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Showing papers by "Terrence W. Simon published in 2018"


Journal ArticleDOI
TL;DR: In this article, the effect of porous media in a high pressure liquid piston air compressor/expander, which is the proposed pressure for the ICAES system, was studied experimentally and the results indicated that the added surface area provides the dominant benefits but the porous media also increase the heat transfer coefficient at the same efficiency regime.

48 citations


Journal ArticleDOI
TL;DR: In this article, the effects of primary hole shape and injection angle on film cooling with primary and secondary hole injection were investigated. But the authors focused on the effect of the secondary hole shape.
Abstract: Film cooling with primary and secondary hole injection is numerically investigated. Effects of primary hole shape and secondary hole injection angle are documented. Each primary hole, either cylind...

20 citations


Journal ArticleDOI
TL;DR: In this paper, an active heat sink system that combines active and passive cooling components along with a suction fan is experimentally investigated, and the experimental results indicate that the micro pin fins are most efficient among the employed active and active cooling components, reducing thermal resistance up to 38%, compared to plain heat sink performance.

15 citations


Proceedings ArticleDOI
30 Aug 2018
TL;DR: In this paper, the authors present experimental and computational results for cascade representing the first stage nozzle guide vane of a high-pressure gas turbine, where the cascade is subsonic, linear, and stationary with an axisymmetrically-contoured endwall.
Abstract: Endwalls impose a challenge to cool because of the complex system of secondary flows and separation lines disrupting surface film coolant coverage. The interaction of film cooling flows with secondary flow structures is coupled. The momentum exchange of the film coolant with the mainstream affect the formation the secondary flows, which in turn affect the coolant coverage. Therefore, to develop better endwall cooling schemes, a good understanding of passage aerodynamics as affected by interactions with coolant flows is required. This study presents experimental and computational results for cascade representing the first stage nozzle guide vane of a high-pressure gas turbine. The cascade is subsonic, linear, and stationary with an axisymmetrically-contoured endwall. Two cooling flows are simulated; upstream combustor liner coolant-in the form of an aero-thermal profile simulated in the approach flow and endwall slot film cooling, which is injected immediately upstream of the passage inlet. The experiment is run with engine representative combustor exit flow turbulence intensity and integral length scales, with high turbine passage exit Reynolds number of 1.61 × 106. Measurements are performed with various slot film cooling mass flow rate to mainstream flow rate ratios (MFR). Aerodynamic effects are documented with five-hole probe measurements at the exit plane. Varying the slot film cooling MFR results in minimal effects on total pressure loss for the range tested. Vorticity distributions show a very thin, yet intense, cross-pitch flow on the contoured endwall side. Coolant distribution fields that were previously presented for the same cascade are discussed in context of the aerodynamic measurements. A coolant vorticity parameter presenting the advective mixing of the coolant due to secondary flow vorticity is introduced. This parameter gives developers a new prospective on aerodynamic-thermal performance associated with cooled turbine endwall. The numerical study is conducted for the same test section geometry and is run under the same conditions. The applicability of using RANS turbulence closure models for simulating this type of flow is discussed. The effects of including the combustor coolant in the approach flow is also briefly discussed in context of the numerical results.

4 citations


Proceedings ArticleDOI
30 Aug 2018
TL;DR: In this article, four cases of novel film cooling hole design, all based on cylindrical holes, are numerically studied, and it is shown from the simulation that the two-stage cylinder-shaped hole cannot improve film cooling effectiveness.
Abstract: In modern gas turbines, film cooling technology is the most common and efficient way to provide thermal protection for hot parts. To improve film cooling effectiveness, different kinds of shaped holes have been designed, but most of them are complicated and difficult to machine. In this study, four cases of novel film cooling hole design, all based on cylindrical holes, are numerically studied. One is a single, two-stage cylindrical hole, whose downstreamhalf-length has a diameter D while the upstreamhalf-length has a diameter D/2. A second has a cylindrical primary hole with two smaller secondary holes located symmetrically about the centerline of the primary hole and downstream of the primary hole. The three holes of this second design are then combined to make a single shaped hole, constituting a third case, called the tri-circular shaped hole. The entry part of the third case is replaced by a cylindrical hole with a diameter of half the primary hole diameter, making a fourth case called the two-stage tri-circular shaped hole. Film cooling effectiveness and surrounding thermal and flow fields are numerically investigated for all four cases using various blowing ratios. It is shown from the simulation that the two-stage cylindrical hole cannot improve film cooling effectiveness. The primary hole with two secondary holes can enhance film cooling performance by creating anti-kidney vortex pairs, which will weaken jet lift-off, caused by the kidney vortex pairs, from the primary hole. The tri-circular shaped hole will provide better film cooling effectiveness near the hole area, and is not sensitive to blowing ratio. The two-stage structure for tri-circular shaped hole provides better film coverage because it changes the flow structure inside the channel and decreases jet penetration.Copyright © 2018 by ASME

4 citations


Journal ArticleDOI
13 Apr 2018
TL;DR: In this paper, the effects of relative humidity (RH) and dry air flow on the lead iodide (PbI2) solution deposition process were investigated. And the authors concluded that the quality of the PbII2film is critical to the development of the perovskite film and the performance of PSCdevice.
Abstract: Perovskite solar cells (PSC) have outstanding potential to be low-cost, high-efficiency photovoltaic devices. The PSC can be fabricated by numerous techniques; however, the power conversion efficiency (PCE) for the two-step-processed PSC falls behind that of the one-stepmethod. In this work, we investigate the effects of relative humidity (RH) and dry air flowon the lead iodide (PbI2) solution deposition process.We conclude that the quality of the PbI2film is critical to the development of the perovskite film and the performance of the PSCdevice. LowRHand dry airflowused during the PbI2 spin coating procedure can increase supersaturation concentration to formdenser PbI2 nuclei and a more suitable PbI2 film.Moreover, airflow-assisted PbI2 drying and thermal annealing steps can smooth transformation from the nucleation stage to the crystallization stage.

3 citations




Journal ArticleDOI
TL;DR: In this paper, the authors numerically examined the endwall film cooling using curtain cooling and cooling from upstream combustor walls for the first-stage turbine vane endwall of a turbine.
Abstract: Endwall film cooling using curtain cooling and coolant discharge from upstream combustor walls is numerically examined in this study. Curtain cooling for the first-stage turbine vane endwall is acc...