Flow Angle Measurements Research Articles

Study on Matrix Damage and Control Methods of Fracturing Fluid on Tight Sandstone Gas Reservoirs.

Hydraulic fracturing is a highly effective method for stimulating the development of gas reservoirs. However, the process of pumping fracturing fluid (FF) into the reservoir unavoidably causes damage to the surrounding matrix, leading to a decrease in the overall stimulation effect. To assess the extent of matrix permeability damage caused by the intrusion of FF, as well as its impact on the pore throat structure, and to propose appropriate measures to control this damage, we conducted a series of experimental studies on tight gas reservoirs. These studies included mercury intrusion, core flow, nitrogen adsorption, linear expansion, and contact angle measurements. The findings revealed that the damage inflicted on matrix permeability by FF was significantly greater than that caused by its gel-breaking counterpart. Surprisingly, the damage rate of the rejecting fluid to the matrix was found to be comparable to that of its gel-breaking counterpart. The fractal dimension (D2) was observed to have a strong correlation with surface area, pore volume, and mean pore size, making it an effective means of characterizing pore structure characteristics. After the rock samples were displaced by the formation water, the D2 value decreased, leading to a decrease in the complexity of the pore throat structure and an increase in matrix permeability. Conversely, the displacement of the FF increased the D2 value, indicating a gradual complication of the pore throat structure and a more uneven distribution of pore sizes. The inclusion of polyamide in antiexpansion FF, as well as its gel-breaking counterpart, proved to be effective in inhibiting the hydration and expansion of clay minerals, thereby reducing water-sensitive damage. Additionally, the use of surfactants with low surface tension enhanced the flowback rate of FF by increasing the contact angle and reducing the work of adhesion. This, in turn, helped to decrease the apparent water film thickness and expand gas flow channels, ultimately improving gas permeability.

A flow field around a cylindrical probe in proximity to stator blades and its effect on the measurements

In multistage axial compressors of gas turbine engines, there is a need for a detailed understanding of the flow field in between the blade rows, which could be obtained by spanwise traversing. This requires a pneumatic probe to be immersed into the flow path between the blade rows, where the space is limited. Therefore, the probe will affect the flow field around it and in the blade channel, and the probe readings will be affected by that flow field. As a result, these probe readings cannot be translated to flow parameters based on just the freestream calibration characteristics, obtained in the idealized wind tunnel. In our paper, we provide a computational analysis of the flow field around the cylindrical probe in a constrained inter-blade-row environment at different circumferential locations and flow conditions both upstream and downstream of the stator blade row. It is shown that the flow angle measurement error can reach up to five degrees in the mid-pitch locations compared to undistorted flow, and dynamic head measurements can be up to 30% away from the actual mean values of the flow. These deviations are shown to be caused by flow field interaction inside the blade channel and, as a result, measured values, obtained during industrial compressor testing, could be corrected accordingly. The universal correction procedure is proposed for further use in the industry

유속 및 각도 측정을 위한 인공 옆줄 센서 개발

유속 및 각도 측정을 위한 인공 옆줄 센서 개발

Design and Evaluation of UAV Flow Angle Estimation Filters

This paper presents the design, implementation, and evaluation of four filters for the estimation of angle of attack (AOA) and angle of sideslip (AOS) of small unmanned aerial vehicles (UAVs). Specifically, two novel filters (a complementary filter and an extended Kalman filter) are proposed and evaluated without using direct flow angle and Global Positioning System measurements; two existing AOA/AOS filters are also implemented and evaluated. All filters are designed with minimal inputs and states to ensure the ease of implementation, simplicity of tuning, and computation efficiency. Both simulation and UAV flight test results show the performance of the proposed filters. Especially, flight test results from two different UAVs (a T-tail UAV and a flying wing UAV) show that the root mean square errors of estimated inertial AOA and AOS are less than 1.5 $^\circ$ under nominal flight conditions and around 2 $^\circ$ under aggressive maneuvers compared with direct flow angle measurements.

Rapid measurement of transversal flow velocity vector with high spatial resolution using speckle decorrelation optical coherence tomography.

We propose and demonstrate a novel method that uses only three sets of B-scans to accurately determine both the direction and the speed of a transversal flow using speckle decorrelation optical coherence tomography. Our tri-scan method has the advantages of high measurement speed, high spatial resolution, and insensitivity to the flow speed. By introducing error maps, we show that the flow angle inaccuracy can be minimized by choosing the measurement result with a lesser error between results obtained from the x- and y-scans. Finally, we demonstrate that the flow angle measurement accuracy can be further improved for the high-speed flows by increasing the speed of the x- and y-scans.

