Low Drag Aerofoils

1947 ◽  
Vol 51 (433) ◽  
pp. 54-64
Author(s):  
L. G. Whitehead
Keyword(s):  
Mach Number ◽  
Surface Finish ◽  
Experimental Work ◽  
Theoretical Basis ◽  
High Standard ◽  
Critical Value ◽  
Aircraft Wing ◽  
Critical Mach Number ◽  
The Past ◽  
Design And Manufacture

During the past few years a new series of low drag aerofoils has been developed which represents a radical departure from earlier practice. The changes envisaged are much greater than those which accompanied the general change-over from the biplane to the monoplane, and give rise to many problems whose solution requires considerable theoretical and experimental work. An important feature of the new sections is the precision in design and manufacture which is essential for their success. This has given renewed interest to the investigation of many of the detailed problems of air flow and calls for parallel improvements in manufacturing technique so as to achieve the high standard of surface finish required.The purpose of this paper is to give a brief account of the theoretical basis of the design and application of the modified profiles as aircraft wing sections. It deals with the design of aerofoils for the subsonic range only, or, to be more precise, for flight at speeds below the critical Mach Number at which shock waves are first formed. The critical value usually lies in the range 0.6 to 0.8, depending on the wing shape and incidence, as will be described in more detail later.

ABOUT CONSTRUCTION OF FLAT BODIES WITH INCREASED CRITICAL MACH NUMBER

2016 ◽  
Vol 47 (6) ◽  
pp. 563-579
Author(s):  
Sergey Alexandrovich Takovitskii
Keyword(s):  
Mach Number ◽  
Critical Mach Number

The J. C. Richardson Lecture: Prospects for Canadian Medical Neurology

1975 ◽  
Vol 2 (2) ◽  
pp. 101-107 ◽  
Author(s):  
D.W. Baxter
Keyword(s):  
Clinical Investigation ◽  
Postgraduate Education ◽  
High Standard ◽  
Undergraduate Curriculum ◽  
Influential Factors ◽  
Work Patterns ◽  
Consultation Service ◽  
The Past ◽  
Fundamental Research

In 1975, medical neurology is a well established, viable, growing specialty in Canada. There are now almost 250 neurologists scattered across the country, congregated largely in the hospitals associated with our 16 medical schools. Neurology is a major component of the undergraduate curriculum in each of these schools, and the majority of schools are approved for postgraduate training in our specialty. The Royal College has certified an average of 18 new neurologists each year for the past five years. In our hospitals we work closely with our internist and neurosurgical colleagues and we receive the support of highly competent teams of neuropathologists, clinical electrophysiologists and neuroradiologists. We believe that we provide a generally high standard of consultation service to our medical and surgical colleagues. We accept direct responsibility for patients suffering from a host of acute neurological problems, but we accept long term responsibility for very few. We do a great deal of teaching at both the undergraduate and graduate levels. In fact, the major role which neurology plays in undergraduate curricula, and the stimulus of postgraduate education, probably have been the two most influential factors shaping the number, work patterns and distribution of Canadian neurologists. Many of us are engaged in clinical investigation, but relatively few medical neurologists in Canada make fundamental research contributions.

Sensory Deprivation and Schizophrenia

1959 ◽  
Vol 105 (438) ◽  
pp. 235-237 ◽  
Author(s):  
A. Harris
Keyword(s):  
Experimental Work ◽  
Human Subjects ◽  
Sensory Deprivation ◽  
Sensory Stimulation ◽  
The Past ◽  
Therapeutic Procedures

Much interest has been displayed in the past few years in the effect on human subjects of reduction, or as far as possible, abolition of sensory stimulation, so that virtual isolation from the environment is produced. Recent comprehensive reviews have appeared, dealing with experimental work (Solomon et al. 1957) and conditions arising incidentally in the course of various therapeutic procedures (Grünthal 1957), and it is therefore unnecessary to deal with the topic at length here.

Dynamical theory of neutron diffraction

1978 ◽  
Vol 56 (10) ◽  
pp. 1261-1288 ◽  
Author(s):  
V. F. Sears
Keyword(s):  
Neutron Diffraction ◽  
Theoretical Basis ◽  
Dynamical Theory ◽  
Experimental Results ◽  
Neutron Interferometry ◽  
New Techniques ◽  
The Past ◽  
Neutron Optics ◽  
Coherent Wave ◽  
Special Cases

We present a review of the dynamical theory of neutron diffraction by macroscopic bodies which provides the theoretical basis for the study of neutron optics. We consider both the theory of dispersion, in which it is shown that the coherent wave in the medium satisfies a macroscopic one-body Schrödinger equation, and the theory of reflection, refraction, and diffraction in which the above equation is solved for a number of special cases of interest. The theory is illustrated with the help of experimental results obtained over the past 10 years by a number of new techniques such as neutron gravity refractometry, Pendellösung interference, and neutron interferometry.

