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10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on MgP(CO4)2 by Materials Project

MgP(CO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of two MgP(CO4)2 ribbons oriented in the (0, 0, 1) direction. Mg is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Mg–O bond distances ranging from 1.95–2.62 Å. There are two inequivalent C sites. In the first C site, C is bonded in a distorted linear geometry to one P and one O atom. The C–P bond length is 2.00 Å. The C–O bond length is 1.14 Å. In the second C site, C is bonded in a linear geometry to two O atoms. There is one shorter (1.17 Å) and one longer (1.18 Å) C–O bond length. P is bonded in a distorted trigonal planar geometry to one C and three O atoms. There are a spread of P–O bond distances ranging from 1.47–1.52 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Mg and one C atom. In the second O site, O is bonded in a single-bond geometry to one C atom. In the third O site, O is bonded in a single-bond geometry to one Mg atom. In the fourth O site, O is bonded in a single-bond geometry to one Mg atom. In the fifth O site, O is bonded in a single-bond geometry to one P atom. In the sixth O site, O is bonded in a bent 150 degrees geometry to one Mg and one P atom. In the seventh O site, O is bonded in a bent 150 degrees geometry to one Mg and one P atom. In the eighth O site, O is bonded in a single-bond geometry to one C atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgP(HO)7 by Materials Project

MgP(HO)7 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.17 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent MgO6 octahedra. The corner-sharing octahedra tilt angles range from 13–44°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.56 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one P5+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one P5+, and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a linear geometry to one Mg2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(MgP)2 by Materials Project

Ba(MgP)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ba2+ is bonded to six equivalent P3- atoms to form BaP6 octahedra that share corners with twelve equivalent MgP4 tetrahedra, edges with six equivalent BaP6 octahedra, and edges with six equivalent MgP4 tetrahedra. All Ba–P bond lengths are 3.30 Å. Mg2+ is bonded to four equivalent P3- atoms to form MgP4 tetrahedra that share corners with six equivalent BaP6 octahedra, corners with six equivalent MgP4 tetrahedra, edges with three equivalent BaP6 octahedra, and edges with three equivalent MgP4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–50°. There are one shorter (2.64 Å) and three longer (2.65 Å) Mg–P bond lengths. P3- is bonded in a 7-coordinate geometry to three equivalent Ba2+ and four equivalent Mg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgP by Materials Project

MgP crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six P2- atoms. There are a spread of Mg–P bond distances ranging from 2.60–2.86 Å. In the second Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six P2- atoms. There are a spread of Mg–P bond distances ranging from 2.58–2.87 Å. There are two inequivalent P2- sites. In the first P2- site, P2- is bonded in a 7-coordinate geometry to six Mg2+ and one P2- atom. The P–P bond length is 2.21 Å. In the second P2- site, P2- is bonded to six Mg2+ atoms to form distorted corner-sharing PMg6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgP(CO3)2 by Materials Project

MgP(CO3)2 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Mg2+ is bonded in a 5-coordinate geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.00–2.68 Å. There are two inequivalent C+2.50+ sites. In the first C+2.50+ site, C+2.50+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.19 Å. In the second C+2.50+ site, C+2.50+ is bonded in a bent 150 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.23 Å. P5+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of P–O bond distances ranging from 1.50–1.55 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Mg2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mg2+ and one C+2.50+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Mg2+ and one C+2.50+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C+2.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(MgP)2 by Materials Project

Eu(MgP)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent P3- atoms to form MgP4 tetrahedra that share corners with six equivalent EuP6 octahedra, corners with six equivalent MgP4 tetrahedra, edges with three equivalent EuP6 octahedra, and edges with three equivalent MgP4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–53°. There are three shorter (2.62 Å) and one longer (2.69 Å) Mg–P bond lengths. Eu2+ is bonded to six equivalent P3- atoms to form EuP6 octahedra that share corners with twelve equivalent MgP4 tetrahedra, edges with six equivalent EuP6 octahedra, and edges with six equivalent MgP4 tetrahedra. All Eu–P bond lengths are 3.12 Å. P3- is bonded in a 7-coordinate geometry to four equivalent Mg2+ and three equivalent Eu2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgPH16NO10 by Materials Project