An innovative method to calibrate a spinner anemometer without the use of yaw position sensor

Abstract. A spinner anemometer can be used to measure the yaw misalignment and flow inclination experienced by a wind turbine. Previous calibration methods used to calibrate a spinner anemometer for flow angle measurements were based on measurements of a spinner anemometer with default settings (arbitrary values, generally k1,d = 1 and k2,d = 1) and a reference yaw misalignment signal measured with a yaw position sensor. The yaw position sensor is normally present in wind turbines for control purposes; however, such a signal is not always available for a spinner anemometer calibration. Therefore, an additional yaw position sensor was installed prior to the spinner anemometer calibration. An innovative method to calibrate the spinner anemometer without a yaw positions sensor was then developed. It was noted that a non-calibrated spinner anemometer that overestimates (underestimates) the inflow angle will also overestimate (underestimate) the wind speed when there is a yaw misalignment. The new method leverages the non-linearity of the spinner anemometer algorithm to find the calibration factor Fα by an optimization process that minimizes the dependency of the wind speed on the yaw misalignment. The new calibration method was found to be rather robust, with Fα values within ±2.7 % of the mean value for four successive tests at the same rotor position.

Effects of prong-wire interferences in dual hot-wire probes on the measurements of unsteady flows and turbulence in low-speed axial fans

Support needles of Dual Hot Wire (DHW) anemometers induce significant inaccuracies for flow angle and turbulence measurements in the case of X-array probes with prongs perpendicular to the flow plane. At certain angular ranges of the incident flow, a wake interference is established between the sensors which leads to a practical limitation of the device. In the case of turbomachinery environments, this is even more critical due to the inherent unsteadiness of the flow direction rotor downstream.In the present work, the measurement deviation caused by hot-wire probes operated under interference effects has been studied and evaluated, in both steady and unsteady conditions, especially for turbomachinery flows. New designs of DHW probes without prong-wire interference effects in their operative angular ranges were developed for validation. In particular, both V-type and Z-type interference-free probes are compared to a classic X-type probe susceptible for prong-wire interferences. Firstly, a steady calibration is performed to show the baseline deviation of the X-array probe in the measurement of the velocity magnitude, the flow angle and the turbulence intensity. Typical errors up to 10–13% in velocity, 5.5–7deg in angle and 1.5–2.5 points overestimation in turbulence levels are observed. Also, unacceptable inaccuracies are found in the turbulence spectra of the measurements.Following, the impact of the interference for unsteady flow measurements is highlighted comparing the performance of the three probes within the single stage of a low-speed axial fan. The unsteady measurements of the X-array probe have revealed similar averaged discrepancies to those observed in the steady performance, but the instantaneous deviations can be as high as a 20% in velocity and 16–18deg in flow angle in those regions (rotor wakes) with large unsteady velocity gradients and turbulence generation. Turbulence intensity measured in the rotor wakes is also excessively higher.

Frequency-Domain Method for Automated Simulation Updates Based on Flight Data

A statistically based frequency-domain method for using flight data to update aerodynamic data tables used in flight simulators is developed and demonstrated. The capability to accurately and automatically update a simulation to incorporate nonlinear and unsteady aerodynamic effects embodied in the flight data is demonstrated. Useful features of this novel frequency-domain approach are highlighted, including computational efficiency, noise rejection, automated model structure determination in the frequency domain for nonlinear and unsteady aerodynamics, and the ability to generate simulation updates without air flow angle measurements in the flight data. An F-16 nonlinear simulation is used to demonstrate the technique.

Microfabrication of a variable range and multi-directionally sensitive thermal flow sensor

This investigation reports the design, fabrication and characterization of a variable range and multi-directionally sensitive micromachined thermal flow sensor based on amorphous germanium thermistors. For measuring various flow ranges and flow directions with a single device, 12 thermistors are placed on an 2mm×2mm supporting square shaped dielectric membrane made with silicon nitride. The thermistors are located at different optimized distances from a central micro-heater that is made with a bilayer of Ti/Pt and can be heated to 200°C with about 580mW applied power. The thermistors are laid as six pairs on the aforementioned substrate with three pairs located along the X-axis and another three pairs located along the Y-axis. The device was characterized in the presence of air flow velocities up to 20m/s and at constant heating power modes of 500mW and 250mW in order to measure the achievable flow speed and direction. Characterization results were compared with simulation results and the errors in flow speed and angle measurement have been discussed.

