bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent Developments in the Nsu Wankel Engine
Authors: Froede W. 
Published: June 2010

Eight years have passed since the first rotary engine system NSU Wankel showed positive torque on the test bench at Neckarsulm. At present four different types are in production, although the production rate is still comparatively low. Sixteen companies in Europe, America and Asia are pushing the development whereby a close and friendly co-operation is assisting progress. This paper deals only with the development done at NSU Motorenwerke, Neckarsulm, as naturally the other licencees do not want to disclose their plans before they have reached a final stage. It may be remembered that the size of the rotary engines under development covers a wide range between 3 and 800 h.p. Furthermore, a wide field of applications is visualized, covering lawn-mower engines, chain-saw units, automotive engines, stationary engines for all kinds of purposes and boat drives. The most attractive type, from a production viewpoint, is the automotive engine which at the same time presents the most technical difficulties. This type of engine requires not only low production cost but high durability and a lot of specific features such as regular idling, high torque at low speed, smooth operation within the complete load and power field and cold starting possibility. NSU has concentrated development activities on two different systems of rotary engines, namely a series of air-cooled engines and two types of water-cooled units which are identical in their main components.
Second Paper: Some Aspects of the Design and Operation of the Three-Wheeled Road Roller
Authors: Wass F. H. 
Published: June 2010

Following an introduction of general historic nature dealing with the evolution of the modern road roller from the first practicable steam roller of 100 years ago, the paper is confined generally to an examination of the mechanical engineering content and operational requirements of this item of engineering plant universally employed in today's surface consolidation, compaction and finishing processes. The mechanical constitution of the road roller is examined with particular reference to recent developments in design concerning clutches, mechanical, hydrokinetic and hydrostatic transmissions, steering, brakes, bearings and hydraulic systems, all of which are in close accord with modern automotive design practice. Curves illustrate the basic co-ordination requirements of engine/torque converter combination, the torque converter and hydrostatic unit output performance characteristics and vehicle road performance (gradient/ mile/h) with the mechanical ‘stepped’ transmission, the overlapping torque converter transmission and infinite ratio ‘stepless’ hydrostatic system. Additional equipment fitted to the roller for performing operations other than surface rolling is also considered together with features designed to produce maximum operational efficiency. Modern design trends to satisfy present-day demands of maximum machine utilization with minimum servicing and maintenance ‘down-times’ are considered with particular reference to lubrication and accessibility for servicing. Conclusions to past and present are given in the author's views on probable future trends in design and construction.
The Influence of Engine Design on Spark Knock at Low Engine Speeds
Authors: Marshall By E. L. 
Published: June 2010

Although spark knock at low engine speeds is unlikely to cause engine damage it is unacceptable to the car driver and must therefore be avoided. The degree of, or freedom from, knock may be influenced by both gasoline formulation and engine design. An analysis of the octane requirements of some 30 European manual transmission car models revealed that, apart from compression ratio and ignition advance, the features of engine design which affect low speed antiknock requirements significantly are mixture velocity through the carburettor and the type of intake manifold heating employed. When considering mass produced engines of modern multi-cylinder design, factors such as cylinder head, combustion chamber and camshaft design have little influence upon engine anti-knock requirements under low speed, accelerating, conditions. To achieve optimum utilization of currently available gasoline quality, the calculated mean mixture velocity should be at least 75 ft/s through the carburettor venturi and 45 ft/s through the carburettor barrel. That such conditions are already employed in some designs is proof of their practicability.
Problems Associated with the Use of Skirts on Hovercraft
Authors: Crago W. A. 
Published: June 2010

The lecture commences with a brief description of early hovercraft work and shows how the advent of flexible extensions to the peripheral jets—or ‘skirts’—constituted a breakthrough without which the hovercraft would never have become a practical proposition with the ability to operate over waves and rough ground. It is shown that the introduction of skirts, whilst providing a solution in one respect, also led to a series of problems and three of these are singled out for further discussion. First it is shown that whilst a relatively high internal skirt pressure is desirable to maintain skirt shape under operational conditions, this pressure can also lead to a high rough water drag. The second problem is that of ‘plough in’ and overturning, which is intimately associated with the use of skins. The hydrodynamic mechanisms of both these undesirable phenomena are for the first time explained in detail and are illustrated by means of data obtained from two- and three-dimensional model tests. The third problem raised by the introduction of skirts is skirt oscillation and wear. The techniques necessary to investigate delamination are described and some of the factors which have been shown to be important in increasing delamination life are outlined.
An Investigation into the Dynamic Stability of Steering Systems
Authors: Barre R. P. La , Mills B. 
Published: June 2010

