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This paper aims to consolidate the results of various researchers focusing the different applications, so that this paper could become the torch bearer for the futuristic researchers working in the domain of cold gas dynamics spray coating.

A study on the cold spray coating is presented by summarizing the data present in literature. Important factors such as coating temperature, pressure, coating thickness, particle size, which affect the erosion-corrosion (E-C) resistance, physical and mechanical properties of boiler steel are stated. This paper also addresses the use of cold spray coating and compares it with other different thermal spray processes.

From the literature review, it was noticed that cold spray technology is best as compare to other thermal spray processes to reduce porosity, increase hardness, adhesion strength and retention in properties of feedstock powders.

Cold spray coating technology has a great potential in almost every field especially in restoration of surfaces, generation of complex surface, biomedical application, resist hot corrosion, wear, oxidation and erosion corrosion.

Application of cold spray technology may exhibit significant benefits for the additive manufacturing process, particularly for producing intricate objects. To ascertain the feasibility of such an application, this paper aims to present a numerical investigation of the effect of scaling down a convergent-divergent (de Laval) nozzle, which is typically used in the cold spray industry, on the compressible flow parameters and thermal characteristics.

The Navier–Stokes equations and energy equation governing compressible flow are numerically solved using a finite volume method with a coupled solver. The conjugate heat transfer technique is used to couple fluid and solid heat transfer domains and predict the local heat transfer coefficient between the solid and fluid. The use of various RANS turbulence models has also been investigated to quantify the effect of the turbulence model on the simulation.

The numerical results reveal that the flow and thermal characteristics are altered as the convergent-divergent nozzle is scaled down. The static pressure and temperature profiles at any section in the nozzle are shifted toward higher values, while the Mach number profile at any section in the nozzle is shifted toward a lower Mach number. The turbulent kinetic energy at the nozzle exit increases with the scaling down of the nozzle geometry. This study also provides convincing evidence that the adiabatic approach is still suitable even though the temperature of the nozzle wall is extremely high, as required for industrial application. Results indicate that it is feasible to use the available capabilities of the cold spray technology for additive manufacturing after scaling down the nozzle.

The idea of adopting cold spray technology for additive manufacturing is new and innovative. To develop this idea into a viable commercial product, a thorough understanding of the flow physics within a cold spray nozzle is required. The simulation results discussed in this paper demonstrate the effect that scaling down of a convergent-divergent nozzle has on the flow characteristics in the nozzle.

This study aims to clarify the mechanism of film hole location at the span-wise direction of an internal cooling channel with crescent ribs on the adiabatic film cooling performance, three configurations are designed to observe the effects of the distance between the center of the ellipse and the side wall(Case 1, l = w/2, Case 2, l = w/3 and for Case 3, l = w/4).

Numerical simulations are conducted under two blowing ratios (i.e. 0.5 and 1) and a fixed cross-flow Reynolds number (Re_c = 100,000) with a verified turbulence model.

It is shown that at low blowing ratio, reducing the distance increases the film cooling effectiveness but keeps the trend of the effectiveness unchanged, while at high blowing ratio, the characteristic is a little bit different in the range of 0 = x/D = 10.

These features could be explained by the fact that shrinking the distance between the hole and side wall induces a much smaller reserved region and vortex downstream the ribs and a lower resistance for cooling air entering the film hole. Furthermore, the spiral flow inside the hole is impaired.

As a result, the kidney-shaped vortices originating from the jet flow are weakened, and the target surface can be well covered, resulting in an enhancement of the adiabatic film cooling performance.

In an aircraft, a gas turbine having a truncated tail cone over which turbine effluent flows, the small end of said truncated tail cone being open and directed rearwardly, and a rocket motor within said truncated tail cone and issuing its effluent through the rearward open small end thereof, said rocket motor having selectively operable liquid fuel and liquid oxidizer feed mechanisms driven by said gas turbine and disposed within said tail cone and forward of said rocket motor.

An aircraft having wings with sharply swept‐leading‐edges has a pair of members providing auxiliary lift surfaces, which members arc movable between a retracted position within the wings and an extended position in which the lift surfaces project laterally of the aircraft, and a source of pressure fluid, each member having nozzle means at or adjacent to its trailing edge, which nozzle means, in the extended position of the lift surfaces, faces downwards and from which pressure fluid from the source can be expelled at high speed downwardly in the form of a sheet extending laterally of the aircraft to provide an effect equivalent to additional lift surfaces for the aircraft. The aircraft comprises a pointed body 5, sharply swept low aspect ratio wings 6, 7 and a power plant 34. Supplementary aerofoils 12, 13 arc pivotally mounted to extend transversely from or to retract into the leading edges of wings 6, 7 respectively under the action of jacks 33. The trailing edges of aerofoils 12, 13 carry slots which arc supplied with pressure gas from power plant 34, the gas emerging as thin sheets which enhance the lift of the aerofoils. Without such device the aerofoils would have to be of greater chord as indicated by dotted lines 10, 11. The flow of gas from the slots (which may comprise a plurality of discrete apertures) may be varied differentially to provide yawing or roll control of the aircraft. Another embodiment is described in which the supplementary aerofoils are of sector shape instead of the rectangular form shown.