Unsteady Vane Boundary Layer Response to Rotor–Rotor Interactions in a Multistage Compressor

Experiments have been performed in a three-stage axial compressor to investigate unsteady stator boundary-layer transition in an embedded stage environment. Quasi-wall shear stress data have been acquired on the suction surface of the second stage stator, in addition to unsteady flow angle measurements at the stator inlet. With two rotor blade rows upstream of the instrumented stator, blade row interactions representative of a multistage environment are present. The different blade counts for the upstream rotors provide an unsteady flowfield at the stator inlet featuring a beating pattern. There is no portion of fully laminar boundary-layer flow on this vane. The vane boundary layer is transitional near the leading edge, and transition to a fully turbulent boundary layer is complete by 45% suction side length. The presence of the rotor 1 wakes, when arriving in between the rotor 2 wakes, increases the normalized quasi-wall shear stress in the leading-edge region by 4% and decreases the amount of laminar transitional flow.

Experimental Study of the Instationary Flow Between Two Ducted Counter-Rotating Rotors

The purpose of this work is to study experimentally the aerodynamic characteristics of a subsonic counter-rotating axial-flow fans system operating in a ducted configuration. The fans of diameter D=375 mm were designed to match the specification point using an original iterative method: the front rotor blade cascade is designed with a conventional inverse method, setting the radial distribution of the Euler work. The through-flow is then computed using an axisymmetric and radial equilibrium assumption, with empirical models of losses. The rear rotor is not conventional but is designed to straighten the radial profile of the tangential velocity. The design of the front rotor is then modified until the stage meets the requirements. The experimental setup is arranged such that the rotation rate of each fan is independently controlled and that the axial distance between the rotors can be varied from 17% to 310% of the midspan chord length. Systematic measurements of the global performances and local measurements of the velocity field and of the wall pressure fluctuations are performed, in order to first validate the design method, and to explore the effects of the two specific free parameters of the system, the axial spacing and the ratio of rotation rates. The results show that the efficiency is strongly increased compared to a conventional rotor or to a rotor-stator stage. The developed design method slightly overpredicts the pressure rise and slightly underpredicts the best ratio of rotation rates. Flow angle measurements downstream of the stage show that the outflow is not completely straightened at the design point. Finally, the system is highly efficient on a wide range of flow rates and pressure rises: this system has thus a very flexible use, with a large patch of high efficient operating points in the parameter space.

Real-Time Aerodynamic Parameter Estimation Without Air Flow Angle Measurements

A technique for estimating aerodynamic parameters in real time from flight data without air flow angle measurements is described and demonstrated. The method is applied to simulated F-16 data, and to flight data from a subscale jet transport aircraft. Modeling results obtained with the new approach using flight data without air flow angle measurements were compared to modeling results computed conventionally using flight data that included air flow angle measurements. Comparisons demonstrated that the new technique can provide accurate aerodynamic modeling results without air flow angle measurements, which are often difficult and expensive to obtain. Implications for efficient flight testing and flight safety are discussed.

Numerical Study of Flow Angles and Mach Number Measurement Using the Surface Pressure of a Supersonic Aircraft with Nose Cone

Numerical simulation of the flow around an air data sensor (ADS), which measures flow angles and Mach numbers using surface pressures on a nose cone, was conducted in this study. Effects of the half-cone angle on the flow angle and Mach number measurements were investigated. Results show that a large half-cone angle achieves high sensitivity of flow angle measurements. Results further demonstrated that a small half-cone angle achieves high-sensitivity of Mach number measurements. To satisfy these conflicting requests, we proposed the use of bi-conic nose cones with two gradients. High sensitivity was achieved for both flow angle measurements and Mach number measurements using this bi-conic nose cone.

ノーズコーンをもつ超音速機の壁面圧力を用いた機体姿勢およびマッハ数計測に関する数値解析

Numerical simulation on the Air Data Sensor System (ADS), which measures the flow angles and Mach number using the surface pressures on a nose cone, was conducted in this study. The effect of the half cone angle on the flow angle and Mach number measurement was investigated. As a result, we found that a large half cone angle achieves a high sensitivity at the flow angle measurement. It was also found that a small half cone angle achieves a high sensitivity at the Mach number measurement. To satisfy these conflicting requests, we proposed a new shape nose cone which has two different gradients. The high sensitivity was achieved at both the flow angle measurement and Mach number measurement by this new shape nose cone.

In‐channel atom‐transfer radical polymerization of thermoset polyester microfluidic devices for bioanalytical applications

A new technique for polymer microchannel surface modification, called in-channel atom-transfer radical polymerization, has been developed and applied in the surface derivatization of thermoset polyester (TPE) microdevices with poly(ethylene glycol) (PEG). X-ray photoelectron spectroscopy, electroosmotic flow (EOF), and contact angle measurements indicate that PEG has been grafted on the TPE surface. Moreover, PEG-modified microchannels have much lower and more pH-stable EOF, more hydrophilic surfaces and reduced nonspecific protein adsorption. Capillary electrophoresis separation of amino acid and peptide mixtures in these PEG-modified TPE microchips had good reproducibility. Phosducin-like protein and phosphorylated phosducin-like protein were also separated to measure the phosphorylation efficiency. Our results indicate that PEG-grafted TPE microchips have broad potential application in biomolecular analysis.