Aeroelastic Problems in connection with High-Speed Flight

1956 ◽  
Vol 60 (547) ◽  
pp. 459-475 ◽  
Author(s):  
E. G. Broadbent
Keyword(s):  
Mach Number ◽  
High Speed ◽  
The Other ◽  
Control Surface ◽  
The Past ◽  
Other Hand ◽  
Aerodynamic Derivatives ◽  
Mach Numbers ◽  
The One

SummaryA review is given of developments in the field of aeroelasticity during the past ten years. The effect of steadily increasing Mach number has been two-fold: on the one hand the aerodynamic derivatives have changed, and in some cases brought new problems, and on the other hand the design for higher Mach numbers has led to thinner aerofoils and more slender fuselages for which the required stiffness is more difficult to provide. Both these aspects are discussed, and various methods of attack on the problems are considered. The relative merits of stiffness, damping and massbalance for the prevention of control surface flutter are discussed. A brief mention is made of the recent problems of damage from jet efflux and of the possible aeroelastic effects of kinetic heating.

scholarly journals Critical Mach Numbers of Flow around Two-Dimensional and Axisymmetric Bodies

Aerodynamics ◽  
2021 ◽  
Author(s):  
Vladimir Frolov
Keyword(s):  
Mach Number ◽  
Cross Section ◽  
Flow Simulation ◽  
The Body ◽  
Two Dimensional ◽  
Critical Mach Number ◽  
Method Of Integral Relations ◽  
Viscosity Factor ◽  
Mach Numbers ◽  
Axisymmetric Bodies

The paper presents the calculated results obtained by the author for critical Mach numbers of the flow around two-dimensional and axisymmetric bodies. Although the previously proposed method was applied by the author for two media, air and water, this chapter is devoted only to air. The main goal of the work is to show the high accuracy of the method. For this purpose, the work presents numerous comparisons with the data of other authors. This method showed acceptable accuracy in comparison with the Dorodnitsyn method of integral relations and other methods. In the method under consideration, the parameters of the compressible flow are calculated from the parameters of the flow of an incompressible fluid up to the Mach number of the incoming flow equal to the critical Mach number. This method does not depend on the means determination parameters of the incompressible flow. The calculation in software Flow Simulation was shown that the viscosity factor does not affect the value critical Mach number. It was found that with an increase in the relative thickness of the body, the value of the critical Mach number decreases. It was also found that the value of the critical Mach number for the two-dimensional case is always less than for the axisymmetric case for bodies with the same cross-section.

Characteristics of a co-flowing jet with varying lip thickness and constant bypass ratio

2019 ◽  
Vol 91 (9) ◽  
pp. 1205-1213 ◽  
Author(s):  
Naren Shankar R. ◽  
Kevin Bennett S.
Keyword(s):  
Design Methodology ◽  
Critical Value ◽  
Commercial Aircraft ◽  
Critical Limit ◽  
Potential Core ◽  
Content Type ◽  
Free Jet ◽  
The Past ◽  
Bypass Ratio ◽  
Practical Implications

Purpose Subsonic commercial aircraft operate with turbo-fan engines that operate with moderate bypass ratio (BR) co-flowing jets (CFJ). This study aims to analyse CFJ with constant BR 6.3 and varying primary nozzle lip thickness (LT) to find a critical LT in CFJ below which mixing enhances and beyond which mixing inhibits. Design/methodology/approach CFJ were characterized with a constant BR of 6.3 and varying lip thicknesses. A single free jet with a diameter equal to that of a primary nozzle of the co-flowing jet was also studied for comparison. Findings The results show that within a critical limit, the mixing enhanced with an increase in LT. This was signified by a reduction in potential core length (PCL). Beyond this limit, mixing inhibited leading to the elongation of PCL. This limit was controlled by parameters such as LT and magnitude of BR. Practical implications The BR value of CFJ in the present study was 6.3. This lies under the moderate BR value at which subsonic commercial turbofan operates. Hence, it becomes impervious to study its mixing behavior. Originality/value This is the first effort to find the critical value of LT for a constant BR for compressible co-flow jets. The CFJ with moderate BR and varying LT has not been studied in the past. The present study focuses on finding a critical LT below which mixing enhances and above which mixing inhibits.

Theories of Meaning in Schema Matching

2009 ◽  
pp. 282-308
Author(s):  
Joerg Evermann
Keyword(s):  
Theoretical Basis ◽  
Research Area ◽  
Schema Matching ◽  
Future Research ◽  
Database Integration ◽  
Ongoing Research ◽  
Matching Methods ◽  
The Past ◽  
Theories Of Meaning

Schema matching is the identification of database elements with similar meaning as preparation for subsequent database integration. Over the past 20 years, different schema-matching methods have been proposed and have been shown to be successful to various degrees. However, schema matching is an ongoing research area and the problem is not yet considered to be solved. This article reviews existing schema-matching methods from the perspective of theories of meanings drawn from philosophy and psychology. It positions existing methods, raises questions for future research based on these theories, and shows how these theories can form a firm theoretical basis as well as guide future schema-matching research.

Design of a continuous portable indraft supersonic wind tunnel

2020 ◽  
pp. 030641902090734
Author(s):  
Monty Bruckman II ◽  
Lance W Traub
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Sound Level ◽  
Wind Tunnels ◽  
Supersonic Wind Tunnel ◽  
Blow Down ◽  
Hands On ◽  
Compressible Fluid Flow ◽  
Aeronautical Engineering ◽  
Design And Manufacture

Programs in mechanical and aeronautical engineering commonly include courses in compressible fluid flow. As such, learning can be greatly enhanced if theory is taught in conjunction with hands on experimentation. While supersonic wind tunnels are not uncommon at many universities, such facilities are generally of the blow down configuration. Consequently, run time is very short and ear protection is required during operation, potentially hindering instruction. Furthermore, blow down configurations are typically expensive and large. This article presents the design and manufacture of a continuous, indraft, miniature supersonic wind tunnel. The tunnel was designed for a nominal test section Mach number of 2; validation indicated a Mach number of 1.96 was achieved. Vacuum was provided by a regenerative blower. The facility is portable and quiet; measurements indicated that the sound level around the tunnel when operational was less than 81 dB (compared to 119dB generated by the department’s blow down supersonic wind tunnel).

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