Dependence of Steady Mach Reflections on the Reflecting-Wedge Trailing-Edge Angle

AIAA Journal ◽  
10.2514/2.28 ◽  
1997 ◽  
Vol 35 (11) ◽  
pp. 1780-1782 ◽  
Author(s):  
G. Ben-Dor ◽  
T. Elperin ◽  
H. Li ◽  
E. Vasiliev ◽  
A. Chpoun ◽  
...  
Keyword(s):  
Trailing Edge ◽  
Edge Angle

Dependence of steady Mach reflections on the reflecting-wedge trailing-edge angle

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1780-1782
Author(s):  
G. Ben-Dor ◽  
T. Elperin ◽  
H. Li ◽  
E. Vasiliev ◽  
A. Chpoun ◽  
...  
Keyword(s):  
Trailing Edge ◽  
Edge Angle

The influence of the trailing edge angle of the micro centrifugal impeller on the performance of the centrifugal compressor

2021 ◽  
pp. 1-15
Author(s):  
Xu Yu-dong ◽  
Li Cong ◽  
Lv Qiong-ying ◽  
Zhang Xin-ming ◽  
Mu Guo-zhen
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Impeller ◽  
Centrifugal Compressors ◽  
Trailing Edge ◽  
Sweep Angle ◽  
Impeller Blade ◽  
Bending Angle ◽  
Edge Angle ◽  
Isentropic Efficiency

In order to study the effect of the trailing edge sweep angle of the centrifugal impeller on the aerodynamic performance of the centrifugal compressor, 6 groups of centrifugal impellers with different bending angles and 5 groups of different inclination angles were designed to achieve different impeller blade trailing edge angle. The computational fluid dynamics (CFD) method was used to simulate and analyze the flow field of centrifugal compressors with different blade shapes under design conditions. The research results show that for transonic micro centrifugal compressors, changing the blade trailing edge sweep angle can improve the compressor’s isentropic efficiency and pressure ratio. The pressure ratio of the compressor shows a trend of increasing first and then decreasing with the increase of the blade bending angle. When the blade bending angle is 45°, the pressure ratio of the centrifugal compressor reaches a maximum of 1.69, and the isentropic efficiency is 67.3%. But changing the inclination angle of the blade trailing edge has little effect on the isentropic efficiency and pressure ratio. The sweep angle of blade trailing edge is an effective method to improve its isentropic efficiency and pressure ratio. This analysis method provides a reference for the rational selection of the blade trailing edge angle, and provides a reference for the design of micro centrifugal compressors under high Reynolds numbers.

The wave drag at zero lift of slender delta wings and similar configurations

1956 ◽  
Vol 1 (3) ◽  
pp. 337-348 ◽  
Author(s):  
M. J. Lighthill
Keyword(s):  
Uniform Distribution ◽  
Present Method ◽  
Wave Drag ◽  
The Body ◽  
Slender Body ◽  
Trailing Edge ◽  
Slender Body Theory ◽  
Edge Angle ◽  
Finite Wing ◽  
Body Theory

Ward's slender-body theory of supersonic flow is applied to bodies terminating in either (i) a single trailing edge at right angles to the oncoming supersonic stream, or (ii) two trailing edges at right angles to one another as well as to the oncoming stream, or (iii) a cylindrical section with two or four identical fins equally spaced round it. The wave drag at zero lift, D, is given by the expression $\frac {D}{\frac {1}{2}\rho U^2} &=& \frac {1}{2\pi}\int^l_0 \int^l_0 log\frac{1}{|s-z|}S^{\prime \prime}(s)S^{\prime \prime}(z)dsdz - \\ &-& \frac{S^\prime (l)}{\pi}\int^l_0 log \frac {l}{l-z}S^{\prime \prime}(z)dz + \frac{S^{\prime 2}(l)}{2\pi} \{ log \frac{l}{(M^2-1)^{1|2}b}+k \} $ where l is the length of the body, b the semi-span of the trailing edge (or length of trailing edge of a single fin), and S(z) is the cross-sectional area of the body at a distance z behind the apex. The constant k depends on the distribution of trailing-edge angle along the span for each trailing-edge configuration. In case (i) it is 1·5 for a uniform distribution of trailing-edge angle and 1·64 for an elliptic distribution. In case (ii) it is 1·28 for a uniform distribution and 1·44 for an elliptic distribution. Study of case (iii) indicates that interference effects due to the presence of the body reduce the drag of the fins. For example, with a uniform distribution of trailing-edge angle, k for two fins falls from 1·5 in the absence of a body to 1·06 when the body radius equals the trailing-edge semi-span, while k for four fins falls from 1·28 to 0·45 under the same conditions.Where ordinary finite-wing theory is applicable, the present method must agree with it for small $(M^2-1)^{1|2}b|l$, and this is confirmed by two examples (§3), but within the limit imposed by slenderness the present method is of course more widely applicable, as well as simpler, than finite-wing theory.It is not known experimentally whether slender-body theory gives accurate predictions of drag at zero lift, for the shapes here discussed, under the conditions for which on theoretical grounds it might be expected to do so. It should be noted that, although tests have not yet been made on ideally suitable bodies, no clear the drag is therefore twice that of a wing made up of two of them. The final stages of the process cannot be represented by slender-body theory, but the initial trend may well be indicated fairly accurately.

