The demand of increasing pressure ratios for modern high compressors leads to decreasing blade heights in the last stages. As tip clearances (TC) cannot be reduced any amount and minimum values might necessary safety reasons, TC stages can reach notably higher than current norms. This intensified by a compressor running transient operations where thermal differences lead further growing clearances. For decades, detrimental effects large on an axial compressor's operating range efficiency are...

The authors report on using millimeter-wave images for real-time vehicle guidance. For application in the field of autonomous locomotion, main advantage this sensor concept is direct access to range and velocity information. System design imaging results a multitask 94-GHz pulse Doppler radar with 25-cm radial 1.5 degrees angular resolution are discussed. To point out specific scattering phenomena, various typically structured indoor situations presented. Extraction information from data,...

Since the early work on axial compressors, penalties due to radial clearances between blades and side walls are known an ongoing focus of research work. The periodic unsteadiness tip clearance vortex (TCV), its interaction with stator wakes, has only rarely been addressed in papers so far. current presents experimental numerical results from a four-stage low-speed compressor (LSRC) modeling state-of-the-art design. Time-resolved measurements have carried out at three different rotor (gap...

Proportionally large relative radial clearances can be found within the rear stages of multistage axial compressors gas turbines and aero engines, with significant impact on their efficiency. A new three-dimensional design for cantilevered stators in is presented, aim improving overall efficiency losses stage vanes hub clearances. The vane comprises an unconventional dihedral, special consideration to reduce caused by clearance vortex. was tested a 4-stage low speed research compressor under...

A major goal in axial compressor development is to increase the efficiency and reduce weight of module. In order do so power density has be increased by raising work per stage. Higher capability can achieved increasing circumferential velocity component fluid. Tandem stators might offer ability turn high swirling flow with lower losses compared a single blade stator. terms higher aerodynamic loading use tandem vanes key feature allow design highly efficient compact modules. This paper...

Abstract Linear cascades are commonly used as surrogate geometries when performing fundamental studies of turbomachinery blading. Several effects not accounted for in linear cascades, such the relative motion between blade and endwall. In this study, three different endwall velocities analyzed. The effect a compressor cascade is studied through direct numerical simulations. Results show significant change secondary flow structure within passage. Most notably, tip leakage vortex displaced...

The demand of increasing pressure ratios for modern high compressors leads to decreasing blade heights in the last stages. As tip clearances cannot be reduced any amount and minimum values might necessary safety reasons, clearance stages can reach notably higher than current norms. This intensified by a compressor running transient operations where thermal differences lead further growing clearances. For decades, detrimental effects large on an axial compressor’s operating range efficiency...

In high pressure compressors large tip clearances can occur in the rear stages especially during transient operation. This lead to a reduced operating range and performance of compressor. One simple means reduce negative effects rotor clearance increase be circumferential groove casing treatments. Their ability improve compressor is well-known for several decades. this paper, an experimental study investigate influence three different treatments on low speed axial research with very (5%...

Due to the high Reynolds numbers together with complex turbulent motions in turbomachinery, selecting a proper turbulence-modeling method is of vital significance interpreting real flow physics. In this paper, shear stress transport (SST) as Reynolds-averaged Navier–Stokes model and scale-adaptive simulation (SAS) zonal large eddy (ZLES) two scale-resolving approaches were chosen simulate low-speed axial compressor rotor at three different blade tip clearances (1.3, 2.6, 4.3% chord length)....

Abstract Rotating instability (RI) can be regarded as a pre-stall signal because such phenomena are usually detected when compressor operates at near-stall point. Since RI is closely relevant to aerodynamic, acoustic, and structural issues, its mechanism has attracted industrial concerns in-depth analysis. In this paper, low-speed axial single rotor row selected the baseline research object. A circumferential casing groove mounted over shroud. The solid treated configurations were simulated...

Abstract In axial compressors, an unsteady flow phenomenon associated with fluctuating tip leakage can be observed at stable operating points high aerodynamic loading close to stall, named rotating instability (RI). Within the frequency spectrum, e.g., from wall pressure measurements, RI is visualized as a hump lower than blade passing frequency. Since indicates increase in noise level and might cause vibration other undesirable structural issues, it has been hot-spot topic turbomachinery...

