Evaluation of Shock Tube Retrofitted with Fast-Opening Valve for Dynamic Pressure Calibration

Accurate dynamic pressure measurements are increasingly important. While traceability is lacking, several National Metrology Institutes (NMIs) and calibration laboratories are currently establishing calibration capacities. Shock tubes generating pressure steps with rise times below 1 µs are highly suitable as standards for dynamic pressures in gas. In this work, we present the results from applying a fast-opening valve (FOV) to a shock tube designed for dynamic pressure measurements. We compare the performance of the shock tube when operated with conventional single and double diaphragms and when operated using an FOV. Different aspects are addressed: shock-wave formation, repeatability in amplitude of the realized pressure steps, the assessment of the required driver pressure for realizing nominal pressure steps, and economy. The results show that using the FOV has many advantages compared to the diaphragm: better repeatability, eight times faster to operate, and enables automation of the test sequences.

Conceptual aerodynamic design of an executive supersonic passenger aircraft – ESPA

Despite 50 years of technological advancement since the inception of Concorde, research on supersonic passenger aircraft has only recently resulted in design and flight test of several small 12- to 55-passenger business jets with supersonic cruises between Mach 1.2 and 2.2. Analytical research designs of larger 300-passenger aircraft have been conducted only to speeds of Mach 2.0 and 2.2, mainly avoiding moving beyond turbojet propulsion. This research extends on an earlier multifactor regression sizing study to determine in greater design detail what the configuration of a 200-passenger Mach 3.0 aircraft could be using extant technology. This research article is the first part of two and covers the conceptual aircraft design evolution focussing on the aerodynamics, wing and fuselage. In contrast, the second article covers engine conceptual design and placement. Wing shape optimization is performed using fundamental CFD analysis to arrive at a configuration suitable for both subsonic and supersonic flight. Noise considerations and shock wave formation drive further design iterations based on the research literature. The viability of this research design informs a future multidisciplinary optimization like those recently published in the literature for smaller supersonic business jets.

Visualization of the Influence of Changes in the Controlled Dissipative Properties on the Accuracy of the QGDFoam Solver

This work is devoted to the study of the influence of variation of the controlled dissipative properties on the accuracy of the QGDFoam solver and the visual representation of this influence. The work continues a series of studies on the comparative assessment of the accuracy of various numerical methods and solvers built on their basis. To carry out a comparative assessment, a generalized computational experiment for classes of problems with a reference solution is constructed and implemented. A generalized computational experiment based on the synthesis of solutions of mathematical modeling problems, parallel technologies and visual analysis tools makes it possible to obtain solutions not only for individual problems, but for whole classes of problems determined by the specified ranges of key parameters. Accordingly, a comparative assessment of the accuracy of numerical methods is also carried out for a class of problems. Earlier, a similar computational experiment was carried out for a comparative assessment of the accuracy for solvers of the OpenFOAM open source software package on the well-known classical problem of an oblique shock wave formation. One of the solvers participating in the calculations, namely the QGDFoam solver, was the only one of all to have controlled dissipative properties. New generalized computational experiment was implemented to study the effect of variation of the parameter that controls the dissipative properties. The target was to reduce the error in comparison with the reference solution. The research results are presented in this work.