Experimental Investigations on Three-Dimensional Blading Optimization for Low-Speed Model Testing

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Chenkai Zhang ◽  
Jun Hu ◽  
Zhiqiang Wang ◽  
Jun Li
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Optimization Procedure ◽  
Model Testing ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Flow Mechanism ◽  
Forward Movement ◽  
Low Speed

Low-speed model testing (LSMT) plays a key role in advanced multistage high-pressure compressor (HPC) design recently, due to this, employing low-speed large-scale compressor to conduct 3D blading design and detailed flow mechanism investigation is convenient and cost-saving. This paper is one portion of a whole LSMT project for the seventh stage of an advanced commercial HPC, and experimental investigations of 3D blading optimizations for LSMT were presented in this paper, consisting of overall performances for the compressor and stage 3 and detailed flowfield measurements including area traverse for rotor 3 inlet, stator 3 inlet and outlet, area traverse inside stator 3 passage, and static pressure on stator 3 blade surface. Compared with the datum compressor, revised rotor 3 is J-type and hub restaggered, and the improved stator 3 possesses characteristics of controlled camber angle, reduced leading blade angle, forward movement of maximum thickness position, and larger bowed-shape. Experimental results show that efficiency is improved by 1%, and total pressure rise for the compressor and the third stage is raised by 1.4% and 10%, respectively, while the stalling mass flow rate is maintained. The effectiveness of improved design methods is confirmed, and it is a guide for further blading design and optimization, furthermore, detailed flowfield measurements reveal the basic flow mechanism of all the improvement methods. Moreover, the results indicate that utilization of cfd code in the optimization procedure is promising, and the reliability and feasibility of cfd code are verified with the detailed experimental results.

Low-Speed Model Testing Studies for an Exit Stage of High Pressure Compressor

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Chenkai Zhang ◽  
Zhiqiang Wang ◽  
Chao Yin ◽  
Wei Yan ◽  
Jun Hu
Keyword(s):  
High Performance ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Experimental Studies ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Model Testing ◽  
Low Speed ◽  
Compressor Design ◽  
Model Compressor

This paper discusses detailed experimental studies of a low-speed large-scale axial compressor, which is typical of an exit stage of HPC. Numerous measuring techniques were performed, and detailed experimental results were obtained, including inlet boundary layer total pressure distributions, overall compressor and model-stage performance, traverse flow field between blade rows and inside the stator for the model stage, static pressure on the stator blade and casing dynamic pressure of the rotor. The objective of the study is to assess the low-speed model compressor design and verify 3D computational fluid dynamics (CFD) code. Results show that inlet endwall blockage requirement of HPC exit stage is achieved; the low-speed model compressor design is fundamentally successful; the flow rate and pressure rise requirements are met at the design operating point, although the flow loss is relatively larger than design values for the lower half span, which can be attributed to a certain hub-corner separation. Furthermore, the reliability of adopted 3D commercial CFD code is validated. It is proved that the low-speed model testing technique is still a prospective way for the design of high performance HPC.

scholarly journals RV instantaneous intraventricular diastolic pressure and velocity distributions in normal and volume overload awake dog disease models

2003 ◽  
Vol 285 (5) ◽  
pp. H1956-H1965 ◽  
Author(s):  
Ares Pasipoularides ◽  
Ming Shu ◽  
Ashish Shah ◽  
Alessandro Tucconi ◽  
Donald D. Glower
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Diastolic Pressure ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Volume Overload ◽  
Spatiotemporal Resolution ◽  
Intraventricular Flow ◽  
Normal Wall

