Latest content added for UNT Digital Library Collection: National Advisory Committee for Aeronautics (NACA)http://digital.library.unt.edu/explore/collections/NACA/browse/?sort=added_d&fq=untl_decade:1940-19492015-02-26T16:50:55-06:00UNT LibrariesThis is a custom feed for browsing UNT Digital Library Collection: National Advisory Committee for Aeronautics (NACA)Some Recent Contributions to the Study of Transition and Turbulent Boundary Layers2015-02-26T16:50:55-06:00http://digital.library.unt.edu/ark:/67531/metadc172454/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc172454/"><img alt="Some Recent Contributions to the Study of Transition and Turbulent Boundary Layers" title="Some Recent Contributions to the Study of Transition and Turbulent Boundary Layers" src="http://digital.library.unt.edu/ark:/67531/metadc172454/thumbnail/"/></a></p><p>None</p>Considerations of the Total Drag of Supersonic Airfoil Sections2015-02-26T16:50:55-06:00http://digital.library.unt.edu/ark:/67531/metadc172466/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc172466/"><img alt="Considerations of the Total Drag of Supersonic Airfoil Sections" title="Considerations of the Total Drag of Supersonic Airfoil Sections" src="http://digital.library.unt.edu/ark:/67531/metadc172466/thumbnail/"/></a></p><p>The results of calculations of the viscous and pressure drags of some two-dimensional supersonic airfoils at zero lift are presented. The results indicate that inclusion of viscous drag alters many previous results regarding the desirability of certain airfoil shapes for securing low drags at supersonic speeds. At certain Reynolds and Mach numbers, for instance, a circular-arc airfoil may theoretically have less drag than the previously advocated symmetrical wedge-shape profile; although under different conditions, the circular-arc airfoil may have a higher drag.</p>Two-Dimensional Irrotational Transonic Flows of a Compressible Fluid2014-09-25T20:32:43-05:00http://digital.library.unt.edu/ark:/67531/metadc172480/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc172480/"><img alt="Two-Dimensional Irrotational Transonic Flows of a Compressible Fluid" title="Two-Dimensional Irrotational Transonic Flows of a Compressible Fluid" src="http://digital.library.unt.edu/ark:/67531/metadc172480/thumbnail/"/></a></p><p>The methods of NACA TN No. 995 have been slightly modified and extended in include flows with circulation by considering the alteration of the singularities of the incompressible solution due to the presence of the hypergeometric functions in the analytic continuation of the solution. It was found that for finite Mach numbers the only case in which the nature of the singularity can remain unchanged is for a ratio of specific heats equal to -1. From a study of two particular flows it seems that the effect of geometry cannot be neglected, and the conventional "pressure-correction" formulas are not valid, even in the subsonic region if the body is thick, especially if there is a supersonic region in the flow.</p>Tables and Charts of Flow Parameters Across Oblique Shocks2014-09-25T20:32:43-05:00http://digital.library.unt.edu/ark:/67531/metadc172508/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc172508/"><img alt="Tables and Charts of Flow Parameters Across Oblique Shocks" title="Tables and Charts of Flow Parameters Across Oblique Shocks" src="http://digital.library.unt.edu/ark:/67531/metadc172508/thumbnail/"/></a></p><p>Shock-wave equations have been evaluated for a range of Mach number in front of the shock from 1.05 to 4.0. Mach number behind the shock, pressure ratio, derivation of flow, and angle of shock are presented on charts. Values are also included for density ratio and change in entropy.</p>Charts for the Computation of Equilibrium Composition of Chemical Reactions in the Carbon-Hydrogen-Nitrogen System at Temperatures from 2000 to 5000 Degrees K2014-09-25T20:32:43-05:00http://digital.library.unt.edu/ark:/67531/metadc100821/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc100821/"><img alt="Charts for the Computation of Equilibrium Composition of Chemical Reactions in the Carbon-Hydrogen-Nitrogen System at Temperatures from 2000 to 5000 Degrees K" title="Charts for the Computation of Equilibrium Composition of Chemical Reactions in the Carbon-Hydrogen-Nitrogen System at Temperatures from 2000 to 5000 Degrees K" src="http://digital.library.unt.edu/ark:/67531/metadc100821/thumbnail/"/></a></p><p>Charts are provided for the estimation and progressive adjustment of two independent variables on which the calculations are based. Additional charts are provided for the graphical calculation of the composition.