The historical background of the automobile shimmy problem is outlined. The behaviour of a suspension and steering system is predicted using a one-term harmonic approximation to the solution of the simplified equations of motion of the system. These equations include the effects of the nonlinear variation of the tyre aligning torque with applied slip angle and of the relaxation properties of the tyre. The unstable frequency regions of the steering system are predicted with and without coupling of the steering and vertical suspension motions. An estimate of the level of damping required to suppress the shimmy motion is made. An apparatus for the determination of the relevant tyre properties is described. The experimental results obtained for the behaviour of a laboratory suspension unit are compared with those predicted theoretically and the agreement is found to be reasonable.
The Vertical Response Characteristics of the Non-Rolling Tyre
Authors: Overton J. A. , Mills B. , Ashley C. 
Published: June 2010

Due to the complexity of the dynamic behaviour of the pneumatic tyre a preliminary study is carried out to determine experimentally the vertical response characteristics of the non-rolling tyre. This approach is further justified because of the general use of the laboratory road simulator in which the excitation is through a non-rolling tyre. A measurement technique based on the concept of mobility is used to show that the tyre exhibits a fundamental rigid body mode as well as higher tread flexural modes of vibration. Comparisons are then made between the behaviour of a cross-ply and a radial-ply tyre over a range of pressure levels. The results show that there are marked differences between the two types both in the character of the response and the level of damping. The commonly used mathematical model to represent the fundamental mode is shown to be inadequate. A viscoelastic model is proposed, to describe this mode of vibration, which includes frequency-dependent stiffness and damping coefficients. The theory is further developed to predict motion transmissibility across the tyre from the input mobility data.
The Nature and Prevention of Axle Tramp
Authors: Sharp R. S. 
Published: June 2010

An analogue computer simulation of vibrations occurring with automobile rear axles under braking and accelerating conditions, commonly called “axle tramp’ is described. These vibrations are shown to be self-excited, and the existence of limit cycles is demonstrated. The mode shapes corresponding to these limit cycles are described, and the mechanisms through which the self-excitation is possible are deduced. The ways in which the stability of the system and the limit cycles are affected by changes in the system design are indicated, and the longitudinal axle mounting stiffness is identified as a critical parameter, having a major influence on the stability. It is concluded that axle tramp can be eliminated by suitable attention to the design of the axle to body mounting.
Steering Mechanisms
Authors: Bastow D 
Published: June 2010

It is considered that this survey will be most useful if it is concerned with the principles employed and some typical methods of applying them rather than attempting to provide a comprehensive catalogue of all the component parts of steering mechanisms, especially as at least some history may be interesting. For instance, rocker shaft type boxes, which were originally practically universal, so long as they were concerned with front axles had to play their part in absorbing road shocks due to gyroscopic action of the wheels, and with high pressure tyres did not need to be very efficient. Now that Independent Front Suspension (I.F.S.) has generally reduced gyroscopic and other action and low pressure tyres have put up steering torques, efficiency has become much more important and has affected the construction used.
Paper 7: Narrow Vee Engines
Authors: Fessia A. 
Published: June 2010

Many years ago engines with cylinders arranged in two different planes, either the Vee type or the flat twin, were introduced for use on automotive vehicles. The length of straight eight engines was found to be well in excess of the space put at their disposal by the chassis designers. At that time two very interesting engines were produced: the first one was an engine with eight cylinders in two banks placed at an angle of 90°, in which each couple of connecting rods were linked at the same crankpin, the crankshaft having only four throws placed in cross planes. The ingenious Cadillac engine of 1924 had a disposition of throws and counterweights solving every balancing problem. At the same time Lancia had built an eight-cylinder engine of the narrow Vee type and the crankshaft was designed with eight throws displaced in such a way as to give equidistant angles at the firing points. Cutting this engine in half, it was easy to develop a four-cylinder engine, the length of which was well under that of the corresponding in-line engine, the condition of balance being practically the same. The ‘Lancia Lambda’ car was equipped with an engine of this type having a cylinder displacement between 2 and 3 litres. Later it was found that the advantage of shorter length was very important also for the popular size car such as the ‘Lancia Ardea’, having a displacement of 903 cm3. Engines of narrow Vee type must be equipped with overhead gear. The cylinder head at that time was found to be a very difficult piece of foundry work especially if made in light ***alloys. Moreover, the intake and exhaust port of the cylinder head were of very complicated shape and for this reason this type of engine did not find a more general application. On the other side it is very convenient not only for the reduced length but also for the fact that transversal dimensions are practically the same as an engine with in-line cylinders and the height is increased slightly. With regard to four-cylinder engines, one of the most disputed questions is the number of main bearings, which can be two, three or five. Very recently for in-line engines a layout with five main bearings was adopted. This complication is avoided with narrow Vee engines, the reduced length permitting layouts with three or two main bearings. This last solution is sufficient for a power limit of 60 kW. The position of the valves in a one-piece cylinder head is such that a variety of valve gears can be achieved. Their respective merits are discussed.
Paper 8: The NSU Prinz Engine
Authors: Strobel R. M. 
Published: June 2010