Intraventricular diastolic right ventricular (RV) flow field dynamics were studied by functional imaging using three-dimensional (3D) real-time echocardiography with sonomicrometry and computational fluid dynamics in seven awake dogs at control with normal wall motion (NWM) and RV volume overload with diastolic paradoxical septal motion. Burgeoning flow cross section between inflow anulus and chamber walls induces a convective pressure rise, which represents a “convective deceleration load” (CDL). High spatiotemporal resolution dynamic pressure and velocity distributions of the intraventricular RV flow field revealed time-dependent, subtle interactions between intraventricular local acceleration and convective pressure gradients. During the E-wave upstroke, the total pressure gradient along intraventricular flow is the algebraic sum of a pressure decrease contributed by local acceleration and a pressure rise contributed by a convective deceleration that partially counterbalances the local acceleration gradient. This underlies the smallness of early diastolic intraventricular gradients. At peak volumetric inflow, local acceleration vanishes and the total adverse intraventricular gradient is convective. During the E-wave downstroke, the strongly adverse gradient embodies the streamwise pressure augmentations from both local and convective decelerations. It induces flow separation and large-scale vortical motions, stronger in NWM. Their dynamic corollaries on intraventricular pressure and velocity distributions were ascertained. In the NWM pattern, the strong ring-like vortex surrounding the central core encroaches on the area available for flow toward the apex. This results in higher linear velocities later in the downstroke of the E wave than at peak inflow rate. The augmentation of CDL by ventriculoannular disproportion may contribute to E wave and E-to-A ratio depression with chamber dilatation.

Computational and experimental investigations in a cyclone dust separator

1997 ◽  
Vol 211 (4) ◽  
pp. 247-257 ◽  
Author(s):  
S M Fraser ◽  
A M Abdel-Razek ◽  
M Z Abdullah
Keyword(s):  
Flow Field ◽  
Richardson Number ◽  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Cyclone Chamber ◽  
Dust Separator

Three-dimensional turbulent flow in a model cyclone has been simulated using PHOENICS code and experimental studies carried out using a laser Doppler anemometry (LDA) system. The experimental results were used to validate the computed velocity distributions based on the standard and a modified k-∊ model. The standard k-∊ model was found to be unsatisfactory for the prediction of the flow field inside the cyclone chamber. By considering the strong swirling flow and the streamlined curvature, a k-∊ model, modified to take account of the Richardson number, provided better velocity distributions and better agreement with the experimental results.

An Experimental Study of Stall Suppression and Associated Changes to the Flow Structures in the Tip Region of an Axial Low Speed Fan Rotor by Axial Casing Grooves

2017 ◽  
Author(s):  
Huang Chen ◽  
Yuanchao Li ◽  
Subhra Shankha Koley ◽  
Nick Doeller ◽  
Joseph Katz
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Pressure Rise ◽  
Leading Edge ◽  
Suction Side ◽  
Rotating Stall ◽  
Flow Structures ◽  
Flow Angle ◽  
Low Speed ◽  
Flow Characterization

The effects of axial casing grooves on the performance and flow structures in the tip region of an axial low speed fan rotor have been studied experimentally in the JHU refractive index-matched liquid facility. The four-per-passage semicircular grooves are skewed by 45° in the positive circumferential direction, and have a diameter of 65% of the rotor blade axial chord length. A third of the groove overlaps with the blade front, and the rest extends upstream. These grooves have a dramatic effect on the machine performance, reducing the stall flow rate by 40% compared to the same machine with a smooth endwall. However, they reduce the pressure rise at high flow rates. The flow characterization consists of qualitative visualizations of vortical structures using cavitation, as well as stereo-PIV (SPIV) measurements in several meridional and (z,θ) planes covering the tip region and interior of the casing grooves. The experiments are performed at a flow rate corresponding to pre-stall conditions for the untreated machine. They show that the flow into the downstream sides of the grooves and the outflow from their upstream sides vary periodically. The inflow peaks when the downstream end is aligned with the pressure side (PS) of the blade, and decreases, but does not vanish, when this end is located near the suction side (SS). These periodic variations have three primary effects: First, substantial fractions of the leakage flow and the tip leakage vortex (TLV) are entrained periodically into the groove. Consequently, in contrast to the untreated flow, The TLV remnants remain confined to the vicinity of the entrance to the groove, and the TLV strength diminishes starting from the mid-chord. Second, the grooves prevent the formation of large scale backflow vortices (BFVs), which are associated with the TLV, propagate from one blade passage to the next, and play a key role in the onset of rotating stall in the untreated fan. Third, the flow exiting from the grooves causes periodic variations of about 10° in the relative flow angle around the blade leading edge, presumably affecting the blade loading. The distributions of turbulent kinetic energy provide statistical evidence that in contrast to the untreated casing, very little turbulence originating from a previous TLV, including the BFVs, propagates from the PS to the SS of the blade. Hence, the TLV-related turbulence remain confined to the entrance to groove. Elevated, but lower turbulence is also generated as the outflow from the groove jets into the passage.

