Engineering topics

Fan, D.-N.

Publications and source records attributed to Fan, D.-N..

4 records

NASA NTRS1989

Viscous flow in simple curved gaps. I - An asymptotic theory. II - Viscous stress and shape function

The present asymptotic theory for generalized incompressible two-dimensional steady flow in curved channels has been constructed in the limit when gas thickness approaches zero with its lateral dimensions fixed; successive asymptotic solution terms are analytically generated by quadratures. In the second part of this work, the curvature of the gap treated is arbitrary. It is established that each term in the series solution of velocity and pressure is the product of a scale factor and a universal shape functions. Various interaction modes between the volume rate-of-flow, curvature, and its variations, are identified and quantitatively characterized.

Fan, D.-N.↗

NASA NTRS1982

Supersonic wing-body center of pressure with finite afterbodies

Closed-form formulas for the effects of finite afterbodies on the longitudinal center of pressure location in the presence of a wing at supersonic speeds are presented, along with solutions for the case of negative afterbodies. A double integral is developed for the case of subsonic and supersonic leading edges and no afterbody and full afterbody. Attention is also given to the full/infinite body case, noting that a proportional variation of the pitching moment with the lift is found.

Vira, N. R.↗

NASA NTRS1982

Closed-form solutions of supersonic wing-body interference

Closed-form formulas are presented for the interference factors of a body in the presence of a wing at supersonic speeds, when a finite afterbody is introduced. In addition, formulas are obtained for those cases in which the base of the body is forward of the trailing edge of the exposed root chord. These formulas are shown to be valid, subject to the restrictions inherent in the formulation given by Pitts, Nielsen and Kaattari (1959).

Vira, N. R.↗

NASA NTRS1977

Nonlinear stress waves in a perfectly flexible string

This paper discusses nonlinear stress-wave propagation in a perfectly flexible string obeying a quasilinear (rate-dependent) constitutive equation. Wave speeds and compatibility relations valid along various families of characteristics were determined. It was shown that the compatibility relations associated with the transverse as well as the longitudinal waves readily yield a physical interpretation when they are expressed in suitable variables and in vector form. Coding based on the present information was completed for the machine solution of a class of mixed initial- and boundary-value problems of practical interest. Computer simulation of the stress-wave interaction in the 40-foot lanyard in the Arcas 'Rocoz' system during deployment was carried out using a stress-strain relation for nylon at the strain rate of 30/second. A method for estimating the maximum tension and strain in a string during the initial loading phase is proposed.

Fan, D.-N.↗