Blast Valve Design and Related Studies : A Review

The protective structures required for performing critical operations are vulnerable to the blast and shock loads of advanced weapons. A blast valve is an important component of such structures for ventilation during normal conditions and for protection from blast/ shock during explosion. In this paper, various aspects of blast valve design and related studies are briefly reviewed. The concept and effects of blast wave, blast impact, numerical modelling and deformation of circular plate (one of the critical components of blast valve) have been discussed. The merits and demerits of sensing mechanisms viz. remote and direct sensing are discussed. The leakage of blast pressure during finite closing period of the valve (one of the critical problems) and the shock tube as a major experimental facility for testing of blast valves are briefly discussed.

Flow Field Analysis of Valve Plate for Hot Blast Valve

The valve plate of the hot blast valve is to rely on itself spiral waterway to cool. In the course of actual use, there is uneven actuality that it is cold and hot for the Valve plate of the hot blast valve. In this article, by means of COSMOSFloworks software, based on classic formula for convective heat transfer of heat transfer, we do flow field analysis for the waterway of the valve plate of DN1800 hot blast valve for certain Heavy Industry Group of our country. And analytical result indicates: Uneven distribution of water velocity in the valve plate is an important reason for causing unequal heat exchange of the valve plate and local thermal shock. In order to improve cooling uniformity, the central flow state of the type valve Plate should be altered and water cooling structure of inner water ring edge should be widen, finally the increase of the life of the valve plate can be reached.

Design of a Compression Pressurized Air Blast Direct Injection System for Small Displacement Two-Stroke Engines

In two-stroke engines replacement of carburetors with direct fuel injection systems greatly reduces engine emissions and fuel consumption by eliminating fuel short-circuiting. Air-blast direct fuel injection using a dedicated air pump has been successfully applied to both two- and four-stroke engines. In this study we re-examine the design of a low cost compression pressurized direct injection system. This system uses gases extracted from the combustion chamber during the compression stroke to supply pressure for the air blast injection, thus eliminating the air pump [1,2]. Gases, predominantly scavenging air, are transferred to a mixing cavity from the combustion chamber via a small (5mm diameter) solenoid poppet valve as the piston rises during the compression stroke. Proper functioning of the system requires careful optimization of the mixing cavity size and the blast valve timing to ensure adequate mixing cavity pressure and fuel atomization. To assist in the optimization of these design parameters a one-dimensional fluid dynamics model has been developed. Parameter sensitivity studies were carried out using the model to determine the optimum cavity size, blast valve timing, and fuel injection duration. These parameters were optimized over a wide range of engine speeds and throttle settings. Results show that a mixing cavity pressure of 500 kPa is attainable over the range of 1000 to 6000 rpm, from closed throttle to wide open throttle (WOT) without cavity pressurization encroaching into the ignition regime. Fuel maps and valve timings are presented and results are contrasted with the carbureted case, showing improved fuel efficiency and emissions for the direct injection system. These data will be used in the design of a physical demonstration engine.