An Improved Aspirating Probe for Total-Temperature and Total-Pressure Measurements in Compressor Flows

1995 ◽  
Vol 117 (4) ◽  
pp. 642-649 ◽  
Author(s):  
D. E. Van Zante ◽  
K. L. Suder ◽  
A. J. Strazisar ◽  
T. H. Okiishi
Keyword(s):  
Total Pressure ◽  
High Response ◽  
Hot Wire ◽  
Time Resolved ◽  
Unsteady Temperature ◽  
Laser Anemometer ◽  
Total Temperature ◽  
Hot Wires ◽  
Response Pressure ◽  
Data Reduction Method

The aspirating probe originally designed by Epstein and Ng at MIT was modified by replacing the two platinum-coated tungsten hot wires normally used with platinum–iridium alloy wires. The resulting improved unsteady total pressure and total temperature resolution of the modified probe is demonstrated. Flowfield measurements were made downstream of NASA Rotor 37 for a part-speed operating condition to test the performance of the probe. Time-resolved blade-to-blade total temperature and total pressure as calculated from the two platinum–iridium hot-wire voltages are shown. The flowfield measurements are compared with independent measurements of total pressure with high response transducers and total temperature calculated from laser anemometer measurements. Limitations of a more often used unsteady temperature data reduction method, which involves only one aspirating probe hot-wire voltage and a high-response pressure measurement, are discussed.

An Improved Aspirating Probe for Total-Temperature and Total-Pressure Measurements in Compressor Flows

1994 ◽  
Author(s):  
Dale E. Van Zante ◽  
Kenneth L. Suder ◽  
Anthony J. Strazisar ◽  
Theodore H. Okiishi
Keyword(s):  
Total Pressure ◽  
High Response ◽  
Hot Wire ◽  
Time Resolved ◽  
Unsteady Temperature ◽  
Laser Anemometer ◽  
Total Temperature ◽  
Hot Wires ◽  
Response Pressure ◽  
Data Reduction Method

The aspirating probe originally designed by Epstein and Ng at MIT was modified by replacing the two platinum coated tungsten hot wires normally used with platinum iridium alloy wires. The resulting improved unsteady total pressure and total temperature resolution of the modified probe is demonstrated. Flowfield measurements were made downstream of NASA Rotor 37 for a part speed operating condition to test the performance of the probe. Time resolved blade-to-blade total temperature and total pressure as calculated from the two platinum iridium hot wire voltages are shown. The flowfield measurements are compared with independent measurements of total pressure with high response transducers and total temperature calculated from laser anemometer measurements. Limitations of a more often used unsteady temperature data reduction method which involves only one aspirating probe hot wire voltage and a high-response pressure measurement are discussed.

High-Frequency Effects in the Aspirating Probe

2006 ◽  
Vol 129 (4) ◽  
pp. 842-851
Author(s):  
S. J. Payne ◽  
A. J. W. Moxon
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
High Frequency ◽  
Total Pressure ◽  
Hot Wire ◽  
High Frequencies ◽  
Frequency Effects ◽  
Total Temperature ◽  
Hot Wires ◽  
High Frequency Effects

The aspirating probe has recently been successfully used to measure entropy within a turbomachine; however, it was found that its sensitivity to total pressure and total temperature fluctuations was significantly altered at high frequencies. If the aspirating probe is to be used to measure unsteady flow fields accurately, these high-frequency effects must be better understood. The analysis of this behavior presented here shows that there are three effects that must be considered: the frequency response of the hot wires, the presence of Mach number fluctuations inside the probe, and the change in heat transfer from the hot wires at high frequencies. A theoretical analysis of the first effect has provided a correction factor that can be used for any hot wire, dependent solely on the baseline heat transfer ratio, the overheat ratio, and the time constant of the hot wires. The second and third effects have been examined numerically, since no theoretical solution is known to exist. The Mach number fluctuations are found to be well predicted by a simple one-dimensional solver and to show a variation of ±2.4% in Mach number at the hot-wire plane for the geometry and flow field considered here. The variation in heat transfer with frequency is found to be negligible at high overheat ratios, but significant at overheat ratios below ∼0.4. Coefficients that determine how the measured total pressure and total temperature depend on the actual total pressure, total temperature, and Mach number have been derived, and these show significant variation with the values of the two overheat ratios. Using synthetic data, based on previous experimental data, the effects on the probe measurement accuracy are analyzed. This shows that the amplitudes of total pressure and total temperature are reduced. At widely spaced overheat ratios, the amplitudes are reduced by similar amounts, but at smaller spacing the reductions become dissimilar, resulting in highly erroneous entropy∕R measurements. High-frequency effects thus have a significant effect on the performance of the aspirating probe and should be carefully considered when using it in a highly unsteady flow field.

