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Viewing 7621 to 7650 of 7768
1959-01-01
Technical Paper
590006
Guy J. Sanders
WITH the advent of low-pressure tires and the success of car noise reduction efforts by automotive engineers, tire thump has become a more noticeable problem. This paper discusses some recent research in this area.* A tire's susceptibility to thump can be predicted from the difference frequency between diametrical and circular modes of vibration. The author describes the testing and procedure uses to find the source of thump. The way to minimize thump is to shape and construct the tire so that it does not permit coincidence of two natural frequencies with two revolution rate harmonics in the 20–35 mph speed range.
1959-01-01
Technical Paper
590082
R. R. Regelbrugge
1959-01-01
Technical Paper
590142
JOHN M. TYLER, THOMAS G. SOFRIN, JACK W. DAVIS
1959-01-01
Technical Paper
590127
A. E. W. AUSTEN, T. PRIEDE
Summary The effect of engine speed load and size (swept volume) on noise has been evaluated on a limited range of engines. Total sound intensity (but omitting low frequency components due to air intake noise) varies as (speed)3, as (swept volume) and very little with load. The noise from a petrol engine was of the same order of magnitude as that of the diesel engines at full load but considerably less at low load. The following sources of noise have been identified and means of reducing them adequately established in principle. Narrow band frequency analysis has been shown to be a convenient criterion of the “noisiness” of the form of the cylinder pressure and in conjunction with noise measurement makes it possible to evaluate separately the noisiness of the engine structure. In the small diesel engines tested in this respect, it should be possible to quieten some (by about 5 db in the critical frequency range) by smoothing the cylinder-pressure-rise.
1959-01-01
Technical Paper
590019
R. H. Perry, H. V. Lowther
ENGINE noise has become an increasing problem with the higher and higher compression ratios of present-day automotive engines. Because fuel octane number cannot be raised indefinitely, the problem is one of engine design and selection of crankcase lubricating oils and gasoline formulations, the authors think. This paper describes investigations into the cause of spark knock, wild ping, rumble, and the added problem of hot-spot surface ignition (which also intensifies as compression ratios increase). The authors have found gasolines with phosphorous additives, used with properly formulated multiviscosity lubricating oils, provide a partial answer to the problem of engine rumble. The authors conclude that very exact tailoring of fuels, lubricants, additives, and engines will be necessary to prevent engine noise if compression ratios continue to rise.
1959-01-01
Technical Paper
590007
K. P. Pettibone
1959-01-01
Technical Paper
590052
Fred Mintz
THIS PAPER outlines progress to October, 1958, on the new Shock and Vibration Manual. At that point, the methods of solving vibration isolation problems had been established. After further refinements and expansion, the manual will be issued by SAE Committee S-12 on Shock and Vibration. The manual will set up procedures to be followed by engineers who don't have extensive experience in the field. It will give procedures for problems having up to six degrees of freedom. The procedure, as described in the paper, now consists of three steps: 1. Specification of the data required for the solution of a given problem. 2. Calculating whether vibration isolators are needed. 3. Determining the dynamic properties of the isolation system when the above step indicates isolation mounts are needed.
1959-01-01
Technical Paper
590398
JOHN O. ANDERSON, C. HAROLD EK, CHARLES W. GADD
1958-01-01
Technical Paper
580064
J. C. Livengood, C. F. Taylor, P. C. Wu
THIS paper outlines a new method of measuring end-gas temperatures within the cylinder of an operating engine. The new instrument measures the acoustical properties by the pulse method, transmitting an acoustical impulse through a gas path of known length and measuring the time of propagation through the gas. The method yields a value for the average velocity of sound in the path. The authors describe the instrument and engine modifications necessary. The results of tests are also discussed, with a detailed description of one series. The appendixes outline the mathematical steps of finding the sound velocity in gas mixtures and the fuel-air cycle for the detailed series of tests.
