A numerical method of solution of the inviscid, compressible, two-dimensional, unsteady flow on a blade-toblade stream surface through a stage (rotor and stator), or a single blade row, of an axial flow compressor or fan is described. A cyclic procedure has been developed for representation of adjacent blade-to-blade passages, which asymptotically achieves the correct phase between all passages of a stage. A shock-capturin g finitedifference method is employed in the interior of the passage, and a method-of-characteristiics technique is used at the boundaries. The blade slipstreams form two of the passage boundaries, and are treated as moving contact surfaces capable of supporting jumps in entropy and tangential velocity. The Kutta condition is imposed by requiring the slipstreams to originate at the trailing edges which are assumed to be sharp. Results are presented for a transonic fan stage. The rotor tip section solution is compared with an experimental pressure contour map. The subcritical stator solution is compared with results from a stream function method. Finally, the periodic solution for the stage, which has 44 rotor blades and 46 stator blades, is discussed.

Numerical Solution of Periodic Transonic Flow through a Fan Stage

An integrated nonlinear approach for turbomachinery forced response prediction. part i: formulation

The unsteady flow in stator-rotor interactions affects the structural integrity, aerodynamic performance of the stages, and blade-surface heat transfer Numerous viscous and inviscid computer programs are used for the prediction of unsteady flows in two-dimensional and three-dimensional stator-rotor interactions. The relative effects of the various components of flow unsteadiness on heat transfer are under investigation. In this paper it is shown that for subsonic cases, the reduced frequency parameter for boundary-layer calculations is about two orders of magnitude smaller than the reduced frequency parameter for the core flow. This means that for typical stator-rotor interactions, the unsteady flow terms are needed to resolve the location of disturbances in the core flow, but in many cases the instantaneous disturbances can be input in steady-flow boundary-layer computations to evaluate boundary-layer effects in a quasi-steady approximation. This hypothesis is tested by comparing computations with experimental data on a turbine rotor for which there are extensive experimental heat transfer data available in the open literature. An unsteady compressible inviscid two-dimensional computer program is used to predict the propagation of the upstream stator disturbances into the downstream rotor passages. The viscous wake (velocity defect) and potential flow (pressure fluctuation) perturbations from the upstream stator are modeled at the computational rotor-inlet boundary. The effects of these interactions on the unsteady rotor flow result in computed instantaneous velocity and pressure fields. The period of the rotor unsteadiness is one stator pitch. The instantaneous velocity fields on the rotor surfaces are input in a steady-flow differential boundary-layer program, which is used to compute the instantaneous heat transfer rate on the rotor blades. The results of these quasi-steady heat-transfer computations are compared with the results of unsteady heat transfer experiments and with the results of previous unsteady heat transfer computations. The unsteady flow fields explain the unsteady amplitudes and phases of the increases and decreases in instantaneous heat transfer rate. It is concluded that the present method is accurate for quantitative predictions of unsteady heat transfer in subsonic turbine flows.

Unsteady Flow/Quasi-Steady Heat Transfer Computations on a Turbine Rotor and Comparison With Experiments

Numerical investigations have been conducted on a transonic centrifugal compressor stage with a vaned diffuser. Due to the high loading and small radial gap between the impeller and diffuser, the unsteady impeller–diffuser interactions can be very large compared with axial compressors, and this has a significant impact on the time-averaged performance of a centrifugal compressor stage. Steady, unsteady and NonLinear Harmonic (NLH) simulations have been carried out to study the interactions in a transonic centrifugal compressor. Comparisons have been made against the overall performance and flow details. The distribution of deterministic correlations are extracted and compared to show the effect of unsteadiness due to impeller–diffuser interactions. All of these analyses show that the NLH method gains more accuracy compared with the steady-state mixing plane simulation and saves CPU time compared with an unsteady time-accurate computation. NLH and unsteady methods are in good agreement in overall performan...

Numerical investigations of impeller–diffuser interactions in a transonic centrifugal compressor stage using nonlinear harmonic method

The average-passage equation system (APES) provides a rigorous framework to account for the deterministic unsteady effects by the so-called deterministic correlations (DC), which include both deterministic stress correlations (DCS) and deterministic total enthalpy correlations (DCH). These correlations should be modeled to close the system of equations. In this paper, the distribution of DC in a transonic centrifugal compressor is presented, and its relative importance is revealed. The assumption made by Adamczyk that the pure unsteady fluctuation is significantly smaller than the spatial fluctuation is verified at the impeller-diffuser interface. The decomposition of DCH is also discussed to determine its two different physical mechanisms. Finally, the transport equations in terms of DCS in cylindrical coordinates are derived, and the terms are evaluated to determine the ones that are necessary to model. All these analyses significantly contribute to our model development for DC in centrifugal compressors.

Investigation of model development for deterministic correlations associated with impeller-diffuser interactions in centrifugal compressors

A numerical method of solution of the inviscid, compressible, two-dimensional unsteady flow on a blade-to-blade stream surface through a stage (rotor and stator) or a single blade row of an axial flow compressor or fan is described. A cyclic procedure has been developed for representation of adjacent blade-to-blade passages which asymptotically achieves the correct phase between all passages of a stage. A shock-capturing finite difference method is employed in the interior of the passage, and a method of characteristics technique is used at the boundaries. The blade slipstreams form two of the passage boundaries and are treated as moving contact surfaces capable of supporting jumps in entropy and tangential velocity. The Kutta condition is imposed by requiring the slipstreams to originate at the trailing edges, which are assumed to be sharp. Results are presented for several transonic fan rotors and compared with available experimental data, consisting of holographic observations of shock structure and pressure contour maps. A subcritical stator solution is also compared with results from a relaxation method. Finally, a periodic solution for a stage consisting of 44 rotor blades and 46 stator blades is discussed.

https://ntrs.nasa.gov/api/citations/19780012139/downloads/19780012139.pdf

Computation of unsteady transonic flows through rotating and stationary cascades. 1: Method of analysis

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

E. Alzner

Author Tools

Chat about Author

Papers

Computation of unsteady transonic flows through rotating and stationary cascades. 1: Method of analysis