scholarly journals On the Kutta Condition in Potential Flow over Airfoil

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Farzad Mohebbi ◽  
Mathieu Sellier
Keyword(s):  
Potential Flow ◽  
Trailing Edge ◽  
Airfoil Surface ◽  
Kutta Condition ◽  
Edge Angle ◽  
Panel Methods ◽  
Flow Potential ◽  
Novel Method ◽  
Elliptic Grid Generation ◽  
Fast Procedure

This paper proposes a novel method to implement the Kutta condition in irrotational, inviscid, incompressible flow (potential flow) over an airfoil. In contrast to common practice, this method is not based on the panel method. It is based on a finite difference scheme formulated on a boundary-fitted grid using an O-type elliptic grid generation technique. The proposed algorithm uses a novel and fast procedure to implement the Kutta condition by calculating the stream function over the airfoil surface through the derived expression for the airfoils with both finite trailing edge angle and cusped trailing edge. The results obtained show the excellent agreement with the results from analytical and panel methods thereby confirming the accuracy and correctness of the proposed method.

Biomechanical Evaluation of Syndesmotic Screw Design via Finite Element Analysis and Taguchi's Method

2015 ◽  
Vol 105 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Mehmet Serhan Er ◽  
Ozgur Verim ◽  
Mehmet Eroglu ◽  
Levent Altinel ◽  
Bariş Gokce ◽  
...  
Keyword(s):  
Finite Element ◽  
Leading Edge ◽  
Design Parameters ◽  
Outer Diameter ◽  
Trailing Edge ◽  
Screw Design ◽  
Edge Angle ◽  
Edge Radius ◽  
Thread Pitch ◽  
Inner Diameter

Background Screw fixation of syndesmotic injuries facilitates ligament healing and restoration of ankle stability, but failure of the screw might threaten the success of the treatment. Screw design parameters, such as outer diameter, inner diameter, thread pitch, leading edge radius, trailing edge radius, leading edge angle, and trailing edge angle, might have effects on the stresses that occur in the screws. This is the first study, to our knowledge, to investigate which geometric screw parameters play key roles in stresses that occur in screws used for syndesmotic fixation. Methods A three-dimensional finite element model of an ankle was reconstructed. Four different types of titanium screws—4.5-mm malleolar, 4-mm cancellous, 4-mm machine, and 3.5-mm cortical—were placed on this model. Physiologic load was applied to evaluate the stress in the screw. Then the contribution of each design factor to stress in the screws was analyzed systematically by Taguchi's robust design method. Results The maximum equivalent ductile failure (von Mises equivalent stress) value was found in the 4-mm cancellous screw (402 MPa). Taguchi's analysis showed that the descending order of contribution of the design factors to stress emerging on the screw is inner diameter, leading edge angle, thread pitch, outer diameter, and trailing edge angle. Conclusions Stress that occurs in syndesmotic screws is closely related to their geometry and dimensions. According to the results, a 3.5-mm cortical screw with the ideal screw design regarding optimal parameters to resist against stresses in the syndesmosis seems more reasonable to choose in syndesmotic fixation.

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