Effect of the inlet gas void fraction on the tip leakage vortex in a multiphase pump

The inlet gas void fraction (IGVF) has a great effect on the power performance of the multiphase pump, and the effect is even greater under the cavitation condition. To reveal the effect of the IGVF on the cavitation evolution and the work performance of the multiphase pump at different cavitation stages, the cavitation flow was calculated numerically for the pump under different inlet gas void fractions (IGVFs) of 0%, 10% and 20%. Meanwhile, the numerical simulation method was verified experimentally. The results showed that the increase of the IGVF could improve the cavitation performance of the multiphase pump and inhibit the increasing rate of the vapor. With the aggravation of the cavitation, the output power of the impeller decreased gradually under different IGVFs. In addition, the variation trend of the output power and the net energy gained by the fluid within each domain were exactly the same. At the same time, the position of better work performance was located in the impeller fore area at the critical and serious cavitation stages, while when the cavitation developed to the fracture cavitation, the position of better work performance moved to the impeller back area. At the fracture cavitation stage, the main work region of the multiphase pump moved from the back area to the fore area of the impeller with the increase of the IGVF. The research results are of great significance in improving the performance of the multiphase pump.

Download Full-text

Gas Void Fraction Prediction for Air-Water and Air-Oil Two-Phase Flows via Artificial Neural Network

10.26678/abcm.jem2019.jem19-0017 ◽

2019 ◽

Author(s):

Tiago Ferreira Souza ◽

Caio Araujo ◽

Maurício Figueiredo ◽

FLAVIO SILVA ◽

Ana Maria Frattini Fileti

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Void Fraction ◽

Two Phase Flows ◽

Two Phase ◽

Artificial Neural ◽

Gas Void Fraction

Download Full-text

Flow Field Unsteadiness in the Tip Region of a Transonic Compressor Rotor

Journal of Fluids Engineering ◽

10.1115/1.2819097 ◽

1997 ◽

Vol 119 (1) ◽

pp. 122-128 ◽

Cited By ~ 2

Author(s):

S. L. Puterbaugh ◽

W. W. Copenhaver

Keyword(s):

Flow Field ◽

High Performance ◽

Three Dimensional ◽

Navier Stokes ◽

Vortex Interaction ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Transonic Compressor ◽

Compressor Rotor ◽

Operating Points

An experimental investigation concerning tip flow field unsteadiness was performed for a high-performance, state-of-the-art transonic compressor rotor. Casing-mounted high frequency response pressure transducers were used to indicate both the ensemble averaged and time varying flow structure present in the tip region of the rotor at four different operating points at design speed. The ensemble averaged information revealed the shock structure as it evolved from a dual shock system at open throttle to an attached shock at peak efficiency to a detached orientation at near stall. Steady three-dimensional Navier Stokes analysis reveals the dominant flow structures in the tip region in support of the ensemble averaged measurements. A tip leakage vortex is evident at all operating points as regions of low static pressure and appears in the same location as the vortex found in the numerical solution. An unsteadiness parameter was calculated to quantify the unsteadiness in the tip cascade plane. In general, regions of peak unsteadiness appear near shocks and in the area interpreted as the shock-tip leakage vortex interaction. Local peaks of unsteadiness appear in mid-passage downstream of the shock-vortex interaction. Flow field features not evident in the ensemble averaged data are examined via a Navier-Stokes solution obtained at the near stall operating point.

Download Full-text

Unsteady Aperiodic Behavior of a Periodically Disturbed Tip-Leakage Vortex

AIAA Journal ◽

10.2514/1.13539 ◽

2008 ◽

Vol 46 (5) ◽

pp. 1025-1038 ◽

Cited By ~ 1

Author(s):

Ruolong Ma ◽

William J. Devenport

Keyword(s):

Tip Leakage Vortex ◽

Tip Leakage

Download Full-text

Measurements of the Tip Clearance Flow for a High-Reynolds-Number Axial-Flow Rotor

Journal of Turbomachinery ◽

10.1115/1.2836564 ◽

1995 ◽

Vol 117 (4) ◽

pp. 522-532 ◽

Cited By ~ 23

Author(s):

W. C. Zierke ◽

K. J. Farrell ◽

W. A. Straka

Keyword(s):

