High-temperature high-frequency turbine exit flow field measurements in a military engine with a cooled unsteady total pressure probe

Author(s):  
M Mersinligil ◽  
J Desset ◽  
J F Brouckaert

The measurement of unsteady pressures within the hot components of gas turbine engines still remains a true challenge for test engineers. Several high-temperature pressure sensors have been developed, but so far, their applications are restricted to unsteady wall static pressure measurements. Because of the severe flow conditions such as turbine inlet temperatures of 1700 °C and pressures of 50 bar or more in the most advanced aero-engine designs, few (if any) experimental techniques exist to measure the time-resolved flow total pressure inside the gas path. This article describes the measurements performed at the turbine exit of a military engine with a cooled fast response total pressure probe. The probe concept is based on the use of a conventional miniature piezo-resistive pressure sensor, located in the probe tip to achieve a bandwidth of at least 40 kHz. Due to the extremely harsh conditions, the probe and sensor are heavily water cooled. The probe was designed to be continuously immersed into the hot gas stream to obtain time series of pressure with a high bandwidth and therefore statistically representative average fluctuations at the blade passing frequency (BPV). The experimental results obtained with a second-generation prototype are presented. The probe was immersed into the engine through the bypass duct between turbine exit and flame-holders of the afterburner of a Volvo RM12 engine, at exhaust temperatures above 900 °C. The probe was able to resolve the BPV (∼17 kHz) and several harmonics up to 100 kHz.

Author(s):  
Mehmet Mersinligil ◽  
Jean-Franc¸ois Brouckaert ◽  
Nicolas Courtiade ◽  
Xavier Ottavy

Over the last decades, fast response aerodynamic probes have been recognized as a robust measurement technique to provide time-resolved flow field data in turbomachinery environments. Still, most of the existing probe designs are restricted to low temperature applications (< 120 °C) either because of sensor temperature range limitations or packaging issues. Measurements in turbomachines also require a small probe size often with a very high bandwidth which are conflictual constraints difficult to satisfy simultaneously. This contribution therefore presents the development of a novel miniature (O̸ 2.5 mm) high temperature single sensor total pressure probe, designed for operation up to 250 °C with a very high bandwidth of 250 kHz. The probe main element is a 1.7 mm diameter commercial piezoresistive transducer placed in a Pitot type arrangement with a flush mounted sensor to provide the highest bandwidth. The details of the probe design are presented as well as the probe calibrations in pressure and in temperature. The effects of using a thermal compensation module or a sense resistor to monitor the temperature drift are described in the context of measurement uncertainty. The probes were characterized in terms of aerodynamic characteristics versus flow angle and Mach number. Shock tube tests have shown a dynamic response of the probe with sensor resonance frequencies well over 300 kHz, with a flat frequency range up to 250 kHz. Two probe prototypes were manufactured and first used in the 3 1/2-stage high speed axial compressor CREATE of the LMFA at E´cole Centrale de Lyon in France. The probes were traversed at each inter blade row plane up to temperatures of 180 °C and absolute pressure of 3 bar. The probe was able to resolve the high blade passing frequencies (∼16 kHz) and several harmonics including rotor-stator interaction frequencies up to 200 kHz. Besides the average total pressure distributions from the radial traverses, phase-locked averages and random unsteadiness are presented. The probe spatial and temporal resolutions are discussed in the context of those results.


Author(s):  
Mehmet Mersinligil ◽  
Jean-François Brouckaert ◽  
Nicolas Courtiade ◽  
Xavier Ottavy

Over the last decades, fast response aerodynamic probes have been recognized as a robust measurement technique to provide time-resolved flow field data in turbomachinery environments. Still, most of the existing probe designs are restricted to low temperature applications (<120 °C) either because of sensor temperature range limitations or packaging issues. Measurements in turbomachines also require a small probe size often with a very high bandwidth which are conflicting constraints difficult to satisfy simultaneously. This contribution therefore presents the development of a novel miniature (∅ 2.5 mm ) high temperature single sensor total pressure probe, designed for operation up to 250 °C with a very high bandwidth of 250 kHz. The probe main element is a 1.7 mm diameter commercial piezoresistive transducer placed in a Pitot type arrangement with a flush mounted sensor to provide the highest bandwidth. The details of the probe design are presented as well as the probe calibrations in pressure and in temperature. The effects of using a thermal compensation module or a sense resistor to monitor the temperature drift are described in the context of measurement uncertainty. The probes were characterized in terms of aerodynamic characteristics versus flow angle and Mach number. Shock tube tests have shown a dynamic response of the probe with sensor resonance frequencies well over 300 kHz, with a flat frequency range up to 250 kHz. Two probe prototypes were manufactured and first used in the 3½-stage high speed axial compressor CREATE of the LMFA at École Centrale de Lyon in France. The probes were traversed at each interblade row plane up to temperatures of 180 °C and absolute pressure of 3 bars. The probe was able to resolve the high blade passing frequencies (∼16 kHz) and several harmonics including rotor-stator interaction frequencies up to 200 kHz. Besides the average total pressure distributions from the radial traverses, phase-locked averages and random unsteadiness are presented. The probe spatial and temporal resolutions are discussed in the context of those results.