MgNH4PO4(H2O)6 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional and consists of two ammonium molecules and one MgP(H6O5)2 framework. In the MgP(H6O5)2 framework, Mg2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.07–2.15 Å. P5+ is bonded in a tetrahedral geometry to four O2- atoms. All P–O bond lengths are 1.56 Å. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.69 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.61 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.60 Å) H–O bond length. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.69 Å) H–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one P5+ and two equivalent H1+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one P5+ and three H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two equivalent H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Fault Characterization and Diagnostics Supporting Condition-Based Operation and Maintenance of Gas Turbine Engines

Condition-Based Operation and Maintenance (CBOM) is the state-of-the-art in maintenance approaches for gas turbine engines. CBOM applies engine sensor information to the optimization of future operation and maintenance procedures; this technique reduces costs for engine operators by minimizing unplanned outages and catastrophic engine degradation. However, due to the complexities of gas turbine operation and the lack of available engine sensors, further development is required to fully realize the benefits of CBOM. In the turbine section, rotating components interact with high temperature flows, which creates intense thermal and mechanical stresses. As a result, there are numerous mechanisms of component degradation in the turbine section. Furthermore, turbine components – like stator vanes and rotor blades – are among the most expensive in the engine because they are complex to design and manufacture. For these reasons, this dissertation addresses two main questions: (i) which parameters or faults within the turbine section are most important to monitor, and (ii) how can these parameters or faults be monitored in an engine-relevant environment? Although many turbine parameters and faults have been investigated in the open literature, there are some faults that are still not well understood. Rotor-casing eccentricity, which causes a non-constant blade tip clearance around the annulus, has not been investigated in terms of its effects on turbine efficiency. Therefore, the first study in this dissertation quantifies overall and local turbine efficiency for varying levels of rotor-casing eccentricity. Results showed negligible variations to overall turbine efficiency, meaning rotor-casing eccentricity only becomes relevant to CBOM when its severity causes rotordynamic issues. Purge flow is critical to turbine hardware longevity because it prevents ingestion of hot main gas path (MGP) flow into the under-platform regions. Despite its importance, there are currently no methods for monitoring purge flow performance in an engine environment. Therefore, the second study in this dissertation develops a predictive model for sealing effectiveness using inputs from two fast-response pressure sensors. Results exhibited low prediction errors across a full range of purge flow rates, which supports the viability of the modelling approach for CBOM. The final two studies in this dissertation address blade coolant flow monitoring. This cooling flow is responsible for protecting the turbine blades from the MGP flow, which exits the combustor at temperatures greater than the blade melting point. These studies showed that temperature measurements on the blade surface can be used to accurately predict blade coolant flow rate, and that defining the candidate features relative to the coolant trajectory is important for maintaining accuracy as coolant flow rate degradation occurs. This work enables blade coolant flow monitoring, which is currently not possible through existing condition monitoring techniques.

condition-based, gas turbines, diagnostics,↗
DOE OSTI2020

Evaluating the Effect of Vane Trailing Edge Flow on Turbine Rim Sealing

Abstract Modern gas turbine development continues to move toward increased overall efficiency, driven in part by higher firing temperatures that point to a need for more cooling air to prevent catastrophic component failure. However, using additional cooling flow bled from the upstream compressor causes a corresponding detriment to overall efficiency. A primary candidate for cooling flow optimization is purge flow, which contributes to sealing the stator–rotor cavity and prevents ingestion of hot main gas path (MGP) flow into the wheelspace. Previous research has identified that the external main gas path flow physics play a significant role in driving rim seal ingestion. However, the potential impact of other cooling flow features on ingestion behavior, such as vane trailing edge (VTE) flow, is absent in the open literature. This paper presents experimental measurements of rim cavity cooling effectiveness collected from a one-stage turbine operating at engine-representative Reynolds and Mach numbers. Carbon dioxide (CO2) was used as a tracer gas in both the purge flow and vane trailing edge flow to investigate flow migration into and out of the wheelspace. Results show that the vane trailing edge flow does in fact migrate into the rim seal and that there is a superposition relationship between individual cooling flow contributions. Computational fluid dynamics (CFD) simulations using unsteady Reynolds-averaged Navier–Stokes (URANS) were used to confirm VTE flow ingestion into the rim seal cavity. Radial and circumferential traverse surveys were performed to quantify cooling flow radial migration through the main gas path with and without vane trailing edge flow. The surveys confirmed that vane trailing edge flow is entrained into the wheelspace as purge flow is reduced. Local CO2 measurements also confirmed the presence of VTE flow deep in the wheelspace cavity.

Engineering↗