Reynolds Number ◽

Flow Visualization ◽

Vortex Core ◽

Rotor Blade ◽

High Reynolds Number ◽

Tip Clearance ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Blade Tip ◽

High Reynolds

A high-Reynolds-number pump (HIREP) facility has been used to acquire flow measurements in the rotor blade tip clearance region, with blade chord Reynolds numbers of 3,900,000 and 5,500,000. The initial experiment involved rotor blades with varying tip clearances, while a second experiment involved a more detailed investigation of a rotor blade row with a single tip clearance. The flow visualization on the blade surface and within the flow field indicate the existence of a trailing-edge separation vortex, a vortex that migrates radially upward along the trailing edge and then turns in the circumferential direction near the casing, moving in the opposite direction of blade rotation. Flow visualization also helps in establishing the trajectory of the tip leakage vortex core and shows the unsteadiness of the vortex. Detailed measurements show the effects of tip clearance size and downstream distance on the structure of the rotor tip leakage vortex. The character of the velocity profile along the vortex core changes from a jetlike profile to a wakelike profile as the tip clearance becomes smaller. Also, for small clearances, the presence and proximity of the casing endwall affects the roll-up, shape, dissipation, and unsteadiness of the tip leakage vortex. Measurements also show how much circulation is retained by the blade tip and how much is shed into the vortex, a vortex associated with high losses.

Download Full-text

The Behavior of the Casing Boundary Layer With the Presence of Tip Leakage Vortex

Volume 2A: Turbomachinery ◽

10.1115/gt2018-75916 ◽

2018 ◽

Cited By ~ 2

Author(s):

Xi Nan ◽

Feng Lin ◽

Takehiro Himeno ◽

Toshinori Watanabe

Keyword(s):

Boundary Layer ◽

Skin Friction ◽

Three Dimensional ◽

Pressure Rise ◽

Rotating Stall ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Transonic Compressor ◽

Flow Loss ◽

Produce Flow

Casing boundary layer effectively places a limit on the pressure rise capability achievable by the compressor. The separation of the casing boundary layer not only produce flow loss but also closely related to the compressor rotating stall. The motivation of this paper is to present a viewpoint that the casing boundary layer should be paid attention to in parallel with other flow factors on rotating stall trigger. This paper illustrates the casing boundary layer behavior by displaying its separation phenomena with the presence of tip leakage vortex at different flow conditions. Skin friction lines and the corresponding absolute streamlines are used to demonstrate the three-dimensional flow patterns on and near the casing. The results depict a Saddle, a Node and several tufts of skin friction lines dividing the passage into four zones. The tip leakage vortex is enfolded within one of the zones by the separated flows. All the flows in each blade passage are confined within the passage as long as the compressor is stable. The casing boundary layer of a transonic compressor is also examined in the same way, which results in qualitatively similar zonal flows that enfolds the tip leakage vortex. This research develops a new way to study the casing boundary layer in rotating compressors. The results may provide a first-principle based explanation to stalling mechanisms for compressors that are casing sensitive.

Download Full-text

Unsteady Tip Leakage Vortex Cavitation Originating From the Tip Clearance of an Oscillating Hydrofoil

Journal of Fluids Engineering ◽

10.1115/1.2173290 ◽

2005 ◽

Vol 128 (3) ◽

pp. 421-429 ◽

Cited By ~ 22

Author(s):

Masahiro Murayama ◽

Yoshiki Yoshida ◽

Yoshinobu Tsujimoto

Keyword(s):

Steady State ◽

Qualitative Agreement ◽

Cavity Growth ◽

Simple Calculation ◽

Tip Clearance ◽

Cavity Volume ◽

Cavity Size ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Unsteady Characteristics

Tip leakage vortex cavitations originating from the tip clearance of an oscillating hydrofoil were observed experimentally. It was found that the delay between the unsteady and the steady-state results of the tip leakage vortex cavitation increase, and that the maximum cavity size decreases when the reduced oscillating frequency increases. To simulate the unsteady characteristics of tip leakage vortex cavitation, a simple calculation based on slender body approximation was conducted taking into account the effect of cavity growth. The calculation and experimental results of the cavity volume fluctuation were found to be in qualitative agreement.

Download Full-text