Recursos de colección
Caltech Authors (143.226 recursos)
Repository of works by Caltech published authors.
Group = Guggenheim Jet Propulsion Center
Repository of works by Caltech published authors.
Group = Guggenheim Jet Propulsion Center
Bohn, Mark S.
Some aspects of the noise generated internally by a turbojet engine are considered analytically and experimentally. The emphasis is placed on the interaction of pressure fluctuations and entropy fluctuations, produced by the combustion process in the engine, with gradients in the mean flow through the turbine blades or the exhaust nozzle. The results are directly applicable to the problem of excess noise in aircraft powerplants and suggest that the phenomenon described is the dominant mechanism. The one-dimensional interaction of pressure fluctuations and entropy fluctuations with a subsonic nozzle is solved analytically. The acoustic waves produced by each of three independent disturbances are investigated. These disturbances,...
Symington, William A.
A consistent set of continuum-like equations which describe, under certain limitations, the flow of bubbly gas-liquid mixtures is applied in the solution of a few problems that bear on technological issues of nuclear reactor safety. The solutions of these problems illustrate the significance of the ratio between the viscous relaxation time of the bubbles and the characteristic time of the flow, in scaling experimental results. The choked flow of a bubbly mixture through a contraction in a one-dimensional duct is treated. It is found that in many cases the ratio of the contraction residence time to the viscous relaxation time is small, indicating the...
Tsien, H. S.
An experimental and analytical investigation was undertaken to determine the influence of asymmetric inlet flows on the performance of axial turbomachinery. Overall performance measurements and circumferential surveys of total pressures, velocities and flow angles were obtained in an axial compressor with inlet disturbances covering approximately 25% of the inlet annulus area. Three configurations were tested to find the principal effects in a single rotor, a complete stage and a multi-stage machine. A two-dimensional linearized theory was developed which includes the effect of losses and leaving angle deviations in the blade rows. The analysis may also be applied to propagating stall so...
Dooley, Donald A.
The present analysis considers ignition and combustion in the laminar boundary layer of a constant temperature, semi-infinite flat plate. A one step unopposed "global" reaction following any order reaction kinetics with temperature dependence according to the Arrhenius rate law is assumed. For the case where the Prandtl and Schmidt numbers are equal, the determination of a similarity function relating the species concentrations to the local temperature greatly simplifies the analysis. The similarity function is shown to be equal to the dimensionless streamwise velocity when the Prandtl and Schmidt numbers are both equal to unity. A general analytic solution for the...
Penner, S. S.; Datner, P. P.
Kang, D. M.; Pinedo, C.; Culick, F. E. C.; Ratner, A.
Measurements of fuel mixture fraction are made for a jet flame in an acoustic chamber. Acoustic forcing creates a spatially-uniform, temporally-varying pressure field which results in oscillatory behavior in the flame . Forcing is at 22,27, 32, 37, and 55 Hz. To asses the oscillatory behavior, previous work included chemiluminescence, OH PUF, nitric oxide PUF imaging, and fuel mixture fraction measurements by infrared laser absorption. While these results illuminated what was happening to the flame chemistry, they did not provide a complete explanation as to why these things were happening. In this work, the fuel mixture fraction is measured through PUF...
Marble, Frank E.
Serdengecti, Sedat; Marble, Frank E.
The two-dimensional theory of airfoils with arbitrarily strong inlet flow into the upper surface was examined with the aim of developing a thin-airfoil theory which is valid for this condition. Such a theory has, in fact, been developed and reduces uniformly to the conventional thin-wing theory when the inlet flow vanishes. The integrals associated with the arbitrary shape, corresponding to the familiar Munk integrals, are somewhat more complex but not so as to make calculations difficult. To examine the limit for very high ratios of inlet to free-stream velocity, the theory of the Joukowski airfoil was extended to incorporate an arbitrary inlet on the upper surface. Because this calculation...