Effects of upstream installations on the reading of an ultrasonic flowmeter

The downstream flow of two typical installations in piping systems, the 90° bend and the double bend, is experimentally identified by flow angle measurements at the pipe wall. The identified downstream flow patterns are stable when the installation inflow is stabilized. An ultrasonic flowmeter is exposed to the downstream flow at various positions and circumferential angles. At each position the error shift of the flowmeter is recorded. A unique assignment between flow pattern and error shift is found paving the way for an intelligent correction of flowmeters.

Caractéristique directionnelle calculée et mesurée d'une sonde électrochimique

The present paper demonstrates how the directional characteristics of an actual three-segment electrodiffusional sensor can be calculated from the probe image. It was shown that utilization of ‘ideal’ directional characteristics lead to an important (up to 15 ∘) error in flow angle determination. The directional characteristics calculated from the probe image improve significantly (up to 50%) the accuracy of the flow angle measurements. To cite this article: F. Barbeu et al., C. R. Mecanique 330 (2002) 433–436.

Investigation of the direction of chip motion in diamond turning

Management of the chips generated in diamond turning is often critical since contact between chips and the workpiece can result in superficial damage to the finished surface. Controlling chip motion is not a trivial process as the proper positioning of an oil or an air stream requires an understanding of the dynamics of a diamond turned chip and the machining parameters that affect it. Previous work [1] introduced the chip curvature parameter, χ, which is useful in predicting chip radius of curvature over a wide range of cutting speeds, depths of cut, tool geometries and workpiece material properties. To control chip motion, however, an understanding of the direction chips leave the tool/workpiece interface must also be obtained. Cutting experiments were performed investigating the influence of cutting speed, depth of cut, feed rate, tool path angle, tool geometry and tool orientation on the directional characteristics of the motion of diamond turned chips. Flow angle measurements obtained during cutting were found to remain within ± 10° of predictions from a simple geometrical model originally proposed for conventional machining.

Steady-unsteady measurements of the flow field downstream of a transonic high-pressure turbine stage

The three-dimensional flow field of a transonic high-pressure turbine stage has been studied experimentally in the von Karman Institute short duration compression tube facility. The test programme encompasses two Reynolds numbers ( Re2, c = 1.0 × 106, 1.26 × 106) and three different pressure ratios ( Po1/ Ps3 = 2.3, 3.1, 4.1). The steady flow angle, pressure and temperature measurements rely on five-hole pneumatic probes and micro-thermocouples. Fast response pressure and cold wire resistance thermometer probes measure the unsteady pressure and temperature. The experimental time-averaged spanwise distributions are compared with steady state three-dimensional Navier-Stokes stage simulations; zones of secondary flows are identified in the spanwise distributions. The stage exit pitchwise traverses show that the stator exit flow field affects the stage exit flow. Downstream of the stator vane, large time-resolved static pressure fluctuations are identified, attributed to the variation of the origin, the incidence and strength of the stator trailing edge shock. At the stage outlet, large total temperature fluctuations appear owing to the periodic passage of the tip leakage flow. For the high-pressure ratio, the rotor is choked and large pressure and temperature fluctuations are recorded owing to the rotating rotor trailing edge shock system. Zones of high mixing (secondary flows) tend to attenuate these fluctuations.

Experimental audit of the mixing-plane approach to turbomachinery analysis and a review of alternative multi-row techniques

AbstractDetailed numerical comparisons of pressure and flow angle measurements made in stage three of a four-stage, large scale, low speed, axial compressor are presented. The measurements are in both the rotating and stationary frame and were obtained as part of a BRITE/EURAM collaborative study of cantilevered and shrouded-stator compressor configurations. The numerical analysis is 3D, considers three blade rows simultaneously and incorporates multiple row effects by use of a conservative mixing-plane model allowing circumferential variation at the mixing plane.The paper discusses the early results of a study sponsored by Alstom Gas Turbines to examine steady-state, multiple blade-row modelling techniques. Growth in the endwall flow region due to multi-row effects is revealed from both the numerical and experimental results. The numerical simulation is conducted without altering blade gap spacings to assist numerical stability; the axial gap is increasingly being seen as a critical performance parameter for multiple row analysis. The limitations inherent in an approach using mixing-planes are presented and a review of alternative, more rigourous, treatments of these effects is then discussed. These treatments attempt to retain the unsteady flow structure in a steady-state model by the derivation of so-called deterministic stresses.