The attitude control of a rocket engine using the control surfaces becomes cumbersome particularly in larger rockets with high payload. In such cases, a more effective means of producing forces for controlling the flight is the deflection of exhaust gases, referred to as the gas-dynamic steering or the thrust vector control. In this study, the effect of a strut on the exhaust gas deflection, deployed at the locations; 0.62 L, 0.72 L and 0.8 L in the divergent-portion of a Mach 1.84 nozzle at over-expanded, correctly-expanded and under-expanded states of the jet, has been experimentally investigated. The level of expansion at the nozzle exit is varied by changing the settling chamber pressures from 4 bar to 8 bar, in steps of 2 bar. Further, to study the effect of aspect ratio, the height of strut is varied as 1.5 mm, 2.5 mm and 3.5 mm. The strut of height 3.5 mm, deployed at x/L = 0.72, is found to be the most effective thrust vector control at overexpanded conditions; with a maximum jet deflection of about 3.6 o , obtained at a settling chamber pressure of 4 bar. The Schlieren flow visualization images confirm the findings of wall static pressure data.

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The present study numerically investigates some novel modifications to augment the performance of the H-type finned tube banks, which are widely used in waste heat recovery in industries. The imposed modifications upon the original H-type finned tube banks include the following: (1) Design 1 contains some triangular cuts at the edge of the original rectangular fin; (2) Design 2 modifies the original rectangular geometry into a trapezoid shape; (3) Design 3 renders the original rectangular cross-section fin thickness into trapezoid cross-section; and (4) Design 4 changes the original rectangular shape into a circular shape. Based on the simulations, it is found that Design 1 shows barely any improvements in the heat transfer performance and surface area reduction. Design 2 can provide some weight saving and surface area reduction at a slightly inferior heat transfer performance. Design 3 can offer up to 14% improvements in the overall heat transfer performance without any pumping power penalty. Yet, Design 4 provides the maximum weight saving as compared to the original reference case. With 3–9% lesser surface area than the reference case, Design 4 still offers marginally higher heat transfer performance.

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