Numerical Calibration of Three-Dimensional Printed Five-Hole Probes for the Transonic Flow Regime

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Maximilian Passmann ◽  
Stefan aus der Wiesche ◽  
Franz Joos
Keyword(s):  
Mach Number ◽  
Flow Regime ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Number Range ◽  
Half Angle

Abstract This paper presents a method for a cost- and time-effective calibration procedure for five-hole probes for the transonic flow regime based on additive manufacturing and a numerical calibration routine. The computational setup and calibration routine are described in detail. The calibration procedure is tested on a custom-built L-shaped conical probe of 30 deg half-angle with a flat tip and an outer diameter of 2.4 mm. The probe tip is manufactured in stainless steel using direct metal laser sintering. Numerical calibration is carried out over a Mach number range of 0.2–1.4 and pitch and yaw angles of ±45 deg. The numerical calibration charts are validated with wind tunnel tests across the entire Mach number range and the expected accuracy of the numerical calibration method is quantified. Exemplary results of area traverses up- and downstream of a linear transonic turbine cascade with tip clearance are presented and discussed briefly.

Numerical Calibration of 3D Printed Five-Hole Probes for the Transonic Flow Regime

2019 ◽  
Author(s):  
Maximilian Passmann ◽  
Stefan aus der Wiesche ◽  
Franz Joos
Keyword(s):  
Flow Regime ◽  
Transonic Flow ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Number Range ◽  
Half Angle ◽  
3D Printed ◽  
Transonic Turbine

Abstract This paper presents a method for a cost- and time-effective calibration procedure for five-hole probes for the transonic flow regime based on additive manufacturing and a numerical calibration routine. The computational setup and calibration routine are described in detail. The calibration procedure is tested on a custom-built L-shaped conical probe of 30° half-angle with a flat tip and an outer diameter of 2.4mm. The probe tip is manufactured in stainless steel using DMLS. Numerical calibration is carried out over a Mach number range of 0.2 to 1.4 and pitch and yaw angles of ±45°. The numerical calibration charts are validated with wind tunnel tests and the expected accuracy of the numerical calibration method is quantified. Exemplary results of area traverses up- and downstream of a linear transonic turbine cascade with tip clearance are presented and discussed briefly.

Probe Blockage Effects in Free Jets and Closed Tunnels

1975 ◽  
Vol 97 (4) ◽  
pp. 509-514 ◽  
Author(s):  
J. S. Wyler
Keyword(s):  
Mach Number ◽  
Flow Regime ◽  
Analytical Solutions ◽  
Transonic Flow ◽  
Free Stream ◽  
Pressure Measurements ◽  
Free Jets ◽  
Blockage Effect

The effect of probe blockage on the free-stream pressure and Mach number has been studied for the two limiting cases of open free jets and closed tunnels. Cylinder probe calibrations carried out in subsonic free jets show that the blockage effect is much greater than previous analytical solutions predict. The blockage effect in free jets was found to be of approximately the same magnitude as in closed tunnels. Generalized blockage corrections are derived which indicate the importance of minimizing blockage effects both when calibrating a probe and when using it to make pressure measurements, especially in the transonic flow regime.

scholarly journals Wind Tunnel Testing on Start/Unstart Characteristics of Finite Supersonic Biplane Wing

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Hiroshi Yamashita ◽  
Naoshi Kuratani ◽  
Masahito Yonezawa ◽  
Toshihiro Ogawa ◽  
Hiroki Nagai ◽  
...  
Keyword(s):  
Mach Number ◽  
Aspect Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Wind Tunnels ◽  
Wind Tunnel Testing ◽  
Ratio Model ◽  
Number Range ◽  
Aspect Ratios ◽  
Schlieren System