Flow Randomness and Tip Losses in Transonic Rotors

1993 ◽  
Author(s):  
John Alday ◽  
D. J. Osborne ◽  
Mary Beth Morris ◽  
Wing Ng ◽  
Jeff Gertz
Keyword(s):  
Total Pressure ◽  
Axial Flow ◽  
Hot Wire ◽  
Ensemble Averaging ◽  
Test Program ◽  
Time Resolved ◽  
Blade Passage ◽  
Total Temperature ◽  
Overall Efficiency ◽  
Isentropic Efficiency

The results of a test program incorporating a dual hot-wire aspirating probe to radially survey the exit flowfields of two axial-flow transonic fans are presented. The probe measures time-resolved total temperature and total pressure, from which the instantaneous isentropic efficiency is calculated. A technique for quantifying the randomness in an unsteady turbomachine flowfield is developed. Randomness is quantified by blade wake aperiodicity (variation of blade passage period) and non-uniformity (variation of blade wake shape). A method of ensemble averaging instantaneous data is presented which produces an identifiable blade passage wake profile even in a random flowfield where traditional techniques often fail. The flowfield randomness for the two fans is shown to correlate well with the respective tip losses. Results also show that the overall efficiency of the best blade on a fan rotor can be 0.5% higher than the performance of the rotor overall average or as much as 0.7% higher than the worst blade on the rotor.

Detailed Experimental Measurement and RANS Simulation of a Low Pressure Turbine With High Lift Blading

2019 ◽  
Author(s):  
Ethan Perez ◽  
John T. Schmitz ◽  
Nicholas A. Jaffa ◽  
Aleksandar Jemcov ◽  
Joshua D. Cameron ◽  
...  
Keyword(s):  
Total Pressure ◽  
Low Pressure ◽  
Aerodynamic Characteristics ◽  
Expansion Ratio ◽  
High Lift ◽  
Time Resolved ◽  
Low Pressure Turbine ◽  
Hot Wires ◽  
Simulation Results ◽  
Improved Performance

Abstract The aerodynamic characteristics of high–lift airfoil designs is of interest for improved performance and reduced blade count in Low–Pressure Turbine (LPT) design. The present paper presents both experimental measurements as well as numerical simulation results from a single-stage LPT. The airfoils were designed for an embedded stage with a total pressure expansion ratio of 1.75 and a rotor Zweifel coefficient of 1.35. The measurement program was highly unique in that detailed measurements were obtained using a variety of different probe types, including time–resolved total pressure and hot–wires. Agreement between various measurement types was generally good, but differences beyond typically stated uncertainty bounds were noted. The computations were done using RANS and a mixing model via commercially available software. The numerical results were evaluated to determine the efficacy of this type of model for prediction and design of high–lift airfoils. The computations agreed very well with the experimental results in the midspan region, but losses were over–predicted in the lower 40% span near the hub. A basic description and understanding of the flow physics in the LPT stage are presented based on the relative agreement between the experiments and computations.

scholarly journals Design of an Economical Counter Rotating Fan: Comparison of the Calculated and Measured Steady and Unsteady Results

2012 ◽  
Author(s):  
Timea Lengyel-Kampmann ◽  
Andreas Bischoff ◽  
Robert Meyer ◽  
Eberhard Nicke
Keyword(s):  
High Resolution ◽  
Total Pressure ◽  
High Efficiency ◽  
Optimization Method ◽  
Test Facility ◽  
Hot Wire ◽  
Stall Margin ◽  
Low Speed ◽  
Total Temperature ◽  
German Aerospace

Within the framework of the EU funded Project VITAL, SNECMA (Group Safran), as the work package leader, developed a counter rotating low-speed fan-concept for a high bypass ratio engine. The detailed aerodynamic and mechanical optimization of one blading version (CRTF2.b) was carried out at the German Aerospace Center (DLR), by applying one of the newest design methods featuring a multi-objective automatic optimization method based on an Evolutionary Algorithm [1]. The final design goals were high efficiency, a sufficient stall margin and adequate acoustic performances for the given cycle parameters. The fan stage developed was tested in an anechoic test facility at CIAM in Moscow. The test routine included the measurement of the performance map based on total pressure and total temperature measurements at the inlet and the outlet of the test rig and acoustic measurement as well. The unsteady flow field of the low speed Contra-Rotating Turbo Fan has been measured with four hot-wire probes at different axial positions. In the evaluation the measured data are compared with high resolution CFD results. Special emphasis was given to the comparison of the radial distribution of total pressure and total temperature in the bypass channel, the comparison of the measured and the calculated fan maps and to the comparison of the hot-wire measurements with high resolution, unsteady CFD results. The tests and the URANS-results confirmed the design goals.

Unsteady Three-Dimensional Analysis of Inlet Distortion in a Transonic Fan

2006 ◽  
Author(s):  
Peng Sun ◽  
Guotal Feng
Keyword(s):  
Shock Wave ◽  
Total Pressure ◽  
Large Scale ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Inlet Distortion ◽  
Flow Loss ◽  
Large Scale Vortex ◽  
Total Temperature ◽  
Transonic Fan

A time-accurate three-dimensional Navier-Stokes solver of the unsteady flow field in a transonic fan was carried out using "Fluent-parallel" in a parallel supercomputer. The numerical simulation focused on a transonic fan with inlet square wave total pressure distortion and the analysis of result consisted of three aspects. The first was about inlet parameters redistribution and outlet total temperature distortion induced by inlet total pressure distortion. The pattern and causation of flow loss caused by pressure distortion in rotor were analyzed secondly. It was found that the influence of distortion was different at different radial positions. In hub area, transportation-loss and mixing-loss were the main loss patterns. Distortion not only complicated them but enhanced them. Especially in stator, inlet total pressure distortion induced large-scale vortex, which produced backflow and increased the loss. While in casing area, distortion changed the format of shock wave and increased the shock loss. Finally, the format of shock wave and the hysteresis of rotor to distortion were analyzed in detail.

