The absence of combustion engine noise pushes increasingly attention to the sound generation from other, even much weaker, sources in the acoustic design of electric vehicles. The present work focusses on the numerical computation of flow induced noise, typically emerging in components of flow guiding devices in electro-mobile applications. The method of Large-Eddy Simulation (LES) represents a powerful technique for capturing most part of the turbulent fluctuating motion, which qualifies this approach as a highly reliable candidate for providing a sufficiently accurate level of description of the flow induced generation of sound.
Over the past decade, there have been many efforts to generate engine sound inside the cabin either in reducing way or in enhancing way. To reduce the engine noise, the passive way, such as sound absorption or sound insulation, was widely used but it has a limitation on its reduction performance. In recent days, with the development of signal processing technology, ANC (Active Noise Control) is been used to reduce the engine noise inside the cabin. On the other hand, technologies such as ASD (Active Sound Design) and ESG (Engine Sound Generator) have been used to generate the engine sound inside the vehicle. In the last ISNVH, Hyundai Motor Company newly introduced ESEV (Engine Sound by Engine Vibration) technology. This paper describes the ESEV Plus Minus that uses engine vibration to not only enhance the certain engine order components but reduce the other components at the same time. Consequently, this technology would produce a much more diverse engine sound.
The acoustic trim components play an essential role in Noise, Vibration and Harshness (NVH) behavior by reducing both the structure borne and airborne noise transmission while participating to the absorption inside the car and the damping of the structure. Over the past years, the interest for numerical solutions to predict the noise including trim effects in mid frequency range has grown, leading to the development of dedicated CAE tools. Finite Element (FE) models are an established method to analyze NVH problems. FE analysis is a robust and versatile approach that can be used for a large number of applications, like noise prediction inside and outside the vehicle due to different sources or pass-by noise simulation. Typically, results feature high quality correlations. However, future challenges, such as electric motorized vehicles, with changes of the motor noise spectrum, will require an extension of the existing approaches.
BEGINNING with a statement of the requirements of a high-temperature cooling-liquid and a short history of what had been previously done in this field, the author gives a description of the liquid used in the investigation which was conducted by the Materiel Division at Wright Field. The investigation is divided into five parts which includes dynamometer test of Curtiss V-1570 and D-12 engines, endurance test and flight tests of D-12 engine and a dynamometer test of a high compression-ratio D-12 engine. The engines and cooling systems used, the results obtained and troubles experienced are given in detail, with curves, sketches and views of the airplanes. Extremely low fuel-consumption was obtained, and the results show that the ratio of installed weight to power of a liquid-cooled airplane-engine is considerably reduced by using this system of cooling.
AFTER defining the meaning of store-door delivery and outlining its history in Canada, the author reviews in detail the functions of the cartage agent and the railroad company under that system, and gives an idea of the territory and population served. Operation of Canadian store-door delivery is fully described, both as to the terminal facilities and the methods of handling, recording and checking outbound and inbound freight shipments. The author shows that in eastern Canada more than 97 per cent of the carted inbound tonnage is delivered to consignees by the end of the day following its receipt at the railroad sheds. Cartage tariffs used in Canadian store-door delivery are given and the legal situation involved in the operation of cartage service by railroads is outlined.
“DON'T let any industry kid itself that it is not in the midst of an absolute change, and particularly if it be a transportation industry. “This will not be a mere slight improvement or an addition of attachments and gadgets, but an absolute fundamental metamorphosis. “Industry, after its bristling period in the market, went into a coma and disappeared entirely into the chrysalis of the experimental laboratory where it has been for four years. Now, under the impetus of the new day, it is emerging from this cocoon of experimentation no longer a narrow short-sighted, crawling creature, but a butterfly with wings, preening itself in the sun and ready to take off almost any time for far more distant flights of progress than ever before in the history of mankind.” Mr.