This study describes the start/unstart characteristics of a finite and rectangular supersonic biplane wing. Two wing models were tested in wind tunnels with aspect ratios of 0.75 (model A) and 2.5 (model B). The models were composed of a Busemann biplane section. The tests were carried out using supersonic and transonic wind tunnels over a Mach number range of0.3≤M∞≤2.3with angles of attack of 0°, 2°, and 4°. The Schlieren system was used to observe the flow characteristics around the models. The experimental results showed that these models had start/unstart characteristics that differed from those of the Busemann biplane (two dimensional) owing to three-dimensional effects. Models A and B started at lower Mach numbers than the Busemann biplane. The characteristics also varied with aspect ratio: model A (1.3<M∞<1.5) started at a lower Mach number than model B (1.6<M∞<1.8) owing to the lower aspect ratio. Model B was located in the double solution domain for the start/unstart characteristics atM∞=1.7, and model B was in either the start or unstart state atM∞=1.7. Once the state was determined, either state was stable.

scholarly journals Calibration of Short Range 2D Laser Range Finder for 3D SLAM Usage

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Petr Olivka ◽  
Michal Krumnikl ◽  
Pavel Moravec ◽  
David Seidl
Keyword(s):  
Short Range ◽  
Three Dimensional ◽  
Ground Truth ◽  
Calibration Method ◽  
Calibration Procedure ◽  
High Angular Resolution ◽  
Laser Range Finder ◽  
Range Finder ◽  
Laser Range ◽  
Practical Applications

The laser range finder is one of the most essential sensors in the field of robotics. The laser range finder provides an accurate range measurement with high angular resolution. However, the short range scanners require an additional calibration to achieve the abovementioned accuracy. The calibration procedure described in this work provides an estimation of the internal parameters of the laser range finder without requiring any special three-dimensional targets. This work presents the use of a short range URG-04LX scanner for mapping purposes and describes its calibration. The precision of the calibration was checked in an environment with known ground truth values and the results were statistically evaluated. The benefits of the calibration are also demonstrated in the practical applications involving the segmentation of the environment. The proposed calibration method is complex and detects all major manufacturing inaccuracies. The procedure is suitable for easy integration into the current manufacturing process.

Three-Dimensional Rotational Flow in Transonic Turbomachines: Part II — Full 3D Flow in CAS Rotor Obtained by Using a Number of S1 and S2 Stream Filaments

1990 ◽  
Author(s):  
Wu Chung-Hua ◽  
Zhao Xiaolu ◽  
Qin Lisen
Keyword(s):  
Mach Number ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Flow Fields ◽  
Rotational Flow ◽  
Three Dimensional Flow ◽  
Measured Velocity ◽  
Dimensional Flow ◽  
Iterative Calculation ◽  
Good Agreement

The general theory for three–dimensional flow in subsonic and supersonic turbomachines has recently been extended to transonic turbomachines. In Part II of the paper, quasi– and full three–dimensional solutions of the transonic flow in the CAS rotor are presented. The solutions are obtained by iterative calculation between a number of S1 stream filaments and, respectively, a central S2 stream filament and a number of S2m stream filaments. Relatively simple methods developed recently for solving the transonic flow along S1 and S2 stream filaments are used in the calculation. The three–dimensional flow fields in the CAS rotor obtained by the present method are presented in detail with special emphasis on the converging process for the configuration of the S1 and S2 stream filaments. The three–dimensional flow fields obtained in the quasi– and full 3D solutions are quite similar, but the former gives a lower peak Mach number and a smaller circumferential variation in Mach number than the latter. A comparison between the theoretical solution and the Laser–2–Focus measurement shows that the character of the transonic flow including the 3D shock structure is in good agreement, but the measured velocity is slightly higher than the calculated one over most of the flow field.

scholarly journals Second sacral sacralalar‐iliac (S2AI) screw placement in adult degenerative scoliosis (ADS) patients: an imaging study

BMC Surgery ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Bing Wu ◽  
Kai Song ◽  
Junyao Cheng ◽  
Pengfei Chi ◽  
Zhaohan Wang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Imaging Study ◽  
Outer Diameter ◽  
Degenerative Scoliosis ◽  
Female Patients ◽  
Lateral Angle ◽  
Adult Degenerative Scoliosis ◽  
Imaging Characteristics ◽  
Starting Point ◽  
Trajectory Length