THE advent of the modern jet‐type power plant for aviation has greatly accelerated the development of new high‐temperature ceramic materials. These power plants are essentially high‐temperature engines which convert heat energy into work. The greater the differential in temperature of the air between the beginning and end of the conversion, the greater the efficiency of the engine. Consequently, turbo‐jets, gas turbines, ram‐jets and rockets have created a demand for materials which will withstand elevated temperatures and vibration and possess good resistance to thermal shock. Ceramic materials seem to offer the best promise of providing these desirable characteristics.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Technical Reports and Translations of the United States National Aeronautics and Space Administration and publications of other similar Research Bodies as issued.

Many small holes need to be drilled in printed circuit boards to achieve a high packing density of circuit components. Even with NC control, conventional mechanical techniques are relatively slow and holes smaller than 035 mm diameter are difficult to achieve in production. Laser drilling has been suggested as a potentially fast technique capable of drilling small holes, so trials have been conducted on thin, flexible kapton board, and on 08 mm and 16 mm thick epoxide woven glass fabric board with 12 and 36 micron thick copper cladding. Using a 600 W CO2 laser, the proposed technique was to pre‐etch holes in the copper which would then act as a mask to the beam, so drilling only where etched holes existed. This technique was feasible on the flexible board, but not on the thicker boards because of damage to the copper. Using a pulsed Nd‐YAG laser to drill through both copper and laminate gave good results, but more work is necessary to eliminate occasional delamination of the copper around the hole. Through‐hole plating of the drilled holes appeared to present no special problems.

In the very able and striking address which he recently delivered before the Society of Arts, Sir WILLIAM PREECE insisted that commercial success—whether of a man, of a body of men, or of a nation—is referable to the working of distinct laws, the recognition and study of which may justly be said to constitute a “science of business.” In terms rendered the more severe by their dispassionate and moderate character, Sir WILLIAM referred to the lamentable ignorance displayed by the legislature, by the manufacturer, and by the general public, of what may bo regarded as the most elementary facts and methods upon which such a science must be based. He pointed to the loose and bungling character of our commercial legislation; to the lack of co‐operation and combination; to the nonexistence of a properly organised and effective consular service whereby full information could be supplied and the interests of British trade, both home and colonial, might be studied and advanced; and finally to the lethargy of British producers and manufacturers themselves, who allow foreign competitors to drive them out of even their own home markets without making an effort to discard the old‐fashioned and worn‐out methods which have given those competitors the advantage. Of late years the warning voice has been raised from time to time, but it has been as a voice crying in the wilderness. The remarkable speech delivered at the Guildhall by H.R.H. THE PRINCE OF WALES is fresh in the recollection of those who are not too drowsy or too indifferent to appreciate the vital nature and the magnitude of the evil. In 1891 Lord PLAYFAIR stated that if the Americans were right in principle in the management of some of their commercial concerns, “the whole policy of the United Kingdom was founded on a gigantic error, and must lead to our ruin as a commercial nation.” Sir WILLIAM PREECE is amply justified in attaching severe blame to the British manufacturer and producer. They have allowed “the Americans and the Germans to oust them out of their own markets, not by any superiority in the quality of their goods, but by lower prices, by superior knowledge of the demands of the markets, by the establishment of new markets, by better direct communication with foreign countries, by superior methods in business ways, by establishing regular intelligence departments, and, above all, by possessing and exercising superior commercial technical knowledge,” “and,” continued Sir.WILLIAM, “they must lay aside the commercial habits of their fathers.” With regard to food‐products, for instance, can it be truly said that any adequate steps are taken to secure any satisfactory and permanent improvement of the national food supply with respect to purity and good quality? Has anything been done, with governmental or legislative assistance, to make a systematic study of, and provide authoritative information upon such questions as the sources from which food stuffs are obtained, the adequacy or inadequacy of supplies, the true value of home‐produce and the advantages of utilising colonial products as far as possible? The answers to these questions can only be emphatically in the negative. There is no civilised country in the world in which the producer and vendor of adulterated, impoverished, and inferior articles of food can cany on their nefarious practices with more impunity, in certain respects, than in the United Kingdom, although, originally, we led the way in framing legislative enactments on these all‐important matters. At every port of entry today we might most appropriately set up the old waste‐land notice that “rubbish may be shot here.” As we offer all the necessary facilities, and as they are being taken advantage of more and more, wo might also freely advise that “rubbish should bo manufactured here” as well, What steps do British producers and manufacturers of articles of food take to move with the times, to set their houses in order, to protect themselves, and to enable the public to differentiate between the good and the bad? In the vast majority of instances the attitude they adopt is still one of unmasterly inactivity, except in the direction of unscientific and clumsy advertisement. On this they spend enormous sums without proportionate returns, and in following this course they constantly lay themselves open to condemnatory criticism by the publication of unauthorised and exaggerated statements which, in spit© of CARLYLE'S dictum “mostly fools,” are now merely received by the general public with a shrug of the shoulders. The time has come when, in order not only to develop their trade but in order to keep it, British manufacturers must give evidence of an independent and authoritative character to justify the faith that is presumably in them in recommending their goods to the public. Those who refuse to entertain new ideas and who are content to rest in a semi‐comatose condition on the achievements of the past,—relying merely on the possession of the hitherto reputable “name of the firm,”—by the operation of an inexorable law must inevitably drop out of the race.