</p>An investigation of aircraft heaters IX : measured and predicted performance of two exhaust gas-air heat exchangers and an apparatus for evaluating exhaust gas-air heat exchangers2014-03-30T18:00:15-05:00http://digital.library.unt.edu/ark:/67531/metadc279620/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc279620/"><img alt="An investigation of aircraft heaters IX : measured and predicted performance of two exhaust gas-air heat exchangers and an apparatus for evaluating exhaust gas-air heat exchangers" title="An investigation of aircraft heaters IX : measured and predicted performance of two exhaust gas-air heat exchangers and an apparatus for evaluating exhaust gas-air heat exchangers" src="http://digital.library.unt.edu/ark:/67531/metadc279620/thumbnail/"/></a></p><p>None</p>The Lagrangian Multiplier Method of Finding Upper and Lower Limits to Critical Stresses of Clamped Plates2014-03-30T18:00:15-05:00http://digital.library.unt.edu/ark:/67531/metadc279603/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc279603/"><img alt="The Lagrangian Multiplier Method of Finding Upper and Lower Limits to Critical Stresses of Clamped Plates" title="The Lagrangian Multiplier Method of Finding Upper and Lower Limits to Critical Stresses of Clamped Plates" src="http://digital.library.unt.edu/ark:/67531/metadc279603/thumbnail/"/></a></p><p>The theory of Lagrangian multipliers is applied to the problem of finding both upper and lower limits to the true compressive buckling stress of a clamped rectangular plate. The upper and lower limits thus bracket the truss, which cannot be exactly found by the differential-equation approach. The procedure for obtaining the upper limit, which is believed to be new, presents certain advantages over the classical Raleigh-Rite method of finding upper limits. The theory of the lower-limit procedure has been given by Trefftz but, in the present application, the method differs from that of Trefftz in a way that makes it inherently more quickly convergent. It is expected that in other buckling problems and in some vibration problems problems the Lagrangian multiplier method finding upper and lower limits may be advantageously applied to the calculation of buckling stresses and natural frequencies.</p>A Concise Theoretical Method for Profile-Drag Calculation; Advance Report2014-03-30T18:00:15-05:00http://digital.library.unt.edu/ark:/67531/metadc279600/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc279600/"><img alt="A Concise Theoretical Method for Profile-Drag Calculation; Advance Report" title="A Concise Theoretical Method for Profile-Drag Calculation; Advance Report" src="http://digital.library.unt.edu/ark:/67531/metadc279600/thumbnail/"/></a></p><p>In this report a method is presented for the calculation of the profile drag of airfoil sections. The method requlres only a knowledge of the theoretical velocity distribution and can be applied readily once this dlstribution is ascertained. Comparison of calculated and experimental drag characteristics for several airfoils shows a satisfactory agreement. Sample calculatlons are included.</p>Spin tests of two models of a low-wing monoplane to investigate scale effect in the model test range2014-03-30T18:00:15-05:00http://digital.library.unt.edu/ark:/67531/metadc279675/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc279675/"><img alt="Spin tests of two models of a low-wing monoplane to investigate scale effect in the model test range" title="Spin tests of two models of a low-wing monoplane to investigate scale effect in the model test range" src="http://digital.library.unt.edu/ark:/67531/metadc279675/thumbnail/"/></a></p><p>None</p>Analysis of heat and compressibility effects in internal flow systems and high-speed tests of a ram-jet system2014-03-30T18:00:15-05:00http://digital.library.unt.edu/ark:/67531/metadc279610/<p><a href="http://digital.library.unt.edu/ark:/67531/metadc279610/"><img alt="Analysis of heat and compressibility effects in internal flow systems and high-speed tests of a ram-jet system" title="Analysis of heat and compressibility effects in internal flow systems and high-speed tests of a ram-jet system" src="http://digital.library.unt.edu/ark:/67531/metadc279610/thumbnail/"/></a></p><p>None</p>