As the automobile becomes an indispensable consumer article for all strata of society, its importance as the status symbol of a definite social position declines more and more. This natural process of development has obviously been accelerated by special traffic problems the origin of which must be looked for in the good economic circumstances of the past years. Only they could cause motorization to take such great steps forward. Amongst the many constructions which were created with the intention of combining the requirements of daily professional and town traffic with a comfort sufficient also for extensive holiday travel, the NSU Prinz, as designed in 1955 and then produced in series as Prinz I and II and since May 1961 in its present form, seems to meet the requirements of a large and steadily increasing circle of buyers. The maintainable speed of about 120 km/h, which is quite sufficient even for fast roads and motorways, has been obtained with a motor performance of 30 hp at an air resistance cw = 0·43 and a front area of 1·57 m2, which allows good elbow and head room to the passengers. A four-stroke motor of relatively expensive construction with hemispherical combustion chamber and overhead camshaft was chosen which enables the car to have a good fuel economy. In consideration of town traffic we have stressed the good combustion in the neutral position and the lower partial load range, in order to keep the CO content of the exhaust gases low. We succeeded, in designing the body, in keeping the change of the yawing moment in accordance with the angle of attack, within very modest limits. The dry weight of 537 kg is far below average and could only be attained with considerable effort and after extensive measurements had been carried out. In this manner the drive unit, inclusive of suction and exhaust devices, weighs 100 kg, the chassis (axles, wheels, suspensions and steering parts) 127 kg, the body (raw) 168 kg, glass 28 kg and seats and fittings 114 kg. The ratio of vehicle weight to permissible total weight of 1:1·86 naturally requires an exact study of the chassis and distribution of weight. The centre of gravity changes its position with the different loads in a longitudinal direction by less than 5 per cent from the centre of the wheel base to the front and to the back. This small deviation causes a type of steering behaviour which remains almost static with all loads. In every case the vehicle is slightly under-steered. In this connection we obtained the measurement values for μθ of 0·55 with one passenger and of 0·54 with four passengers. Thus we believe that the driving behaviour of this vehicle takes into account the circumstances of modern traffic and that the usable space offers sufficient comfort for four or five people. For how long the shape of body will correspond to the public taste is a matter of conjecture: however we hope and also believe that the choice which can today be observed, of the simple form which refuses any superfluous decoration, will last for rather a long time.
Paper 1: A Review of Analytical Studies of Reacting or Relaxing Gas Flows
Authors: Clarke J. F. , Cleaver J. W. , Lilley G. M. 
Published: June 2010

The status of the analytical, as opposed to the purely numerical, approach to problems of reacting or relaxing gas flows is examined by way of a summary of the significant results which have been achieved by this means to date. Much of the work deals (inevitably) with a review of the linear theory, although more exact treatments of nozzle flows, shock wave structure, characteristics and first-order wave theories are also dealt with. Finally an attempt is made to assess the limitations and probable lines of development of the analytical study of real gas flows.
Paper 3: Paper 4: Physical Principles of Mhd Generation
Authors: Wright J. K. 
Published: June 2010

A discussion is given of the basic physical processes occurring in magnetohydrodynamic (MHD) generators. In designing a generator two parameters are of importance, namely, the power output per unit volume and the isentropic efficiency ñs which is a measure of the departure of the generation processes from the ideal. It is shown that the maximum electrical output per unit volume of gas is ñs(1-ñs)θ u2 B2 where θ is the electrical conductivity, u the flow speed down the duct, and B the magnetic field strength. The paper describes how the isentropic efficiency depends on the load characteristics, how to calculate the electrical conductivity, the effect of a strong magnetic field on the electrical conductivity and the optimum shape of an MHD duct. A brief account is given of the progress in the development of experimental generators and of the practical problems still to be solved.
Paper 2: A Meter for the Determination of Local Heat-Transfer Coefficient
Authors: Northover E. W. , Hitchcock J. A. 
Published: June 2010

This paper describes the development of a device for the measurement of local heat-transfer coefficient. Such a device was required to measure the local heat-transfer coefficients between heated air and the solid surface of a complex geometric shape, under steady-state conditions. The meter described is based on a method suggested by Gardon (1)† where the heat flux into a thin constantan disc, arranged flush with the fluid-solid interface, produces a radial temperature gradient in the disc. Provision of suitable copper connections at the centre and periphery of the disc gives rise to an e.m.f. proportional to the radial heat flux. This basic principle has been incorporated in an instrument which yields simultaneous measurements of both heat flux and surface temperature. A theory for the meter under steady-state conditions is discussed and shown to be in good agreement with calibrations obtained in a specially designed rig.
Paper 11: The Attenuation of Shock Waves in Rough Ducts
Authors: Woods W. A. 
Published: June 2010