2021 ◽  
Vol 62 (2) ◽  
Author(s):  
Florian M. Heckmeier ◽  
Stefan Hayböck ◽  
Christian Breitsamter

Abstract The spatial and temporal resolution of a fast-response aerodynamic pressure probe (FRAP) is investigated in a benchmark flow of grid-generated turbulence. A grid with a mesh size of $$M=6.4$$ M = 6.4 mm is tested for two different free-stream velocities, hence, resulting in Reynolds numbers of $$Re_M= \{4300,12800\}$$ R e M = { 4300 , 12800 } . A thorough analysis of the applicability of the underlying assumptions with regard to turbulence isotropy and homogeneity is carried out. Taylor’s frozen turbulence hypothesis is assumed for the calculation of deducible flow quantities, like the turbulent kinetic energy or the dissipation rate. Furthermore, besides the examination of statistical quantities, velocity spectra of measurements downstream of the grid are quantified. Results of a small fast-response five-hole pressure probe equipped with piezo-resistive differential pressure sensors are compared to single-wire hot-wire constant temperature anemometry data for two different wire lengths. Estimates of temporal and spatial turbulent scales (e.g., Taylor micro scale and Kolmogorov length scale) show good agreement to data in the literature but are affected by filtering effects. Especially in the energy spectra, very high bandwidth content cannot be resolved by the FRAP, which is mainly due to bandwidth limits in the temporal calibration of the FRAP and the minimal resolution of the integrated sensors. Graphic abstract


Author(s):  
Jean-François Brouckaert ◽  
Mehmet Mersinligil ◽  
Marco Pau

The present paper proposes a concept for a water-cooled high temperature unsteady total pressure probe intended for measurements in the hot sections of industrial gas turbines or aero-engines. This concept is based on the use of a conventional miniature piezoresistive pressure sensor, which is located at the probe tip to achieve a bandwidth of at least 40 kHz. Due to extremely harsh conditions and the intention to immerse the probe continuously into the hot gas stream, the probe and sensor must be heavily cooled. The short term objective of this design is to gain the capability of performing measurements at the temperature conditions typically found at high pressure turbine exit (1100–1400 K) and in the long term at combustor exit (2000 K or higher).


Author(s):  
Jean-Franc¸ois Brouckaert ◽  
Mehmet Mersinligil ◽  
Marco Pau

The present paper proposes a concept for a water cooled high temperature unsteady total pressure probe, intended for measurements in the hot sections of industrial gas turbines or aero-engines. This concept is based on the use of a conventional miniature piezo-resistive pressure sensor, located at the probe tip to achieve a bandwidth of at least 40kHz. Due to extremely harsh conditions and the intention to immerse the probe continuously into the hot gas stream, the probe and sensor must be heavily cooled. The short term objective of this design is to gain the capability of performing measurements at the temperature conditions typically found at high pressure turbine exit (1100–1400K) and in the long term at combustor exit (2000K or higher).


Alloy Digest ◽  
1999 ◽  
Vol 48 (7) ◽  

Abstract Haynes alloy 75 is an 80 nickel-20 chromium alloy with both good oxidation resistance and good mechanical properties at high temperatures. It is amenable to all forms of fabrication and welding. A typical application for sheet metal is fabrications in gas turbine engines. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming and heat treating. Filing Code: Ni-557. Producer or source: Haynes International Inc.


2009 ◽  
Vol 132 (1) ◽  
Author(s):  
O. Schennach ◽  
J. Woisetschläger ◽  
B. Paradiso ◽  
G. Persico ◽  
P. Gaetani

This paper presents an experimental investigation of the flow field in a high-pressure transonic turbine with a downstream vane row (1.5 stage machine) concerning the airfoil indexing. The objective is a detailed analysis of the three-dimensional aerodynamics of the second vane for different clocking positions. To give an overview of the time-averaged flow field, five-hole probe measurements were performed upstream and downstream of the second stator. Furthermore in these planes additional unsteady measurements were carried out with laser Doppler velocimetry in order to record rotor phase-resolved velocity, flow angle, and turbulence distributions at two different clocking positions. In the planes upstream of the second vane, the time-resolved pressure field has been measured by means of a fast response aerodynamic pressure probe. This paper shows that the secondary flows of the second vane are significantly modified by the different clocking positions, in connection with the first vane modulation of the rotor secondary flows. An analysis of the performance of the second vane is also carried out, and a 0.6% variation in the second vane loss coefficient has been recorded among the different clocking positions.


Author(s):  
Mehmet Mersinligil ◽  
Jean-Franc¸ois Brouckaert ◽  
Julien Desset

This paper presents the first experimental engine and test rig results obtained from a fast response cooled total pressure probe. The first objective of the probe design was to favor continuous immersion of the probe into the engine to obtain time series of pressure with a high bandwidth and therefore statistically representative average fluctuations at the blade passing frequency. The probe is water cooled by a high pressure cooling system and uses a conventional piezo-resistive pressure sensor which yields therefore both time-averaged and time-resolved pressures. The initial design target was to gain the capability of performing measurements at the temperature conditions typically found at high pressure turbine exit (1100–1400K) with a bandwidth of at least 40kHz and in the long term at combustor exit (2000K or higher). The probe was first traversed at the turbine exit of a Rolls-Royce Viper turbojet engine, at exhaust temperatures around 750 °C and absolute pressure of 2.1bars. The probe was able to resolve the high blade passing frequency (≈23kHz) and several harmonics up to 100kHz. Besides the average total pressure distributions from the radial traverses, phase-locked averages and random unsteadiness are presented. The probe was also used in a virtual three-hole mode yielding unsteady yaw angle, static pressure and Mach number. The same probe was used for measurements in a Rolls-Royce intermediate pressure burner rig. Traverses were performed inside the flame tube of a kerosene burner at temperatures above 1600 °C. The probe successfully measured the total pressure distribution in the flame tube and typical frequencies of combustion instabilities were identified during rumble conditions. The cooling performance of the probe is compared to estimations at the design stage and found to be in good agreement. The frequency response of the probe is compared to cold shock tube results and a significant increase in the natural frequency of the line-cavity system formed by the conduction cooled screen in front of the miniature pressure sensor were observed.


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