hypotheses de la couche limite; - faibles nombres de Reynolds ou il est fait appel a une resolution numerique approchee des equations de Navier-Stokes. Le troisieme chapitre est consacre a l'etude experimentale du phenomene. Apres la description des conditions d'essais, il traite de la realisation des sondes et de leur etalonnage en vue de la mesure de la vitesse moyenne locale au sein d'un ecoulement. Ces sondes etant de forme hemispherique, il est possible de comparer les resultats experimentaux obtenus avec les valeurs theoriques deduites au chapitre precedent. L'application de la methode a la mesure du frottement local dans le cas d'un ecoulement de ruissellement a la surface d'un plan incline fait l'objet d'une etude exposee au chapitre IV. Enfin, au chapitre V, nous avons essaye d'evaluer l'erreur introduite par les broches sur la mesure effectuee a l'aide d'une sonde anemometrique a fil chaud, placee dans un ecoulement presentant un gradient de vitesse. Pour cela, nous utilisons un fil metallique tres long dont seule une faible portion, situee loin des supports, n'est pas isolee chimiquement du liquide en mouvement. Des broches perturbatrices peuvent etre placees a chacune des extremites de ce segment non isole. Des mesures effectuees en l'absence puis en presence des deux broches permettent de connaitre 1' influence de ces dernieres.Files
49107622.pdf
Files
(5.8 MB)
| Name | Size | Download all |
|---|---|---|
|
md5:fc7975a6924ecac6c1c99800f7665381
|
5.8 MB | Preview Download |
Additional details
Additional titles
- Original title (French)
- Contribution a l'etude experimentale d'une methode de mesure electrochimique de grandeurs hydrodynamiques
Publishing Information
- Imprint Pagination
- 232 p.
- Report number
- FRNC-TH--10153
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 49107622
- Subject category
- S42: ENGINEERING; S37: INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; S46: INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- ACCURACY; ANALYTICAL SOLUTION; BOUNDARY LAYERS; CALIBRATION; ELECTROCHEMISTRY; ELECTROLYTES; FLUID FLOW; FRICTION; HEAT TRANSFER; HYDRODYNAMICS; MASS TRANSFER; MEASURING INSTRUMENTS; MEASURING METHODS; NAVIER-STOKES EQUATIONS; POLAROGRAPHY; REYNOLDS NUMBER; VELOCITY
- Descriptors DEC
- CHEMISTRY; DIFFERENTIAL EQUATIONS; DIMENSIONLESS NUMBERS; ENERGY TRANSFER; EQUATIONS; FLUID MECHANICS; LAYERS; MATHEMATICAL SOLUTIONS; MECHANICS; PARTIAL DIFFERENTIAL EQUATIONS
Optional Information
- Notes
- 44 refs.; Available from the INIS Liaison Officer for France, see the INIS webite for current contact and E-mail addresses; Also available from Service Commun de Documentation Universite de Poitiers - Campus 6 rue Jean Carbonnier Batiment A2 TSA 91101 86073 Poitiers cedex 9 (France)