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The formation of shaped charge jets is traditionally studied experimentally using flash X-ray and high-speed camera images. Sequential images obtained through these methods provide insight into the overall properties of the jet, such as jet tip velocity and outline shape. Numerical methods are validated using experimental results of the macroscopic properties by taking absolute velocity contours through the jet and comparing the outline shape. These methods do not describe where, and in which order, discrete parts of the shaped charge liner are located in the jet after formation. Shaped charge jet formation is studied here numerically by tracking the velocity in the flow field using stationary gauges and by placing dynamic gauges on the shaped charge liner. This method provides insight into the physical mechanism of jet formation. It is generally assumed that the shaped charge jet forms from liner inversion, where the liner tip becomes the jet tip that first penetrates the target. This work shows that the liner tip does not form part of the jet but is rather absorbed into the slug. Similarly, PER theory assumes that the outer part of the liner (next to the explosive) flows into the slug and the inner part flows into the jet. It is shown here that this assumption is not valid in all cases. This study is a proof of concept to highlight the advantages of using the method of simultaneous liner and flow field velocity tracking to aid shaped charge optimization activities. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of alternative refrigerants with low Global Warming Potential and zero Ozone Depletion Potential. The application here is the working fluid in vapour compression refrigeration cycles. A vapour compression refrigeration cycle model was developed in MATLAB and tested with refrigerants R1234ze(E), R134a, R32, R407C and ECP410a. The performance of each refrigerant was analysed against the baseline refrigerant R134a using cooling capacity, coefficient of performance, Carnot coefficient of performance and compressor power as the performance parameters. The results show that the cooling capacity of the vapour compression refrigeration cycle can be successfully optimized by 159.44% with ECP410a, 70.28% with R32 and 5.96% with R407C. The tests also demonstrated that an increase in coefficient of performance of 28.05% with ECP410a, 217.92% with R32 and 32.21% with R407C can be achieved. Whereas the results showed that the use of R1234ze(E) yielded a decrease in performance of -9.52% for cooling capacity and -16.10% for coefficient of performance. It was also determined that the use of R32 could yield a decrease in compressor power by 46.50%. [ABSTRACT FROM AUTHOR]

This note proposes a non-inertial similarity solution for the classic von Kármán swirling flow as perceived from the rotational frame. The solution is obtained by implementing non-inertial similarity parameters in the non-inertial boundary layer equations. This reduces the partial differential equations to a set of ordinary differential equations that is solved through an integration routine and shooting method. [ABSTRACT FROM AUTHOR]