# Some problems in hydrodynamics and aerodynamics treated theoretically and experimentally

Sengupta, Sudhir Ranjan (1934) Some problems in hydrodynamics and aerodynamics treated theoretically and experimentally. PhD thesis, University of Glasgow.

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Printed Thesis Information: https://eleanor.lib.gla.ac.uk/record=b1629630

## Abstract

(1) Part I deals with flow of perfect fluid past the Grid for d/2c = 1/2 and for d/2c=2/3-, ie, with the solution of ▿ψ=0. Electrical analogy is applied to check the approximate solution obtained. Increase of electrical resistance of a plate of uniform thickness due to the presence of circular hole is obtained from theory and experiment. A method of estimating the increased velocity of flow past cylinder due to interference is given based on perfect fluid motion. (2) Part II deals with the arithmetical solution of viscous flow past the Grid d/2c =1/2 at Reynold's Number 20 There does not seem to exist a stationary eddy pair at this Reynold's Number. This is confirmed by photographing the wake of the cylinder of the Grid. (cf, case of Single Cylinder) Values of Kp, Kv and K"D are obtained from the above solution and are found to be higher than those for a single cylinder in infinite field at the same Reynold's Number. (3) Part III deals with the solution of Boundary Layer equation for the Grid d/2c = 1/2 at R = 85I The viscous drag coefficient Kv for a cylinder of the Grid d/2c = I/2 is found to be 2,4I/?R (4) Part IV gives an approximate estimate of the front generator pressure of a Cylinder of the Grid d/2c =I/2 based on Boundary Layer Theory. This is found to be greater than that for a single cylinder. Approximate estimate of this for the Grid d/2c = I/2 is also given from the experimental pressure curves. (5) Part VI deals with experiments. Pressure drag is calculated from pressure measurements round a Cylinder of the Grid d/2c = I/2. Total drags of a Cylinder of the Grid d/2c = I/2 and d/2c =3/I0 are obtained from direct force measurements. Total drag of Cylinder od the Grid d/2c = I/2 is also obtained by measuring the loss in total head. The drag coefficients are found to be greater than those for a single cylinder in infinite field. The viscous drag coefficient Kv for a cylinder of the Grid d/2c = I/2 as obtained from the experiments is found to be 3/√R as compared to 2/√R for single cylinder. (6) Part VII deals with the Karman Vortex Street behind the Grid. It is found to be unstable. (7) In Part VIII, the writer uses Rosenhead and Scwabe's particulars of Karman street behind a cylinder between channel walls to estimate the total drag coefficients for a clinder of Grid for different values of d/2c. (8) In Part IX an approximate expression for the total drag the ratio of the total drag coefficients of a cylinder of the Grid or for a cylinder between parallel walls to that of a cylinder in infinite field is given. (9) In Part X an alternative expression for the increased velocity of flow past cylinder due to interference, is given based on the increased drag coefficients. (10) In Part XI an approximate estimate of the Increased drag of a cylinder between channel walls, when the velocity distribution is parabolic is given.

Item Type: Thesis (PhD) Doctoral Related publication: Air Torque on a Cylinder Rotating in an Air Stream ARC/R and M-1520 Air Ministry. Aeronautical Research Committee. Reports and memoranda Issue 1520, Volume 3319 of Reports and memoranda / Great Britain, Aeronautical Research Committee. Authors: A. Thom ; S.R. Sengupta (student). T Technology > TL Motor vehicles. Aeronautics. Astronautics College of Science and Engineering Cormack, Professor J.D. 1934 Enlighten Team glathesis:1934-83102 Copyright of this thesis is held by the author. 29 Aug 2022 15:02 29 Aug 2022 15:02 10.5525/gla.thesis.83102 http://theses.gla.ac.uk/id/eprint/83102