Abstract Background The imaging characteristics of sacral sacralalar-iliac (S2AI) screw trajectory in adult degenerative scoliosis (ADS) patients will be determined. Methods S2AI screw trajectories were mapped on three-dimensional computed tomography (3DCT) reconstructions of 40 ADS patients. The starting point, placement plane, screw template, and a circle centered at the lowest point of the ilium inner cortex were set on these images. A tangent line from the starting point to the outer diameter of the circle was selected as the axis of the screw trajectory. The related parameters in different populations were analyzed and compared. Results The trajectory length of S2AI screws in ADS patients was 12.00 ± 0.99 cm, the lateral angle was 41.24 ± 3.92°, the caudal angle was 27.73 ± 6.45°, the distance from the axis of the screw trajectory to the iliosciatic notch was 1.05 ± 0.81 cm, the distance from the axis of the screw trajectory to the upper edge of the acetabulum was 1.85 ± 0.33 cm, and the iliac width was 2.12 ± 1.65 cm. Compared with females, the lateral angle of male ADS patients was decreased, but the trajectory length was increased (P < 0.05). Compared to patients without ADS in previous studies, the lateral angle of male patients was larger, the lateral angle of female patients was increased, and the caudal angle was decreased (P < 0.05). Conclusions There is an ideal trajectory of S2AI screws in ADS patients. A different direction should be noticed in the placement of S2AI screws, especially in female patients.

scholarly journals A Study of Moist Air Condensation Characteristics in a Transonic Flow System

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4052
Author(s):  
Jie Wang ◽  
Hongfang Gu
Keyword(s):  
Mach Number ◽  
Relative Humidity ◽  
Transonic Flow ◽  
Flow System ◽  
Plane Surface ◽  
Droplet Growth ◽  
Moist Air ◽  
Dry Air ◽  
Hydraulic Equipment ◽  
Non Equilibrium

When water vapor in moist air reaches supersaturation in a transonic flow system, non-equilibrium condensation forms a large number of droplets which may adversely affect the operation of some thermal-hydraulic equipment. For a better understanding of this non-equilibrium condensing phenomenon, a numerical model is applied to analyze moist air condensation in a transonic flow system by using the theory of nucleation and droplet growth. The Benson model is adopted to correct the liquid-plane surface tension equation for realistic results. The results show that the distributions of pressure, temperature and Mach number in moist air are significantly different from those in dry air. The dry air model exaggerates the Mach number by 19% and reduces both the pressure and the temperature by 34% at the nozzle exit as compared with the moist air model. At a Laval nozzle, for example, the nucleation rate, droplet number and condensation rate increase significantly with increasing relative humidity. The results also reveal the fact that the number of condensate droplets increases rapidly when moist air reaches 60% relative humidity. These findings provide a fundamental approach to account for the effect of condensate droplet formation on moist gas in a transonic flow system.

Numerical Modeling of Heat Transfer and Pressure Losses for Uncooled Gas Turbine Blade Tip: Effect of Tip Clearance and Tip Geometry

2007 ◽  
Author(s):  
Lamyaa A. El-Gabry
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Gas Turbine ◽  
Computational Study ◽  
Numerical Models ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Pressure Losses ◽  
Blade Tip ◽  
Exit Mach Number

A computational study has been performed to predict the heat transfer distribution on the blade tip surface for a representative gas turbine first stage blade. CFD predictions of blade tip heat transfer are compared to test measurements taken in a linear cascade, when available. The blade geometry has an inlet Mach number of 0.3 and an exit Mach number of 0.75, pressure ratio of 1.5, exit Reynolds number based on axial chord of 2.57×106, and total turning of 110 deg. Three blade tip configurations were considered; they are flat tip, a full perimeter squealer, and an offset squealer where the rim is offset to the interior of the tip perimeter. These three tip geometries were modeled at three tip clearances of 1.25, 2.0, and 2.75% of blade span. The tip heat transfer results of the numerical models agree fairly well with the data and are comparable to other CFD predictions in the open literature.

Sign in / Sign up

Export Citation Format

Share Document