Water Droplet Size Measurements in an Experimental Steam Turbine Using an Optical Fiber Droplet Sizer

Tatsuno, Kyoichi; Nagao, S.

doi:10.1115/1.3247038

Cited by 23 publications

(13 citation statements)

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“…ビン効率は 1%低下する」という経験則が発表されている (3) ．Miller らは実機サイズの試験用タービンを用いて湿り度とタービン効率の関係を求めている (4) ．Gyarmathy はタービン湿り蒸気に関する理論的解析を行い (5) ，Young は湿り蒸気流れの諸特性に関する数多くの研究成果を発表している (6)～ (9) ．最近では，非平衡凝縮モデルを CFD に組み込み，湿り段落の三次元流体解析が数多く行われている (10) (6) ，Guo らは蒸気タービンの湿り損失計算法にこの手法を適用している (14) ．しかしながら，この手法では水滴径を含む非常に多くの状態値や無次元数を入力する必要があるとともに，水滴径の予測値によって損失が大きく変化する特性を示す．従って，この手法を設計計算に適用するためには，計算精度および計算時間の改善が必要と考えられる． Fig. 3 Non-equilibrium and equilibrium expansion (18) ，広範囲の蒸気条件でスケールモデルの特性を計測できる試験用蒸気タービン (1) ，実機と同一のサイズで特性を計測できる実機蒸気タービン (19) などの試験装置によって得られる翼列の湿り損失特性 (18) ，ボアスコープによるタービン内部流れの可視化 (20) ，液滴計による水滴径の計測 (21) ，PIV プローブによる水滴速度の計測 (22) などである．また，解析結果は，蒸気タービン内の水滴の発生・成長・挙動を計算する解析手法 (13) や，種々の論文 (7),(8),(23), (24)…”

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Development of Moisture Loss Models in Steam Turbines

Kawagishi

Onoda²,

Shibukawa

et al. 2011

Trans.JSME, Ser.B

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This paper describes physics-based moisture loss models for designing wet-steam turbines. Steam turbines in wet-steam conditions experience thermodynamic and mechanical losses caused by the presence of moisture. The developed moisture loss models are composed of six categories : supersaturation loss, condensation loss, accelerating loss, braking loss, capturing loss and pumping loss. These losses are calculated according to the wetness levels in the nozzle & bucket rows, and defined by the functions of steam properties and design factors of turbine stages. The supersaturation loss produced by the non-equilibrium expansion of the wet steam is modeled using the pressure ratio and the isentropic exponent in the supersaturated steam. The loss models are applied to the full-size test turbine data for the prediction of the overall moisture losses. As a result, the developed loss models are found to be very effective for estimating the moisture losses of turbine stages.

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Development of Moisture Loss Models in Steam Turbines

Kawagishi

Onoda²,

Shibukawa

et al. 2011

Trans.JSME, Ser.B

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“…The calculated value is in agreement with a previous report on the droplet size distribution of the water vapor system. 32,33,34,35 As the vapor droplets act as sub-micro reactors, the primary particles are limited not only to growth but also condense together to form the final morphology, as shown in the FE-SEM image.…”

Section: Resultsmentioning

confidence: 99%

Sub-micro droplet reactors: Green synthesis of Li3VO4 anode materials for lithium ion batteries

Ha¹,

Vu²,

Ha³

et al. 2020

Preprint

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A new green-chemistry strategy, based on modified solid-state reaction with the addition of water vapor to accelerate acid-base reactions (ABR) at low temperature, was developed along with Ca-doping to synthesize electrode material for lithium-ion batteries. The new method which helps in control the particles size and saving energy in synthesis has been developed. To explain this process, we proposed a mechanism in which water droplets play a key role as sub-micro reactors, calculated as few tens of nanometers, to ensure proper reaction conditions and confine crystal growth to nano-dimensions. The synergic effect of the proposed ABR method and Ca-doping is discussed to further explain the increase in the specific surface area and electrochemical performance of the anode material. The optimized material, Ca-doped Li3VO4, delivers a superior specific capacity of 543.1 mAh⸳g-1 after 200 cycles at a current density of 100 mA⸳g-1, which could be attributed to the contribution of pseudocapacitance.

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“…where, h lv and R v are latent heat of phase change and specific gas constant. The liquid surface tension σ is expressed as 2 13 1…”

Section: Nucleation and Droplet Growthmentioning

confidence: 99%

“…Tatsuno and Nagao [13] used the forward scattering method to measure the average droplet size at the outlet of last stage blade. Ahmad et al [14] found through experiments that the erosion of turbine blade will grow as increasing sizes of droplet.…”

Section: Introductionmentioning

confidence: 99%