1958-01-01
Technical Paper
580249
C. N. FANGMAN, J. L. HOFFMAN
1958-01-01
Technical Paper
580275
CARL L. DELLINGER
1958-01-01
Technical Paper
580379
G. W. PAINTER
1958-01-01
Technical Paper
580334
V. F. Massa
Problems in combustion at low engine speeds have been created by the high levels of compression ratio in current U. S. passenger cars. These are: Hot starting noise, hot cranking difficulty and after-running. These combustion irregularities are not major field problems at present, but their severity and frequency of occurrence will probably increase as compression ratio continues to rise. An investigation of these low speed combustion irregularities has been conducted in the laboratory and on the road. It has been found that hot starting noise usually occurs during the first revolution the engine makes when being cranked. Although starting noise may result from compression ignition, it usually follows spark ignition. It can be influenced by engine operating conditions, compression ratio level, engine water jacket temperature, cranking speed and fuel type. The starting noise behavior of a fuel has been related to its octane quality, volatility, and aromaticity.
1958-01-01
Technical Paper
580345
K. A. BEIER, T. J. WEIR
1958-01-01
Technical Paper
580054
A. O. Sykes
THE effects on the transmission of vibration through isolation mounts of machine and foundation resilience, and of wave propagation are investigated. The prediction of the effectiveness of mounts is discussed, and curves are presented for estimating their effectiveness under certain conditions. A number of conclusions are drawn relevant to the problems of mount design and selection.
1958-01-01
Technical Paper
580252
R. H. BOLLINGER, H. N. McGREGOR
1958-01-01
Technical Paper
580342
T. A. ROBERTSON, J. H. COX
1958-01-01
Technical Paper
580343
DEAN G. THOMAS
1958-01-01
Technical Paper
580052
L. M. Ball
THIS paper explains a few of the basic principles of the character of sound and the mechanism of human hearing. The author describes some simple experiments which demonstrate the relationship between intensity and loudness and the nature of harmony. He also points out the difficulties of accurately analyzing sound electronically, and the resulting importance of combining the finest electronic equipment with sharp, attentive human faculties. Five basic ways to reduce noise and the mechanics of each are described. The effect of these methods on the work of the sound engineer is indicated.
1957-01-01
Technical Paper
570139
ROBERT S. BRADFORD
1957-01-01
Technical Paper
570049
M. M. Miller
BEFORE an evaluation of suppressors can be made or before a sensible discussion of suppression goals can be carried on, terms, conditions, and possibilities must be understood. A five-number system for evaluating suppressors is proposed. Methods of jet noise suppression undergoing general development today include frequency shifting, jet spreading, and jet velocity reduction. Basic types of jet spreaders and velocity reducers are shown and ratings given. Combinations of types have resulted in increased suppression in many instances.
1957-01-01
Technical Paper
570324
K. A. BEIER
1957-01-01
Technical Paper
570030
J. A. Joyner
THIS paper deals with cavitation pitting where vacuum bubbles exist. Experiments are described which attempt to correct this condition where plating of liners varied in composition and thickness. It was concluded that a nickel-chrome plating has very good resistance to cavitation-pitting attack. Investigation of cylinder-wall vibration was made to find out about the cause of cavitation. Minimum liner wall vibration results with use of a 2-piece heavy wall liner and a piston with 20% less clearance. Endurance tests prove that on these pitting has been eliminated.
1957-01-01
Technical Paper
570025
N. D. Sanders, F. C. Laurence
EQUATIONS relating to noise outside a turbulent jet to the turbulent velocities inside the jet have been derived making use of Lighthill's suggestion that the actual flow field can be simulated with a stationary field of quadrupoles. Hot-wire anemometer techniques were applied to a 3V½-in. air jet to measure the turbulent structure of the mixing region. These measurements and the previously derived equations were used to estimate some of the characteristics of the sound field. The estimated characteristics were found to be in good agreement with the experimentally measured sound field of a full-scale turbojet engine.
1957-01-01
Technical Paper
570326
W.A. BONVALLET
1957-01-01
Technical Paper
570227
G. J. ENGELHARD
1957-01-01
Technical Paper
570287
L. E. MULLER, ELMER GREENE
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