Unsteady Pressure Measurements With a Fast Response Cooled Probe in High Temperature Gas Turbine Environments

Abstract

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 a 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 piezoresistive 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 (800–1100°C) with a bandwidth of at least 40 kHz and in the long term at combustor exit (2000 K 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 2.1 bars. The probe was able to resolve the high blade passing frequency (≈23 kHz) and several harmonics of up to 100 kHz. Besides the average total pressure distributions rom 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 with estimations at the design stage and found to be in good agreement. The frequency response of the probe is compared with 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.

Fiber-optic integrated aerodynamic three-hole vector probe for high-velocity flow field measurement

“…From some literature reports as well as our previous measurement experience and demands in general flow fields, the angular measurement ranges of À15 -15 of THP can already be applied to some typical turbomachinery studies, such as turbine rotor blades, horseshoe vortices, and turbine cascades, etc (Soto-Valle et al, 2020;Mersinligil et al, 2011;Beer, 2008;Teng, 2021). Therefore, within this angular range of À15 -15 , the feasibility of the fiber-optic integrated aerodynamic THP and multi-channel WLI interrogator for iScience Article flow field calibration and velocity vector measurements was verified.…”

Technology Development of Fast-Response Aerodynamic Pressure Probes

“…The probe design concept allows to deal with a relatively high temperature. Present-day piezoelectric transducers can operate up to about 550 K and epoxy resins are commercially available for temperatures greater than 600 K. The combination of these two elements allows manufacturing high-temperature FRAPP in a straightforward way and without external cooling-a topic that, however, has been the object of dedicated investigations [27] that proved to be successful at the cost of an increase of probe blockage.…”

Characterization of Periodic Incoming Wakes in a Low-Pressure Turbine Cascade Test Section by Means of a Fast-Response Single Sensor Virtual Three-Hole Probe

“…/d ≈ 25) would lead to significant errors in the measurement of the time mean total pressure downstream of the bars if one was to use a conventional pneumatic (directional) probe [2]. For this reason, a directional probe with a single fast-response pressure sensor has been used in a virtual three-hole mode, as described by Mersinligil et al [8] and by Dell'Era et al [9,10].…”