Second Mode Suppression in Hypersonic Boundary Layer by Roughness: Design and Experiments

摘要: T HE performance of hypersonic transportation vehicles and reentry is significantly affected by the laminarturbulent transition boundary-layer flows over vehicle surfaces, as has a first-order impact on lift, drag, stability, control, surface heating. For vehicle, can lead to an increase in heating rate factor five or more. Hence, understanding mechanisms prediction locations are critical development future [1]. One important area study effect roughness transition. Despite several decades experimental, theoretical, numerical studies, still not fully understood [2].Most previous research focused mainly tripping flow using elements. However, there have been few reported experimental studies that demonstrate delay elements under certain circumstances. James [3] experimentally studied effects Mach number fin-stabilized hollow tube models free flights. found that, for someMach numbers, exists optimum height results longer laminar run rough than smooth surface. In other words, element delays process rather promoting it. Holloway Sterrett [4] performed experiment Langley 20 in. 6 tunnel flat plate embedded with spherical They cases smallest diameters, was delayed conditions. Although they did investigate reasons conditions behind delay, hypothesized creates separated mixing layer more stable at higher numbers.More recently, Fujii [5] experiments 5 deg half-angle sharp cone 7. The tests were completed stagnation pressures 2, 4, MPa. It higher-pressure cases, onset when wavelength wavy wall roughly equal unstable second-mode wavelength. weak, it discernible, repeatability remarkably good. speculated relationship between disturbance leads mechanism unknown explored. addition testing, delay. Marxen et al. [6] growth flat-plate boundary atMach 4.8 localized two-dimensional (2-D) strongly damped downstream around separation region, which agrees Sterrett’s hypothesis. investigated. At same time, Duan [7] from University California, Los Angeles (UCLA) 2-D damp disturbances if placed location where slow boundarylayer mode (mode S) fast F) phase velocity (the synchronization location). details work UCLA group will be discussed next paragraph. Riley [8,9] also numerically stability characteristics 4 wedge. On wedge, imposed convex concave panel buckling (compliant panel) different locations. near trailing edge move further downstream. hand, Egorov [10] simulations supersonic grooved plate. Their motivated Balakumar [11] [12], showed second remains neutral region 5.5 compression corner. Based result intention generate short local separations thewavy decrease growth. form nine round arc cavities. thewavywall design damps range high-frequency relevant instability. Bountin [13] later confirmed byEgorovet secondmode bandwhile enhances them lower frequencies. data disturbances, only but wide frequencies wavelengths. these results, argued stabilization secondmodeby due altering themean instead interference itself. Since 2009, purpose simulating finite elements, developed highorder cut-cell method [14]. new then applied 5.92 [7,14]. Different idea, [10], relative Received December 2014; revision received 7 April 2015; accepted publication 8 published online June 2015. Copyright © 2015 Kahei Danny Fong. Published American Institute Aeronautics Astronautics, Inc., permission. Copies this paper may made personal internal use, condition copier pay $10.00 per-copy fee Clearance Center, 222 Rosewood Drive, Danvers, MA 01923; include code 1533-385X/15 correspondence CCC. *Graduate Research Assistant, Mechanical Aerospace Engineering Department. Student Member AIAA. ResearchAssociate,Mechanical EngineeringDepartment. Senior Professor,Mechanical andAerospace Associate Fellow Graduate School Astronautics. Student, **Professor,