Abstract Film cooling and internal passage play a fundamental role in turbine blade cooling. As the holes are fed by crossflow, interaction of these both strategies is implicated. The influence film hole extraction on flow field heat transfer ribbed channel investigated this study. Therefore, rectangular (AR = 2:1) equipped with parallel ribs four different geometries (90 deg ribs, 60 V-shaped Λ-shaped ribs) also bleed at varying positions between ribs. geometrical configurations examined...

Experimental investigations in a single-stage low speed axial research compressor are presented. The influence of four different rotor tip clearances on the overall performance and flow field is investigated configurations with without circumferential groove casing treatments. Piezo-resistive pressure transducers used to capture unsteady region. effectively working at three largest clearance sizes. achieved operating range increase by 6.9%. can delay upstream movement interface between...

When a compressor is throttled to the near stall point, rotating instability (RI) often observed as significant increases of amplitude within narrow frequency band which can be regarded pre-stall disturbance. In current study, single rotor row with varying blade tip clearance (1.3%, 2.6% and 4.3% chord length) was numerically simulated using zonal large eddy simulation model. The mesh six passages selected capture proper dynamic feature after being validated in comparison measured data, mode...

This paper presents measurements conducted at a 4-stage low speed axial research compressor with cantilevered and shrouded stator vanes. The aim of the work is to compare these two design philosophies under rear stage conditions. To achieve blockage levels typical for stages, hub clearance first second vane row were kept constant 4% channel height. investigation done within third fourth compressor. Tests 4 different clearances over subsequently 3 mass flow rates through cavity stator....

The concurrent use of film cooling and internal plays an important role to maintain the life turbine blades increase thermal efficiency. Several studies were published on interaction these strategies but are mainly investigations how influences cooling. present study contributes improved understanding extraction through holes is influencing flow structures therefore field in channel investigated by measuring velocity distribution with 2D-PIV. Heat transfer measurements performed using...

Abstract For an axial compressor stator with tip gap, the boundary layer (BL) in hub endwall region has a significant influence on development and progression of leakage vortex. Herein, so-called BL skew, which develops through relative motion hub, is particular interest. Therefore, experimental numerical investigations single row varying gap height (tip height/chord length =2.0%|5.4%|6.7%) have been conducted. Comparing cases rotating or stationary segments upstream examined vanes allowed...

Since the early work on axial compressors penalties due to radial clearances between blades and side walls are known an ongoing focus of research work. The periodic unsteadiness tip clearance vortex, its interaction with stator wakes, has only rarely been addressed in papers so far. current presents experimental numerical results from a four stage low speed compressor modeling state art design. Time-resolved measurements have carried out at three different rotor (gap chord: 1.5%, 2.2%, 3.7%)...

With a vertical accuracy better than 1 m and collection rates up to 7000 km²/h, airborne interferometric synthetic aperture radars (InSAR) bridge the gap between space borne radar sensors optical LIDARs. This paper presents latest generation of X-band InSAR sensors, developed by Intermap Technologies^TM, which are operated on our four aircrafts. The collect data for NEXTMap^(R) program - digital elevation model (DEM) with contiguous U.S., Hawaii, most Western...

The ventilation flow of a gas turbine enclosure was investigated both experimentally and numerically in scaled test rig. Its components were inactive mainly functioned as obstructions. Measurements used to provide realistic boundary conditions verification data for URANS CFD investigations. In the rig active generator cooling created by several fans, modelled momentum sources CFD. Two different modelling approaches compared PIV data. found impact regions nearby but also far downstream with...

In recent years, steam turbines experience increasing quantities of load changes along with extended part operation, posing new challenges for the regulation turbines. Control valves are commonly used throttling turbines, accompanied by highly unsteady flow conditions at load. The resulting pressure fluctuations can trigger valve vibrations reduced component lifetime and structural failures. Most experimental research considers stiff configurations focus on improved shapes. As a result,...

A 35 GHz high resolution helicopter altimeter using the FMCW principle is described, which gives precise height information especially in region close to ground. The system uses full digital data processing including FM sweep linearisation and a near reflection cancellation. Inflight tests confirm ability of effectively support autorotation landings.

The paper presents results of an experimental investigation into the effects a periodic wake induced inlet disturbance on tip leakage flow in linear compressor cascade. A translatory generator, being equipped with circular cylinders, is used to produce unsteady inflow. setup resembles kinematic conditions found rotor region. variation coefficient ? considered account for arising from inappropriately oriented trajectories. evaluation cascade field mainly relies five-hole probe and...