Mist/Steam Heat Transfer in Confined Slot Jet Impingement

Abstract

Internal mist/steam blade cooling technology has been considered for the future generation of Advanced Turbine Systems (ATS). Fine water droplets of about 5 μm were carried by steam through a single slot jet onto a heated target surface in a confined channel. Experiments covered Reynolds numbers from 7500 to 25,000 and heat fluxes from 3 to 21 kW/m2. The experimental results indicate that the cooling is enhanced significantly near the stagnation point by the mist, decreasing to a negligible level at a distance of six jet widths from the stagnation region. Up to 200 percent heat transfer enhancement at the stagnation point was achieved by injecting only ∼1.5 percent of mist. The investigation has focused on the effects of wall temperature, mist concentration, and Reynolds number.

Second-moment closure simulation of flow and heat transfer in a gas-droplets turbulent impinging jet

“…Comparison between predictions and data for steam-droplet impinging slot jet of [15] is shown in Fig. 13.…”

“…Papers [15,16,18] deal with experimental [15] and numerical [16,18] investigations of steam-droplets slot jet impingement heat transfer on the flat and concave surfaces. The impinging two-phase jet is numerically simulated with the use of the CFD-package "FLUENT" with application of EulerianeLagrangian method.…”

Mist/steam heat transfer of multiple rows of impinging jets

“…Published data also show that the addition of mist to an air or steam flow can enhance heat transfer significantly [1][2][3][4][5][6]. It has been recognized that mist/steam jet impingement could be an excellent candidate for enhancing gas turbine heat transfer.…”

“…Fig. 2a shows the schematic of the test section, which has the identical structure as in [4] except the injection plate. Fig.…”

“…The overall cooling enhancement of the mist/ steam flow ranged from 40% to 300% with maximum local cooling enhancement being over 800%, which occurred at about 45°downstream of the inlet of the test section. Li et al [4] reported results of mist/steam cooling with a slot jet on a heated flat surface. It was found that stagnation point heat transfer could be enhanced over 200% by adding 1.5% mist (in mass) to the steam flow.…”