Small-Scale Models for Testing Masonry Structures

2010 ◽  
Vol 133-134 ◽  
pp. 497-502 ◽  
Author(s):  
Alvaro Quinonez ◽  
Jennifer Zessin ◽  
Aissata Nutzel ◽  
John Ochsendorf
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Three Dimensional ◽  
Model Testing ◽  
Scale Model ◽  
Small Scale ◽  
Material Strength ◽  
Masonry Structures ◽  
Scale Models ◽  
Set Up

Experiments may be used to verify numerical and analytical results, but large-scale model testing is associated with high costs and lengthy set-up times. In contrast, small-scale model testing is inexpensive, non-invasive, and easy to replicate over several trials. This paper proposes a new method of masonry model generation using three-dimensional printing technology. Small-scale models are created as an assemblage of individual blocks representing the original structure’s geometry and stereotomy. Two model domes are tested to collapse due to outward support displacements, and experimental data from these tests is compared with analytical predictions. Results of these experiments provide a strong understanding of the mechanics of actual masonry structures and can be used to demonstrate the structural capacity of masonry structures with extensive cracking. Challenges for this work, such as imperfections in the model geometry and construction problems, are also addressed. This experimental method can provide a low-cost alternative for the collapse analysis of complex masonry structures, the safety of which depends primarily on stability rather than material strength.

The Potential of Rotor and Stator Clocking in a 2.5-Stage Low-Speed Axial Compressor

2012 ◽  
Author(s):  
J. Städing ◽  
J. Friedrichs ◽  
T. Waitz ◽  
C. Dobriloff ◽  
B. Becker ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Axial Flow ◽  
Pressure Rise ◽  
Boundary Layer Transition ◽  
Experimental Investigations ◽  
Layer Transition ◽  
Low Speed ◽  
Beneficial Effects ◽  
Pass Through ◽  
Flow Compressor

Detailed experimental investigations have been conducted to gain profound knowledge of airfoil clocking mechanisms in axial compressors. Clocking, the circumferential indexing of adjacent rotor or stator rows with equal blade counts, is known as a potential means to modify the flow field in multistage turbo-machinery and increase overall efficiencies of both turbines and compressors. These beneficial effects on turbomachine performance are due to wake-airfoil interactions and primarily depend on the alignment of a downstream blade or vane row with upstream wake trajectories that are generated in the same frame of reference. The present survey describes and discusses the experimental research on Rotor and Stator Clocking effects in a low-speed 2.5-stage axial flow compressor. For both Rotor and Stator Clocking, variations of Stage 2 performance have been found that are sinusoidal in trend over the clocking angle and originate from a significant change in static pressure rise across the clocked blade rows. Time-averaged measurements basically suggest the highest pressure gain, if the upstream wakes pass through mid-passage of the downstream blade row. In case of Rotor Clocking, this may even lead to a variation in compressor operating range. The fundamental aerodynamic mechanism responsible for the clocking effect can be attributed to a shift of the suction-sided boundary layer transition over the clocking angle. Regarding overall Stage 2 performance, the investigations show that Full Clocking, i.e. the combination of Rotor and Stator Clocking, nearly doubles the potential of single row indexing.

scholarly journals The Design and Testing of a Radial Flow Turbine for Aerodynamic Research

1991 ◽  
Author(s):  
I. Huntsman ◽  
H. P. Hodson ◽  
S. H. Hill
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Three Dimensional ◽  
Surface Flow ◽  
Stream Line ◽  
Flow Visualisation ◽  
Gas Generator ◽  
Low Speed ◽  
Scaling Parameters ◽  
Design And Testing

