Aerospace Science and Technology
Mohammad Hossein Moghimi EsfandAbadi; Adnan Mohammadi; Mohammad Hassan Djavareshkian
Abstract
This research delves into the intricate realm of supersonic inlet design for ramjet engines, honing in on the critical aerodynamic considerations and optimization of performance factors. At Mach 2.5, the study meticulously scrutinizes pivotal design parameters, including the placement and number of inclined ...
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This research delves into the intricate realm of supersonic inlet design for ramjet engines, honing in on the critical aerodynamic considerations and optimization of performance factors. At Mach 2.5, the study meticulously scrutinizes pivotal design parameters, including the placement and number of inclined shocks, cowl-lip positioning, throat area, spike location, and diffuser length. Computational fluid dynamics simulations are harnessed to unravel the intricate flow dynamics and assess the proposed inlet geometry's performance.The findings reveal a nuanced relationship between back pressure and shock wave positioning, where increasing back pressure initiates a shift in the shock wave, impacting the flow state. The paper delineates this transition, emphasizing the pivotal back pressure range of 300,000 to 350,000 pascals, where optimal shock wave alignment corresponds with design parameters, achieving a supercritical state.However, elevating back pressure beyond this range triggers a sub-critical state and mass flow overflow as the shock exits the throat.the study explores various performance metrics, encompassing drag coefficient, distortion coefficient, mass flow ratio and total pressure recovery under varying back pressure conditions. The outcomes underscore the merits of higher back pressures, which mitigate drag coefficient and distortion while amplifying TPR.In the sub-critical state, MFR diminishes due to shock wave displacement beyond the intake opening.This research illuminates the intricate dance of aerodynamics within ramjet engine inlets and underscores the paramount significance of optimizing inlet geometry to unlock heightened performance. It effectively encapsulates the essence of the full article, enticing readers to embark on a deeper exploration of this crucial area of aerospace engineering.
Alireza Moghaddasi; Mohammad Hassan Djavareshkian
Abstract
In this paper a comparison of Weighted Essentially Non-Oscillatory (WENO) scheme is presented and different kinds are compared. High resolution schemes are one of the best ways decreasing the cost of processes and also increasing the resolution as is clear. Different WENO’s influence on the weights ...
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In this paper a comparison of Weighted Essentially Non-Oscillatory (WENO) scheme is presented and different kinds are compared. High resolution schemes are one of the best ways decreasing the cost of processes and also increasing the resolution as is clear. Different WENO’s influence on the weights that applies on the neighborhood of the cells that is supposing to be calculated. Mentioned schemes, were tested on wave equation at first and in continued with the first and second dimension test cases. 3rd ,5th, 7th and 9th order of JS-WENO, MWENO, ZWENO and MZWENO are compared in Goethe tests. This scheme was applied in finite volume characteristic wise algorithm in order to reach much more accuracy. Buckley-Leverette, Sod shock tube, Shu-Osher, Lax test, Riley-Taylor instability and double Mach reflection test cases was compared. As the result, MZWENO in equal order with the other ones would report more accurate reply. But as a new research here we showed that e.g. although MZWENO 5th order could promote the accuracy of the scheme up to about two times higher, but the cost of computing will increase more than the JS 7th order one. So, it is concluded that employing 7th order of JSWENO leads to higher accuracy with less computational costs.