Influence of Cavity Depth on Ignition and Flameholding Modes within a Scramjet Combustor

Abstract Background This study investigated the prevalence of labial bone perforation (LBP) related to the associated anatomic factors in anterior mandibular region using a virtual immediate implant placement procedure. Methods Series qualified CBCT images of 149 participants (894 teeth) were selected to analyze the assigned anatomical parameters, including concavity depth, concavity angle, torque, and deep bone thickness. Four classes of crestal and radicular dentoalveolar bone phenotypes (CRDAPs) of mandibular anterior teeth were categorized according to the thickness of dentoalveolar bone at both crestal and radicular zones. Data were adjusted for categorical (gender and CRDAP) and continuous (age, cavity angle, cavity depth, and deep bone thickness) variables using a multivariable logistic regression analysis with generalized estimating equation method. Results The overall probability of LBP after virtual implant placement was 21.6%. There is statistically significant higher prevalence of LBP at canine (28.5%) and CRDAP class II (29.2%) regions (p < 0.001). After adjusting confounding variables, CRDAP class II and class IV regions are more likely to have LBP when compared with CRDAP class I (control) regions (p < 0.01). The risk of LBP at canine site is 6.31 times more likely than at the central incisor (control) (p < 0.01). Conclusions Using a virtual immediate implant placement technique, the prevalence of LBP is significantly higher at the mandibular canine site and thin radicular dentoalveolar phenotype in the anterior mandibular region.

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Enhancing mixing features in supersonic flow through geometric correction of the cavity depth relative to the height of the combustion chamber

Journal of the Brazilian Society of Mechanical Sciences and Engineering ◽

10.1007/s40430-021-02832-w ◽

2021 ◽

Vol 43 (3) ◽

Author(s):

Vahideh Dashti Rahmat Abadi ◽

Mohsen Agha Seyed Mirzabozorg ◽

Saeid Kheradmand

Keyword(s):

Supersonic Flow ◽

Combustion Chamber ◽

Geometric Correction ◽

Cavity Depth ◽

Flow Through

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Numerical investigation of combustion characteristics of upstream crescent cavities in a scramjet combustor

Acta Astronautica ◽

10.1016/j.actaastro.2021.05.027 ◽

2021 ◽

Author(s):

Tim Roos ◽

Adrian Pudsey ◽

Hideaki Ogawa

Keyword(s):

Numerical Investigation ◽

Combustion Characteristics ◽

Scramjet Combustor

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Frequency–Amplitude Relationship of a Nonlinear Symmetric Panel Absorber Mounted on a Flexible Wall

Symmetry ◽

10.3390/sym13071188 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1188

Author(s):

Yiu-Yin Lee

Keyword(s):

Elliptic Integral ◽

Algebraic Equations ◽

Cavity Depth ◽

Nonlinear Algebraic Equations ◽

Flexible Panel ◽

Flexible Wall ◽

Elliptic Integral Method ◽

Flexible Panels ◽

Relationship Of ◽

Panel Absorber

This study addresses the frequency–amplitude relationship of a nonlinear symmetric panel absorber mounted on a flexible wall. In many structural–acoustic works, only one flexible panel is considered in their models with symmetric configuration. There are very limited research investigations that focus on two flexible panels coupled with a cavity, particularly for nonlinear structural–acoustic problems. In practice, panel absorbers with symmetric configurations are common and usually mounted on a flexible wall. Thus, it should not be assumed that the wall is rigid. This study is the first work employing the weighted residual elliptic integral method for solving this problem, which involves the nonlinear multi-mode governing equations of two flexible panels coupled with a cavity. The reason for adopting the proposed solution method is that fewer nonlinear algebraic equations are generated. The results obtained from the proposed method and finite element method agree reasonably well with each other. The effects of some parameters such as vibration amplitude, cavity depth and thickness ratio, etc. are also investigated.

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Influence of tip clearance and cavity depth on heat transfer in a cutback squealer tip

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410020964690 ◽

2020 ◽

pp. 095441002096469

Author(s):

Weijie Wang ◽

Shaopeng Lu ◽

Hongmei Jiang ◽

Qiusheng Deng ◽

Jinfang Teng ◽

...

Keyword(s):

Heat Transfer ◽

Suction Side ◽

High Heat ◽

Tip Clearance ◽

Tip Leakage Flow ◽

Trailing Edge ◽

Cavity Depth ◽

High Heat Transfer ◽

Blade Tip ◽

High Heat Transfer Coefficient

Numerical simulations are conducted to present the aerothermal performance of a turbine blade tip with cutback squealer rim. Two different tip clearance heights (0.5%, 1.0% of the blade span) and three different cavity depths (2.0%, 3.0%, and 6.0% of the blade span) are investigated. The results show that a high heat transfer coefficient (HTC) strip on the cavity floor appears near the suction side. It extends with the increase of tip clearance height and moves towards the suction side with the increase of cavity depth. The cutback region near the trailing edge has a high HTC value due to the flush of over-tip leakage flow. High HTC region shrinks to the trailing edge with the increase of cavity depth since there is more accumulated flow in the cavity for larger cavity depth. For small tip clearance cases, high HTC distribution appears on the pressure side rim. However, high HTC distribution is observed on suction side rim for large tip clearance height. This is mainly caused by the flow separation and reattachment on the squealer rims.

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