This paper describes the design of a high-speed radial inflow turbine for use as part of a gas-generator, and the design of a large-scale (1.2 m tip dia.) low-speed model of the high-speed turbine. Stream-line curvature throughflow, two-dimensional blade-to-blade and fully three-dimensional inviscid and viscous calculation methods have been used extensively in the analysis of the designs. The use of appropriate scaling parameters and their impact on turbine performance is discussed. A simple model shows, for example, how to model the blade lean in the inducer which serves to balance the effect of meridional curvature at inlet to the rotor and can be used to unload the rotor tip. A brief description of the low speed experimental facility is followed by a presentation and discussion of experimental results. These include surface flow visualisation patterns on both the rotor and stator blades and blade row exit traverses.

Numerical and Experimental Investigation on a Low-Speed Compressor Cascade With Circulation Control

2008 ◽  
Author(s):  
S. Fischer ◽  
H. Saathoff ◽  
R. Radespiel
Keyword(s):  
Wind Tunnel ◽  
Static Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Circulation Control ◽  
Two Dimensional ◽  
Compressor Cascade ◽  
Flow Topology ◽  
Wind Tunnel Tests ◽  
Low Speed

Experimental and numerical results for the flow through a stator cascade with active flow control are discussed. By blowing air through a slot close to the trailing edge of the aerofoils, the deflection angle as well as the static pressure rise in the stator are increased. The aerofoil design is representative for a 1st-stage stator geometry of a multi-stage compressor adapted for low–speed applications. To allow a reasonable transfer of the high-speed results to low-speed wind tunnel conditions, a corresponding cascade geometry was generated applying the Prandtl–Glauert analogy. With this modified cascade numerical simulations and experiments have been conducted at a Reynolds number of 5 · 105. As a reference case two-dimensional flow simulations without circulation control are considered using a Navier–Stokes solver. In the related wind tunnel tests three–dimensional conditions occur in the test rig. Nevertheless five–hole probe measurements in the wake of the blade mid section show a good agreement with the theoretical characteristics. Additional investigation along the whole blade span gives a deeper insight into the flow topology. For design conditions different blowing rates are applied. The wind tunnel tests confirm the positive benefit, which is predicted by two-dimensional calculations. The offset between simulated and measured pressure rise decreases with increasing blowing mass flows due to the reduction of the axial velocity ratio. This result is related to a redistribution of the passage flow which can only be explained in a three–dimensional analysis including the side wall influence. The benefit of the circulation control at varying blowing rates is finally characterized by the efficiency and the static pressure rise per injected energy.

NASA Low-Speed Centrifugal Compressor for Three-Dimensional Viscous Code Assessment and Fundamental Flow Physics Research

1992 ◽  
Vol 114 (2) ◽  
pp. 295-303 ◽  
Author(s):  
M. D. Hathaway ◽  
J. R. Wood ◽  
C. A. Wasserbauer
Keyword(s):  
Centrifugal Compressor ◽  
Computational Fluid Dynamic ◽  
High Performance ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Field Measurements ◽  
Experimental Investigations ◽  
Nasa Lewis Research ◽  
Low Speed ◽  
Flow Physics

A low-speed centrifugal compressor facility recently built by the NASA Lewis Research Center is described. The purpose of this facility is to obtain detailed flow field measurements for computational fluid dynamic code assessment and flow physics modeling in support of Army and NASA efforts to advance small gas turbine engine technology. The facility is heavily instrumented with pressure and temperature probes, in both the stationary and rotating frames of reference, and has provisions for flow visualization and laser velocimetry. The facility will accommodate rotational speeds to 2400 rpm and is rated at pressures to 1.25 atm. The initial compressor stage being tested is geometrically and dynamically representative of modern high-performance centrifugal compressor stages with the exception of Mach number levels. Preliminary experimental investigations of inlet and exit flow uniformity and measurement repeatability are presented. These results demonstrate the high quality of the data that may be expected from this facility. The significance of synergism between computational fluid dynamic analyses and experimentation throughout the development of the low-speed centrifugal compressor facility is demonstrated.

Sign in / Sign up

Export Citation Format

Share Document