The rule formulated by Whitham (1)† is briefly described and the application of this rule to the attenuation of shock waves in rough ducts is mentioned. A review of previous work on shock wave attenuation shows that most investigators have used smooth-walled ducts for their experiments and a steady-flow, flat-plate boundary-layer analogy for their theory. An alternative approach based upon one-dimensional flow is examined. Previous work concerned with this alternative approach is outlined and the present problem is then explained in detail. The attenuation of moving, one-dimensional shock waves in rough ducts is considered using the theory of characteristics applied to one-dimensional, unsteady, compressible flow, including friction and heat transfer effects and using Whitham's rule. In order to evaluate this, steady-flow friction coefficients and the Reynolds analogy between pipe friction and heat transfer are used. Comparison of the present theory with previous experimental results shows good agreement with half of them. It is suggested that at least part of the difference between the present theory and the other half of the experiments can be attributed to the method used by the previous investigators when evaluating their experimental results.
Paper 20: The Rational Efficiency of Power Plants with External Combustion
Authors: Horlock J. H. 
Published: June 2010

The use of availability in the analysis of engineering power plants is extended to the study of plants with ‘external combustion’, in which heat is transferred from high temperature products of external combustion to an internal closed cycle. A rational definition of plant efficiency is the work output from the internal cycle divided by the maximum work that could be obtained in the change from external reactants to external products at constant (ambient) pressure and temperature. It is shown that the rational efficiency is dependent upon the ratio of the thermal capacities of internal and external fluid flows, and the specific work of the internal cycle.
Paper 23: A Study of the Effect of Space Variable Heat Release on Fluid Flow in a Duct
Authors: Whittley E. R. , Barrow H. 
Published: June 2010

A theoretical and experimental investigation into the effect of non-uniform heating on low-speed fluid flow is reported here. In the theoretical analysis the three-dimensional behaviour of an inviscid, compressible fluid is predicted and a simple expression for the displacement of a streamline is derived. The quasi-two-dimensional flow of air through a rectangular duct, subject to non-uniform heating, is examined and streamline deflections are calculated for various types of flow. Experiments are described in which air flowing through a rectangular duct is subject to a heat flux which varies across the direction of flow. The characteristics of the flow are determined from flow-visualization observations and from measurements of the mass-velocity distribution upstream and downstream of the heated section. The experimental results indicate that streamline deflections may be produced by non-uniform heating. The magnitude of the results showed reasonable agreement with those predicted for the ducted flow of air in the turbulent region, but were generally smaller than those based on the inviscid flow of a compressible fluid. The simplified results of a previous analysis for small heat inputs (1)‡ were shown to be applicable when the total heat added was less than 5 per cent of the initial enthalpy of the flow.
Paper 10: Mechanical Design and Development of Fuel Elements for Gas-Cooled Reactors
Authors: Elliott E. R. , Dann P. R. , Blackburn W. S. 
Published: June 2010

The fuel elements in the uranium-magnox carbon-dioxide-cooled reactors, which are currently operating and under erection in the United Kingdom and other countries, are required to maintain their physical shape and dimensions virtually unchanged during a lifetime which may be as long as five years. During its life in the reactor, the fuel element is subject to forces arising from various causes, e.g. its own weight, because of swelling of the fuel by irradiation, the flow of cooling gas over the element, thermal stresses resulting from charging, load changes and reactor shut-downs and changes in the dimensions of the graphite core which may lead to jamming of the element in the core channel during discharge. Because of the need to economize in neutron-absorbing material the uranium fuel rod itself becomes the major structural member in the element. The effects of these forces on this and the other component parts of the fuel element are examined, out-of-pile testing is described and the changes in design resulting from this prototype testing are indicated. In a short theoretical section, means of predicting fuel-element deformation in the light of creep data are given and probable limits of accuracy noted.
Paper 2: The Use of Gas Turbines in Large Generating Stations
Authors: Dewison D. A. , Parfitt A. W. P. 
Published: June 2010

The importance of electrical auxiliaries in generating stations and the desirability of providing them with an independent source of power is discussed. The requirements of such a source are enumerated and the enumeration points to the conclusion that the aero-type gas turbine is eminently suitable for this duty. The characteristics of the aero-type gas turbine are described and experience with the plant installed at Hams Hall generating station is given. Typical plant under construction is described, and the method of incorporating gas turbines into the electrical distribution system of a power station. Some economic aspects are discussed.