Wright, F. H.; Zukoski, E. E.
Flame stabilization and flame spreading are two processes of paramount importance in the design of combustion chambers. Sufficient experimental work has been carried out to make clear the mechanism of stabilization; however understanding of the process of flame spreading in a duct is still imperfect. This is perhaps not surprising because, in technically interesting cases, the spreading is turbulent and the behavior of even the simplest turbulent flame is still controversial. Furthermore, studies that have been made of flame spreading have been primarily directed at solving the practical problem of the determination of combustion efficiency rather than providing insight into the physical phenomena involved in the spreading process. The present investigation was undertaken to define the...
Puzyrewski, R.; Zukoski, E. E.
An experimental study was made of the disintegration of a liquid sheet due to gravity force. The influence of surface tension, viscosity, and density of liquids on the phenomenon of disintegration was found. Conditions of liquid sheet breaking into streams, as well as the frequency of appearance of streams and the mean diameter of droplets independent of properties of the liquid, were found experimentally.
Culick, F. E. C.
This paper summarizes work accomplished chiefly during the past five years on analysis of stability related to recent experimental results on combustion instabilities in dump combustors. The primary purpose is to provide the information in a form useful to those concerned with design and development of operational systems. Thus most substantial details are omitted and the material is presented in a qualitative fashion.
Penner, S. S.
Kerrebrock, Jack L.
Diffusion in vortex flows is considered as a simple case of the more general problem of diffusion in flows with large pressure gradients normal to the principal flow direction. Two examples are considered. In the first the two gases are assumed electrically neutral, and pressure and concentration diffusion are equally important. In the second, diffusion of the electrons of an ionized gas is studied. Diffusion due to electromagnetic body forces is of equal importance with pres sure diffusion in this case, while concentration diffusion is negligible. It is found in the first example that the ratio of the radial mass flow of...
Jacobs, T. A.
Budzinski, J. M.; Marble, F. E.; Zukoski, E. E.
A shock traveling in air interacts with a laminar jet of helium flowing normal to the direction of shock propagation. Planar laser Rayleigh scattering is used to study the deformation and motion of the originally circular jet cross-section. The velocity of the jet before the shock interaction is much less than the velocities generated by the shock wave. Thus, the helium jet serves to create a cylindrical bubble of a lighter density gas imbedded in a heavier one. Four different shock Mach numbers (1.066, 1.14, 1.5, and 2.0) are studied. Two different jet/air density ratios are examined by using pure helium in the jet in one case, and a mixture of airlhelium...
Penner, S. S.; Olfe, D. B.; Lapp, M.
Representative theoretical and experimental studies relating to the determination of gaseous radiation from isothermal systems are discussed. The following recently concluded studies are described: f-number measurements for OH behind shock fronts; a method for the direct determination of radiative and collisional life times of vibrationally excited, molecules; emissivity calculations for CO_2; emissivity calculations for a hydrogen plasma at temperatures up to about 10,000°K.
Penner, Stanford S.
Penner, S. S.; Williams, F.
FLAME stabilization is of importance in the practical design of ramjets and afterburners. It has been studied extensively in recent years, particularly with reference to bluff-body flame-holders. In the present survey we describe the investigations relating to flame holding by bluff bodies as well as new techniques (e.g.,. flame holding by the use of reverse jets) which may prove to be of practical importance in new engine configurations. In Section II we consider the flow field downstream of a bluff-body flame-holder which includes the recirculation zone behind the body and a region of flame spreading farther downstream. Explicit reference is made to crucial experiments which...
Zukoski, Edward E.
The purpose of this paper is to describe briefly and in a general way several schemes used to calculate the motion of smoke through a structure or part of a structure involved in a fire. Calculations of this type are required if we are to understand the spread fire through the structure and if we are to learn how to write building codes and other regulations which can provide the best possible protection for building occupants. For example, one of aims of designers of high rise buildings is the incorporation in their designs of regions where people can be protected...