PIV measurements in a twin-jet STOVL fountain flow

Abstract

Mean velocity and first order turbulence measurements were obtained from a three-dimensional upwash fountain flow generated by the impingement of two compressible axisymmetric turbulent jets onto a normal plane. The jet impingement area and fountain formation regions were examined with data obtained through the use of particle image velocimetry. Seven configurations with different nozzle pressure ratios were considered to ascertain the influence of jet compressibility on the fountain development. Results indicate that the mixing of the fountain is dependent on the nozzle pressure ratio, leading to an increase in the fountain spreading rate with increase in nozzle pressure ratio.

Turbulence Measurements in a Short Take-Off Vertical-Landing Fountain

“…Techniques such as particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) offer the possibility of detailed non-intrusive measurements in the fountain region. Recently we have reported on the mean impinging jet and fountain velocity profiles obtained using PIV and LDV [5][6][7]. This paper extends the work further by presenting PIV-derived fountain turbulence characteristics.…”

An experimental investigation on the interaction of hydraulic jumps formed by two normal impinging circular liquid jets

“…Most studies on twin impinging jets have been on air (or a compressible fluid) jets. Following the studies of Siclari, Migdal & Luzzi (1976), Siclari et al (1977), Siclari, Hill & Jenkins (1981), Hill & Jenkins (1980), Saripalli (1983), Hill (1985), Gilbert (1989), Miller (1995), Barata (1996), and Cabrita, Saddington & Knowles (2005), it can be inferred that the flow due to twin impinging jets, in general, is characterized by the following distinct regions (see figure 2):…”

“…The fountain flow is known to involve complex flow structures; it has growth rates considerably larger than the growth rates found in free plane jets, and turbulent mixing rates are considerably higher in upwash flows than in other free turbulent flows (Hill 1985). The fountain is quite sensitive to small imbalances between the jets and appears to be unstable under certain conditions (Cabrita et al 2005;Skifstad 1970).…”

Effects of Nozzle Pressure Ratio and Nozzle-to-Plate Distance to Flowfield Characteristics of an Under-Expanded Jet Impinging on a Flat Surface

“…In addition, color contours of turbulent kinetic energy clearly depict the peak values in the region of the stand-off shocks rather than in the shear layers as previously shown for the low-pressure ratio measurements. Such observation suggests that the turbulence fields can be also used as the indicator for the location of the stand-off shock (Cabrita et al [4]). Krothapalli et al [3] performed experimental studies of flow field and noise characteristics of an axisymmetric supersonic jet issuing from a sonic and a Mach 1.5 converging-diverging nozzle and impinging on a ground plane.…”

“…The impinging jet configuration has received many considerations from researchers due to its widespread use in many industrial applications. For example, the impinging jets can be used for cooling of hot surfaces such as turbine blade (Saddington et al [1], Hadžiabdić and Hanjalić [2]), as rocket engine or vertical and short take off and landing aircraft (Krothapalli et al [3], Cabrita et al [4], Saddington et al [5,6], Wilke and Sesterhenn [7]), and as torque generator in turbomachinery system.…”