THIS paper contains a brief description of the history, theory and application of photoelasticity, which is a new and useful optical method of stress analysis. A simple, cheap and compact photoelastic polariscope developed for the purpose is described. The application of photoelasticity to indeterminate truss-stress analysis produces quantitative stress measurements within a maximum experimental error of 6 per cent. The tests yield with considerable speed and convenience information concerning stress concentrations at corners and fillets that cannot be obtained by other methods. The author describes a photoelastic test of an airplane-wing-rib model whereby the axial and bending stresses in the members are determined and severe stress concentrations at the spar corners are noted.
EXISTING legal restrictions prevent the public from deriving the utmost benefits from the progress made in transport-vehicle and highway engineering. Legislative regulation has not yet affected the design of passenger automobiles in this Country, but curtailment of usage is evident in those States where gasoline taxes have reached exorbitant levels. The design and operation of motorcoaches, trucks and trailers has been affected, and the trend of motor-vehicle legislation presents a problem that is more acute than ever before in the history of the industry. We have 49 different sets of State and District regulations, each differing in some ways from the others, most seriously as regards size and weight. If uniform regulations could be put into effect in all States, design and operating practices would be simplified and lower manufacturing and operating costs effected.
THE purpose of this paper is to pass on to airplane designers the things that have been learned in the last year about flutter and vibration of structures to which control surfaces are attached in order that, benefiting by all experience available, this great source of danger in new designs may be controlled. Test pilots also should be interested in this subject because it may help them in deciding proper action when a case of flutter is encountered and to recognize vibrations which may lead to destructive flutter. The present-day methods of stress analyses, imperfect though they are in certain respects, and the design load-factors in current use are adequate to provide all the strength needed in airplane structures for flight in rough air, and for all necessary maneuvers. A review of structural failures in the air reveals the fact that a resonant vibration was in nearly all cases responsible.
MUCH study has been given by the author to the history and development of the pneumatic tire in preparation for the writing of this paper. He found in THE JOURNAL of the Society a great wealth of detailed information in papers extending back to 1913 and gives a comprehensive and interesting review of the earliest patent, taken out in England in 1845, and later patents on fundamental ideas. Successive improvements are described, progressively increased section size and reduced inflation-pressures are set forth, truck and motorcoach tire developments and trends are discussed at length and new types of tire that have made their advent in the last two years are described and illustrated. Among these new tires are the airplane and passenger-car airwheel or super-balloon, the lug-type pneumatic for industrial tractors and road-building machines, the startling development of the airwheel or super-balloon for farm tractors and the pneumatic tire for rail-cars.
AN investigation of the accelerated oxidation method for predicting the gum stability of gasolines was made to determine the effects of oxygen pressure and of temperature on the observed induction periods. The data obtained on the effect of pressure indicated that there was a definite relation between the induction period at any pressure and the induction period at an air pressure of 1 atmosphere. The data obtained on the effect of temperature showed that the induction periods of different gasolines changed to a different extent with temperature, so that gasolines with the same induction period at any one temperature might have very different periods of stability at storage temperatures. Since temperature has a marked effect on the observed induction period and since the gasoline is at a lower temperature than that of the bath for a considerable period of time at the beginning of the experiment, a correction factor was applied to obtain true induction periods at the bath temperature.
THE TRACTIVE ability of a motor-vehicle, as stated by the author, is the measure of its power to overcome outside resistances to its translation, based on the tangential force exerted by the driving wheels at their points of contact with the road. The propelling force is derived from the engine. To compute the “tangential force” of the foregoing definition it is engine torque that interests us rather than the horsepower, he states. If the horsepower is given, it can be converted into torque. After analyzing this point mathematically, the author discusses typical tractive-factors of modern motor-trucks so that he is enabled to develop an economic factor mathematically and thus be prepared to discuss tractive resistance as opposed to tractive effort. Air resistance is considered in detail as a particularly important factor concerning motorcoaches, and the author's points are backed up by diagrams and charts as well as by numerous tables of statistical and computed data.