A Fiber Optic Probe for Gas Total Temperature Measurement in Turbomachinery

1995 ◽  
Vol 117 (4) ◽  
pp. 635-641 ◽  
Author(s):  
S. R. Kidd ◽  
J. S. Barton ◽  
P. Meredith ◽  
J. D. C. Jones ◽  
M. A. Cherrett ◽  
...  
Keyword(s):  
Fiber Optics ◽  
High Speed ◽  
Gas Temperature ◽  
Fiber Optic Probe ◽  
Sensing Element ◽  
Unsteady Temperature ◽  
High Bandwidth ◽  
New Type ◽  
Total Temperature ◽  
Optic Probe

This paper describes the design, operation, construction, and demonstration of a new type of high-bandwidth unsteady temperature sensor based on fiber optics, and capable of operating in a high-speed multistage research compressor with flow representative of jet engine conditions. The sensing element is an optical coating of zinc selenide deposited on the end of an optical fiber. During evaluation in aerodynamic testing, a 1 K gas temperature resolution was demonstrated at 9.6 kHz and an upper bandwidth limit of 36 kHz achieved.

scholarly journals Grid Dependency Study for the NASA Rotor 37 Compressor Blade

1997 ◽  
Author(s):  
Andrea Arnone ◽  
Ennio Carnevale ◽  
Michele Marconcini
Keyword(s):  
Total Pressure ◽  
Turbulence Modeling ◽  
Leading Edge ◽  
Substantial Improvement ◽  
Compressor Blade ◽  
Computational Domain ◽  
Temperature Ratio ◽  
Turbulent Transition ◽  
Total Temperature ◽  
The Impact

The NASA Rotor 37 has been computed by several authors in the last few years with relative success. The aim of this work is to present a systematic grid dependency study in order to quantify the amount of uncertainty that comes from the grid density. The computational domain is divided onto several regions (i.e. leading edge, trailing edge, shear layer …) and for each of them, the impact of the grid density is investigated. By means of this analysis, substantial improvement has been obtained in the prediction of efficiency and exit angle. On the contrary, the improvement achieved in total pressure and total temperature ratio is less remarkable. It is believed that only after a systematic grid dependency study can the contribution of turbulence modeling, laminar-turbulent transition, and boundary conditions be analyzed with success.

Influence of Backward- and Forward-Facing Steps on the Flow Through a Turning Mid Turbine Frame

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Sabine Bauinger ◽  
Emil Goettlich ◽  
Franz Heitmeir ◽  
Franz Malzacher
Keyword(s):  
High Pressure ◽  
Total Pressure ◽  
Test Rig ◽  
Test Setup ◽  
Aero Engine ◽  
Total Temperature ◽  
Flow Through ◽  
Run Up ◽  
Compact Design ◽  
Probe Measurements

For this work, reality effects, more precisely backward-facing steps (BFSs) and forward-facing steps (FFSs), and their influence on the flow through a two-stage two-spool turbine rig under engine-relevant conditions were experimentally investigated. The test rig consists of an high pressure (HP) and an low pressure (LP) stage, with the two rotors rotating in opposite direction with two different rotational speeds. An S-shaped transition duct, which is equipped with turning struts (so-called turning mid turbine frame (TMTF)) and making therefore a LP stator redundant, connects both stages and leads the flow from a smaller to a larger diameter. This test setup allows the investigation of a TMTF deformation, which occurs in a real aero-engine due to non-uniform warming of the duct during operation—especially during run up—and causes BFSs and FFSs in the flow path. This happens for nonsegmented ducts, which are predominantly part of smaller engines. In the case of the test rig, steps were not generated by varying temperature but by shifting the TMTF in horizontal direction while the rotor and its casing were kept in the same position. In this way, both BFSs and FFSs between duct endwalls and rotor casing could be created. In order to avoid steps further downstream of the interface between HP rotor and TMTF, the complete aft rig was moved laterally too. In this case, the aft rig incorporates among others the LP rotor, the LP rotor casing, and the deswirler downstream of the LP stage. In order to catch the influence of the steps on the whole flow field, 360 deg rake traverses were performed downstream of the HP rotor, downstream of the duct, and downstream of the LP rotor with newly designed, laser-sintered combi-rakes for the measurement of total pressure and total temperature. Only the compact design of the rakes, which can be easily realized by additive manufacturing, makes the aforementioned 360 deg traverses in this test rig possible and allows a number of radial measurements positions, which is comparable to those of a five-hole probe. To get a more detailed information about the flow, also five-hole probe measurements were carried out in three measurement planes and compared to the results of the combi-rakes.

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