Determination of the efficiency of a multiple launch rocket system

Up-to-date multiple launch rocket systems (MLRSs) are adopted by many countries of the world, and they are an effective weapon against dispersed multiple targets. Developing and upgrading MLRSs calls for estimating their efficiency with the aim to select an optimum alternative. For an MLRS, the basic measure of area target destruction efficiency is the relative damage area. This measure depends on the damage area of the MLRS itself (extent of damage by one salvo). The paper suggests a relative criterion that allow one to estimate and optimize the salvo damage area. The criterion is based on the ratio of the salvo damage area to the maximum damage area and that of the undamaged area to the coverage area. The coverage area is defined as the area of the enveloping convex polygon for all points of missile impact in a salvo. It is shown that the domain of variation of the suggested criterion is the interval [0, 1]. Using the suggested criterion for 4 points of missile impact with a circular damage area, two basic structures are studied: a rhomb (two regular triangles) and a square. For them, optimum distances between the missile impact points that maximize the destruction level are determined. It is shown that the obtained optimum arrangement of missile impact points allows one to bring the extent of damage for the square structure to the more optimum rhomb layout (represents a part of the hexagonal structure, which is the most efficient from the standpoint of the packing problem). For a 16-missile salvo, it is shown that from the standpoint of the suggested criterion there exists an optimum relation between the missile damage area (radius) and the technical scattering parameters. The maximum value of the criterion for a missile salvo with account for the technical spread does not exceed 0.33 and is much lower than the value that can be obtained for the optimum structures (rhomb and square). The paper shows possibilities of using the criterion in deciding on optimum missile impact points with account for various typical targets within a multiple target and missile damage area configurations other than a circle.

Effects of Several Major Irreversibilities on the Thermodynamic Performance of a Regenerative MHD Power Cycle

This communication presents the thermodynamic analysis along with a detailed parametric study of an irreversible regenerative MHD power cycle. The power output is adopted as the objective function and optimized with respect to the cycle temperature ratio for a typical set of operating parameters. The power output is found to be an increasing function of the effectiveness and the heat capacitance rates on the hot- and cold-side reservoirs, the regenerative effectiveness, and the compressor and generator efficiencies, while it is found to be a decreasing function of the working fluid heat capacitance rates and the Mach number. The effects of the cold-side effectiveness and heat capacitance rate are found to be more than those of the other side effectiveness and heat capacitance rates on the performance of the cycle. The effect of the compressor efficiency is found to be more than that of the generator efficiency on the power output while it is reverse in the case of thermal efficiency. It is also found that there is an optimum relation among the various heat capacitance rates at which the cycle attains the maximum performance.

Iron–Aluminium-Base Alloys with Strengthening Laves Phase for Structural Applications at High Temperatures

Fe-Al-Ta alloys with the ternary Laves phase Ta(Fe0.5+x, Al0.5-x)2 are studied experimentally with the objective of clarifying the effect of Laves phase precipitation and atomic ordering on the deformation characteristics of such Fe-Al-base alloys. The present study concentrates on the hardening effect of the Laves phase in ordered and disordered Fe-Al-Ta alloys with Al contents between 16 and 45 at.% showing the A2 disorder or the DO3 or B2 order. Ta has a low solubility in Fe-Al alloys which is beneficial for slowing down precipitate coarsening. Small amounts of Laves phase together with atomic ordering increase the yield stress and affect ductility in a complex way. The alloys with 1% Ta exhibit a high oxidation resistance. The continuing work aims at adjusting the Al and Ta content for an optimum relation of high-temperature strength and low-temperature ductility with maintaining a sufficient oxidation resistance.

Optimization on the Performance Characteristics of a Magnetic Ericsson Refrigeration Cycle Affected by Multi-Irreversibilities

A general irreversible cycle model of a magnetic Ericsson refrigerator is established. The irreversibilities in the cycle model result from the finite-rate heat transfer between the working substance and the external heat reservoirs, the inherent regenerative loss, the additional regenerative loss due to thermal resistances, and the heat leak loss between the external heat reservoirs. The cycle model is used to optimize the performance of the magnetic Ericsson refrigeration cycle. The fundamental optimum relation between the cooling rate and the coefficient of performance of the cycle is derived. The maximum coefficient of performance, maximum cooling rate and other relevant important parameters are calculated. The optimal operating region of the cycle is determined. The results obtained here are very general and will be helpful for the optimal design and operation of the magnetic Ericsson refrigerators.

Performance and optimization of gas turbines with real gas effects

The influence of various levels of mathematical modelling on gas turbine performance is systematically analysed. It is shown that internal combustion with real gas effects gives rise to an optimum turbine entry temperature which does not arise in a perfect gas analysis and has not been described previously in the literature. At any pressure ratio, the maximum possible efficiency with real gas effects is significantly lower (15-20 per cent) than the maximum possible value predicted by a perfect gas analysis. An explicit equation has been derived for determining the optimum pressure ratio as a function of turbine entry temperature and component efficiencies. It is shown that the optimum design depends very strongly on turbine and compressor efficiencies. It is demonstrated that the optimum relation between pressure ratio and turbine entry temperature depends strongly on whether the optimization is carried out at fixed pressure ratios or at fixed temperatures. All previous references seem to have considered only the latter method.