After indicating the line of development since November, 1918, toward making the internal-combustion engine better adapted to aircraft service, the successful application of the supercharger to improve engine performance at great altitude is described and the over-dimensioned and over-compressioned engine also is discussed as a means toward that end. The use of anti-knock compounds to permit the use of high compression-ratios at small altitudes without knocking is commented upon and engine size is considered for both airplane and dirigible service. Further review includes air-cooling experiments in reference to the air-cooled radial engine, refinement of aviation-engine details, and improvements in aircraft powerplant parts and fuel-supply systems. For commercial aviation, powerplant reliability and low cost are stated as essentials. Illustrations are presented of the supercharger and of the engines and sylphon fuel-pump mentioned.
Dr. Dickinson outlines the history of the Research Department since its organization, indicates why the universities are the principal bases of operation for pure research, describes how the department functions as a clearing-house with regard to research data and comments upon the bright prospects for the future. He enumerates also the facilities the Research Department has for the coordination of research problems. The practical achievements of the Department have resulted from its recent concentration upon the three major projects of study with regard to the tractive resistance of roads, with reference to fuel and to testing programs, and of an effort to render financial assistance to the Bureau of Standards and the Bureau of Mines that would enable these Bureaus to continue their elaborate research programs, details of all of this work being included.
The author (Chicago Tractor Meeting paper) divides the history of the application of mechanical power to farm work into three periods, reviews each one and comments upon the various phases of progressive development that influence the type of tractor most desirable for satisfying present needs. The requirements of farm work are outlined, and the different types of tractor built and being constructed to meet these demands are reviewed, discussion of large versus small tractors, type of drive, power needed, control, methods of operation and the factors constituting general-purpose service being included. So far as adopting the tractor for farm usage is concerned, the author believes that the present limitation of such utilization lies with the tractor industry and with tractor engineers, rather than with the farmer.
Transportation by motorbus, although of recent origin, has advanced rapidly in its development but is still undergoing a process of evolution. Less than 10 years ago, motor carriers were mostly “jitneys” and were heartily disliked by electric-railway officials. Now, motorbuses are developing a field of their own and are rendering a service not supplied by any other transportation agency, two of their most valuable functions being the building up of new territory and acting as feeders to established lines in the more thickly settled areas. The first steps in their development took place while engaged in local service, but the trend toward interurban business soon became manifest. In California, within the last 10 years, the interurban business has increased from that of a few isolated individuals to the operating of approximately 1000 vehicles, which cover the entire State and, in 1923, carried about 25,000,000 passengers.
First sketching the history of the sleeve-valve engine, the author reviews the valve action of the Knight, discusses combustion-chamber shape and comments upon permissible compression, remarking also on the subject of carbon deposit in the sleeve-valve type of engine. Endurance tests of Knight engines are described and, in the author's opinion, should constitute a reliable guide in judging its performance characteristics. From the beginning, one of the foremost claims for the sleeve-valve engine has been that the sleeve type of valve permits much greater port openings and more rapid opening and closing of the ports. In view of this claim, it is said to be rather strange that sleeve-valve engines have not been more of a factor in speed contests; but the explanation undoubtedly is that exceedingly large valve-capacity can be obtained with poppet valves if quiet valve-action is not a consideration, according to the author.
The author gives a brief review of developments during the past year in the construction of aeroplanes, particularly as affected by the European War. He takes as an example the Renault twelve-cylinder engine, citing the respects in which the present differs from previous models. Such factors as the changes in cooling systems, method of drive, valve construction and starting devices are considered. The requirements of aeroplane engines, such as constant service, high speeds (of aeroplanes) and stream-line form of engines and radiators, are outlined. Propeller requirements are dealt with at length, curves being given by which the efficiency and diameter of the propeller can be obtained. In conclusion a number of different engine installations are illustrated and compared.