Semarak Engineering Journal

Relocation of the Double-bump on the Ramp of a Supersonic Air-intake for its Improved Performance

Thu, 30 May 2024 00:00:00 +0000

The performance of a supersonic air-intake is important for efficient combustion in an air-breathing engine. Recent literature shows study of the design of a supersonic air-intake, with bumps located on its ramp surface. The bumps generate oblique shocks which should result in pressure jump downstream of the shocks. This would result in compressed and decelerated flow at the exit of the intake, for efficient combustion downstream. However, some recent studies found that a double-bump degrades the performance of the air-intake compared to a single bump. This sounds counter-intuitive. In this work, this problem is investigated and an improved location for the double-bump is proposed based on physics of high-speed gas dynamics. Computational analysis is then done to analyze the performance of the supersonic air-intake with an incoming freestream flow of Mach 2.2, using CFD package ANSYS Fluent. The computational methodology is first validated using results of surface pressure distribution on the wall of the intake, for a standard test case available in literature. The methodology is then applied for the supersonic air-intake with the proposed location of the double-bump. The resulting Mach contours and pressure contours are discussed in relation to the compression and Mach number obtained at the exit of the intake. The results show that with the location proposed in this work, the double-bump results in a system of shocks and reflected shocks which are contained well within the air-intake. This results in higher pressure recovery and lower Mach number at the exit of the intake, compared to a single-bump intake. As the air with higher static pressure and lower speed enters the combustion chamber downstream, both these favourable features should help in more efficient combustion.

Resonance Sensors of Motion Parameters

Amirov Sulton, Sulliev Absaid, Mukhtorov Usmon, Badretdinov Timur — Thu, 30 May 2024 00:00:00 +0000

The article studies the design features of known and developed electromagnetic resonant sensors of motion parameters and develops their mathematical models, which make it possible to study the main technical characteristics of these sensors. A comparative analysis of the obtained expressions of the output signals and the sensitivity of the known and proposed electromagnetic resonant sensors of motion parameters shows that the sensitivity of the proposed sensor due to the implementation of each magnetic field source in the form of a multi-turn magnetic circuit with an excitation winding section, the turns of which cover all turns of the multi-turn magnetic circuit, in (where - the number of turns of a multi-turn magnetic circuit) is times greater than the sensitivity of a known sensor, and the accuracy of measuring the speed of movement of the moving winding of the controlled object is higher due to the reduction to a minimum of the level of the alternating component of the output signal, which is not proportional to the speed of movement, which is achieved by picking up a signal proportional to the linear speed of movement of the moving measuring winding, from the load terminals to a moving measuring winding tuned to voltage resonance.

Effect Of Nozzle Temperature on The Physical Properties of Inconel 718 Specimens Additively Manufactured by Fused Filament Fabrication

Thu, 30 May 2024 00:00:00 +0000

In this study, the effect of nozzle temperature, (T_n) (varied between 200°C and 300°C) during the printing stage on the relative density, hardness, and porosity of sintered Inconel 718 (IN 718) specimens are investigated for the first time. The results show a general trend of increasing relative density and hardness values, as well as reduced porosity with an increase in T_n values. The highest relative density (92.34%), hardness (188 HV) and lowest porosity (7.66%) are all achieved at T_n=290°C. The outcomes of this study establish the profound impact of adjusting processing parameters even at the initial printing stage towards the properties of the sintered parts.